Expert Techniques in Advanced Vehicle Diagnostics: A Comprehensive Workshop

hi I'm John foro from a today I want to talk to you about a diagnostic class I know as of late you've seen me doing a lot of EV classes hence the whole social media name of electron John but you know I got my roots in this industry doing engine drivability type of classes so today's subject matter is going to be on drivability there's a lot of stuff that I see on different social media pages and different forums that I'm a part of where people are maybe maybe having a little bit of misconception on how to diagnose some different types of problems so what I want to do is I want to kind of keep this kind of generic but I call this Advanced system testings you'll see that there's many roads that will leave you to the same destination just like in life you know there's many different paths we can get from point A to point B many different routes we can take so to speak so there's really no wrong way of doing this as long as we originally or eventually arrive at our destination but our goal here today is to try to get inside the mindset of a diagnostician so you know a lot of times people will ask me hey what's your favorite goto tool or whatever case happens to be and I always tell people that most of my diagnostic processes involve two primary tools one is going to be a scan tool obviously a scan tool without a doubt that's going to be my starting point with just about any kind of Diagnostics unless it's you know a headlights not turning on or something like that and then eventually I'm probably going to break out a scope for a lot of the different drivability type of problems and I'm not telling you that that's what you have to do I'm just giving you an insight as to how my mind works when I'm faced with the driveability type of problem I try to get as much information as I can from my scan tool before I ever open the hood on a car and if the vehicle comes in and I'm just going to throw an an example out there that says the vehicle's running rough whether or not there's a trouble code associated with it doesn't doesn't bother me at all I'm going to go through the scan tool screen and in that one example that I gave you there's a your your problem's going to turn out to be either something with the ignition system the fuel system or an engine mechanical problem if it's running rough whether there's a misfire whatever so we were all we're all professional technicians and we all know hey I could start off by doing a doing a actual compression test doing a cylinder leakage test vacuum gauge test hooking up a a scope to the ignition system I could do all these tests but we want to do it more logically and we don't want to take a holistic approach and test all these different systems we want to get to the system that's causing the fault so I'll start with the scan tool I key in on six main lines of data so six different pits those six pits a lot of times I'm going to generic or Global OBD2 for these for the main simple purpose that I don't have interpreted data that if there's a hard fault that we're having a substituted data from different car lines or anything like that these six lines of data are always found on every type of car on the global side of OBD2 those six lines of data that I'm concentrating on are the temperature inputs the O2 sensors both pre and postcat my load sensor so whether map mass airf flow whatever my demand sensor which is throttle position and my RPM sensors and fuel trims both shortterm and longterm now if I zero in on looking at those six main lines of data and as we go through this little presentation here before we start turning it over live to this vehicle you'll kind of understand what my thought process is and what I use those six lines of data for now I'm not saying that if if I have a specific diagnostic trouble code so if I had a specific diagnostic trouble code say for an EVAP system related problem well I might look at some of those lines of data but by the same token if I have a code I'm probably going to be using a different whole diagnostic process because I the computer has generated a code for me I'm talking about if it's a a misfire code or if it's just a driveability complaint type of scenario that I'm trying to use these six lines of data here so let's take a look at what I use some of these some of these different pids for so my temperature PID I'll use that for Rich running type of scenarios so maybe the complaint comes in and it smells like rotten eggs or something because it's running rich or maybe the fuel trim is is telling me that it's trying trying to take away fuel for whatever reason I'm also looking at my temperature pit for restricted exhaust so an engine breathing type of ability so if I'm looking at my intake air temperature sensor for instance and I'm comparing that to similar type of inputs so like coolant temperature maybe barometric pressure stuff along those lines and I see that my my intake air temperature sensor no matter where it's located whether it's in an intake man manold inside of an air cleaner housing I don't care where the manufacturer put it if I start to see that getting too high right so if I'm looking at my scan tool and it's it's got lack of power type of complaint or maybe it's running rough or whatever the scenario happens to be and I look at my intake air temperature and I see that that's 180° we'll just throw that figure out there well if I'm still alive and I'm still actually able to comprehend what I'm doing on my scan tool it can't be 180° I get it there's underhood temperatures and maybe if you're in the desert and stuff you know but realistically that's an extremely high intake air temperature reading you know and if it's higher then obviously everything follows suit with this so where's it getting that extra temperature from it's getting it because that hot exhaust gases which could be you know 6 700 degrees of Fahrenheit can't make its way out the tailpipe so it's finding its next hole in this case happens to be the throttle plates which is how we're actually increasing that intake air temperature sensor value I'm also looking at my rpm sensor right my rpm sensor that's telling me conditions for you know crank signals here's a prime example of this let's say it's a no start and the car cranks over fine well we all know that we need an RPM signal we need an RPM signal so that the fuel injectors can start spraying fuel the spark plugs could start firing and everything else if the car and most of them do if the car manufacturer supports just a cranking RPM on your scan tool you can actually kind of rule out if you're if the computer is seeing that input if it's saying that it's got zero RPM and the Carline supports the cranking RPM like again again most car manufacturers do well then that's going to be one of the first things I want to turn my attention to now before we get too much further ahead I always want to back up a suspicion right so we'll use the first one the temperature as an example if I thought looking at that scan tool with the intake air temperature sensor if I thought I had a restricted exhaust because that temperature was too high I'm not going to stop there I'm going to look at other pids to help me verify that that is in fact what is the problem because what I'm basically trying to accomplish here is when I get my butt out of the driver's seat and I decide to start doing pinpoint testing on the system system I want to I want to verify and I want to justify any type of time it's going to take me to do a series of tests now those series of tests in my head I've got if it was a breathing type of scenario maybe I want to do a compression test a cylinder leakage test whatever the case happens to be I'm going to come around I'm going to open up the hood now my diagnostic path may change depending on how hard it is to do some of these tests so maybe one of the tests I wanted to do for that scenario would have been an in cylinder pressure transducer test right' be a great test to do but if I open the hood and I determine that hey half the cylinders are covered by the intake manifold or possibly maybe it's a Triton Ford and I didn't want to risk the spark plugs breaking off as I try to unscrew them or whatever I may I still want those test results but I may come up with another way of doing it that's easier for that particular application so let's continue on looking at some some of those other pids so I'm looking at my O2 sensors pre and postcat now if it has an air fuel ratio sensor as of late and every all the late model cars again this is one of the benefits of going into Global OBD2 because I can still look at O2 sensors the way that I was accustomed to seeing it on the data stream pits so what am I using my O2 sensors for I'm using those to help me diagnose a misfire problem a fuel issue problem vacuum leaks or exhaust leak problems um basically a rule of thumb and we'll come back to this here in a little bit but a rule of thumb if I look at my postcat O2 sensors and they're higher or greater than 600 molts with the Upstream being lower or normal that's usually an indication it's running rough that's an indication that it's an ignition type of problem right now I'm going to look at some of the other pids to verify that but it's an indication that the reason why this car is running and rough is because it's ignition related if it's lower than 200 molts then it's usually an indication that it's a fuel related problem and that opens up a whole different series of tests that I'm going to do my ratio sensors if I was on the OEM side of the data stream I'd be looking at my pumping current right so you know if it's up if the pumping current value is is higher that's usually indicating lean if it's lower that's usually indicating rich and Lambda a lot of the different car manufacturers support Lambda now especially on global OBD2 side Lambda less than one is indicating a rich condition so obviously higher than one is going to indicate the opposite my throttle position sensor well this goes along with the actual strategies that the computers have in it so one of those strategies could be clear flood mode and in clear flood mode a lot of cars support that if it sees that the cranking RPM is low but but the actual throttle position sensor or pedal position sensor if it's a newer type of car is actually saying that it's at you know wide open throttle or pretty close to it well now the computer is going to think that you're in clear flood mode and it's not going to turn the fuel injectors on so the car won't want to start right so does it match the load that's another thing I look at the TPS for if I if I have a mass air flow or if I have a map sensor whatever the car manufacturer has in theory if I stepped on the gas pedal there should be no lag time for all of a sudden those throttle plates open up for that incoming air past let's use a mass air flow as an example to actually pick up that increase of air flow if there is a lack of time that occurs usually it's going to be like a hesitation type of complaint stumbling lack of power type of complaint something like that well that's a pretty good indication that there's a problem with the mass air flow possibly something as simple as just a contaminated hot wire on the mass airflow sensor and then obviously I'm going to be looking at that sensor for any type of possible glitches as well again I'm always going to be backing It Up by looking at other lines of data so then I also have two more pids that we talked about it's my six goto pits right if you watched any of my drive abil any my electric vehicle classes you know that in those types of vehicles I have 20 go-to pits but in drivability related stuff way easier got only six so I'm also looking at fuel trims in my load sensor so again my load sensor whether it's mass airflow or map doesn't much matter some of the indications that I get off of that is is there any type of pirate error getting inside the engine is there a vacuum leak that's causing this to to have to run rich or run lean whatever the case happens to be are they possibly um contaminated hot wires associated with it the calibration of the mass airflow sensor itself right so we'll call again we're going to go into greater detail with some of this stuff as we go on here right now I just want to focus on my six Main pids and what how my mind interprets these pits so my fuel trims short and long term that's obviously telling me a good insight as to whether the system's running rich or lean um fuel system issues it's going if it's a fuel system related issue with the fuel trim that should go ahead and affect the entire dynamic range of op operation right so let's say if I have a weak fuel pump or a restricted fuel filter you we we'll keep it as simple as possible for this quick explanation it's not just going to be weak or restricted at idle or off idle it's going to have a lack of fuel pressure the entire dynamic range so this is how I can start using some of this stuff so that when I get out of the driver's seat and start doing pinpoint testing I know the series of tests that I want to do again it may change on once I open the hood and see how hard it is to do but as you go through and you kind of see the the the slide that we were talking about there you know if it's ignition system related problems as opposed to fuel system related problems that is going to affect fuel trims as well but they going to be minor type of Corrections you're not going to have a a positive 25 or a POS if you're on the generic side positive 98% if it's ignition related that's going to be more of a fuel related type of thing so this is going to be the six main pids that I focus the majority of my attention on and if I if we understand this right so if I looked at the scan tool while I'm sitting in the driver's seat and we use that complaint of hey it's running rough you know whether or not there's a P0300 code associated with it it's either going to be fuel or it's going to be engine engine breathing capabilities we'll call it or it's going to be ignition so which one which series of tests do I want to pull from my diagnostic Arsenal to get to the root problem here right and then I want to do them as quickly and efficiently as possible that gives me the same type of test results here so now when I open the hood on the car it's not like I'm wearing a blindfold and have no diagnostic direction to go into so what do I really need to diagnose anything and I've said this for many many years you know I'm old as dirt I've been doing this for over 30 years doing training classes you need a system or a circuit knowledge of how something's supposed to work if you don't have that you are handcuffing your diagnostic success the outcome of the S the success of the outcome that you're trying to accomplish here so if you have to if it's a car line that maybe you're not familiar with or something it would behoove you to maybe do a little bit of research on your information system maybe you need a wiring schematic whatever the case happens to be and then also you need to understand PCM strategies whether it's regarding mode six or just overall strategy so what's a strategy we'll keep it real simple for this quick introduction part here we all know of a strategy called open or closed loop right so in open loop it's when The Cars first started that oxygen sensor has to heat up to about 600 Degrees fhe before it's ever going to go into closed loop right so in open loop let's say we're going to be looking at Key inputs so those key inputs are going to be temperature sensor throttle position load sensor you know we're going to be looking at Key inputs we're not looking at an O2 sensor input because we're not even using the O2 sensors during open loop operation so the reason why I chose that one as an example here is let's say you get a customer that brings you a car and they tell you it has a drivability issue only when it's first started and you scan it for codes if that was your standard you know mode of operation there you scan it for code and you see you got an O2 sensor code stored well that may be a problem and you might be able to fix that but if all you did was fix that O2 sensor code that driveability complaint is still going to be present because again the computer wasn't looking at that for that drivability condition so again your information system is loaded with all kinds of different system strategies and stuff mode 6 there's a ton of training classes that I've done over the years there's a lot of information out there I I share with a lot of the different um posts and stuff that I do I share some of these strategies with you so you know regarding mode 6 we'll use this as a quick example this is something I did years ago this is when Ford did not you needed a secret decoder ring right so they would give you hexit Smo code and then forward tell you to use some crazy decimal point thing and it you know multiply it by each other to get a value that actually made sense to us but it doesn't matter even if it did actually tell you if we fast forward to a more modern day car it would still give you the same type of information so this one here is a Ford example and it's about an EVAP system right so it tells me that for this particular heximal code which was test identification dollar sign 2C it's testing for a 20,000 Sleek so 2,000 model years and later and there is a phase two tests that it failed it for right so I'll just fast forward there's four phases on those cars right so phase two is what failed on that EVAP system test and it was an idle check and it told me how the computer was trying to test it and it was outside of that range which is why it set that code right so again if I go to another slide here and and kept talking about it I kind of would walk you through the most logical types of tests here but if I had a generic code for instance say a p0440 for an EVAP related code mode 6 could be very beneficial because if I saw that that code that the phase of the testing strategy that it actually failed so if I thought it was a 440 we'll just use you know backyard mechanic mentality right here and people say well let's put a gas cap on it right well is it going to fix it right now you you would know that if you understood how to interpret the mode 6 data because if it was a gross leak that was failing the large leak test the small leak test and the different phases that Ford had there then you could you could justify the fact of hey it could be that the gas Cap's missing or the gas Cap's bad or whatever but if it was a small leak test and you saw that it was done under certain drivability conditions then that would rule out the Poss possibility of a bad gas cap so this is how our mindset has to think and as we go through some of how we approach some of these different types of problems it may help to see maybe a possible case study before we actually turn it loose on the actual card over here so I'm going to do one quick case study this is on a lack of communication type of problem right so if it's whether it's can L I don't care what the network happens to be we'll use can as an example you know on your screen you see that there's a good can high and can low signal being displayed right there so in theory your scope if you have one you could use a breakout box go to terminal 6 and 14 you can pull the two signals over to one another you're seeing the messages going between the different computers shared along the data bus communication lines right so we'll use as an example this is an 06 Buick LaCrosse cxl it was a no start no communication type of complaint that came into my shop one time and again it's not necessarily that the case study is what we're trying to teach you it's it's the thought process that I have so that you can use this thought process when you're faced with whatever the type of case study happens to be that you're confronted with so the customer called me up and they said hey I just bought this car um I there there's no warranty on the car I already tried going back to the dealership I took it to my other mechanic my other mechanic you know replaced the battery because even though it cranked um it wouldn't start at times but even though it would crank when it wouldn't start you know he said that I should probably start with the battery anyways which doesn't make any sense to me but whatever and you know it's intermittent sometimes it'll start up no problem other times it won't it seems like when it doesn't start though it makes this loud pitch howling noise sometimes and I'm like yeah you just bring me the car right so the car comes to me I you know luckily the problem was there it showed up and everything but even if it wasn't there I could go through and I could take a can signal waveform from my scan tool and I could probably have seen the problem even if it wasn't showing up at the time not saying that's always going to be the case but for this particular one it probably would have showed up so you know I went ahead I verified it wouldn't crank no lights are coming on on the dash nothing right which maybe that's why the other mechanics said wanted to put a battery in I'm not sure what his thought process was with that so and I did hear a noise and that noise was coming from the rear speakers on the vehicle it wasn't constant you know it pretty much happened every time I'd have it into the cranking mode so if it had a key if you hold the key over to crank mode that's when you'd hear that noise if you release the key it would go away which was weird right but you know I just used all my senses all my human senses and I just put that in the back for future reference right so I wanted to go ahead cuz I had no communication with my scan tool and that's one of my go-to tools as we said earlier so since I had no communication that made me say okay well let me check the datab bus networks I hooked up my OBD2 breakout box and I tried to get a waveform now this particular vehicle was used in j1850 right which is another form of communication for those of you that are in the know with this stuff but the signal should be with the key in the on position as long as the network is awake should be between Z and 7 volts and right away I noticed that on the j1850 line that was the waveform I was seeing so you know I didn't spend a whole lot of time setting up the scope I could have stretched that out and saw the information packets a little bit wider and everything if I had checked my time base I was just looking for a good go or no go type of signal and this was definitely a no-go type of signal because those it never went low right that whole communication line was staying higher than the Zer volt threshold there so I knew I had a problem now what the problem was I don't know and this is something that always bothered me about you know any type of communication type of fault was you know eventually if you followed a flowchart or something it may tell you to start unplugging modules one one by one which would be okay if all the modules were easy to get to but you guys know these modules are HID all throughout the you got to take all kinds of stuff apart on the car to get to them so this particular system here used a shorting bar so the shorting bar was located used a couple shorting bars actually on this one but the one that was being that had the effect going with it was located underneath the steering column area on the vehicle so I pulled the shorting bar down and I said okay so I got to remove the comb right so going to remove the comb that's part that actually shorts that splice connector out there and I print it out a schematic again I don't know how that system is wired so I have to go to my information system and print out a schematic and I see that there's a series of different modules on that particular splice that shorting splice there and I see that one of the one of the lines of data going to that splice is actually shared by both the radio and an airbag system now in my mind right I'm thinking in my head I should start with that side of the shorting splice right because the radio is making a noise and plus if you know anything about these cars you know that the airbag is located underneath the passenger seat a lot of times carpet gets all saturated with water and then it wants to corrode right but I said no I'm just going to start logically with the numbers so I started at the other end and what I did is when I removed that shorting bar it took all of those modules off the network I still had my lab scope and everything hooked up and I used a set of jumper wires and I put one module back on the network at a time and I was monitoring for a good communication signal now if I saw it going from you know the S volts down to Z volts I knew that that module that circuit I should say was not the problem so as I did that going all the way up that ladder in that shorting bar when I got to the last one the one that shared the two my initial gut reaction was I should have started from that end but I wanted to verify them all that's when I got the bad signal again so I knew that it had something to do with one of those two modules or circuits so just like anything you want to check powers and grounds and all that stuff but I figured in my head well let me just go ahead and disconnect one of those two modules so this is where my my first fork in the road came do I want to take the dash apart to get to the radio so I can unplug the radio or or do I want to take basically the passenger seat out pull the carpeting back and do the airbag module and in my head it was it was a real controversy because I was having that stereo noise right so I almost took the dash apart but I said you know from experience let me go after the passenger seat so I took the passenger seat out and I noticed as soon as I was working on my hands and knees getting to the bolts and everything that carpet is extremely wet which made me feel more confident at the time right so carpet was extremely wet and as I peel the carpet back the way how the floorboards made and everything there is like an inch and a half 2 Ines of standing water on the floorboard so now I'm thinking hey maybe this vehicle's been in a flood whatever I get to the actual airbag module and this is what I found right so there's the picture of the original airbag module and the one that I replaced it with is obviously higher up and then the picture on the right is the actual faulty airbag module so as soon as I saw that I'm like oh this is definitely going to be it but I unplugged it anyways and then everything was normal again so at this point you know you call the customer you get the okay to do the job accordingly so after it was all said and done put the car back together that's what that pattern was supposed to look like right but this was my mindset as to how to diagnose this it all started with the customer call and obviously verified the complaint I hooked up a scan tool that's always one of my first steps when I had no communication then I went to my scope and then once I got my scope involved I started to see the diagnostic process unfold in front of me here so at this point what I want to do is I want to I want to kind of talk about what can I do with not necessarily looking at the data stream on the car because those quick little silver bullets I gave you about hey you know if it happens to be a a misfire problem and you're looking at your postcat O2 sensor what the value should be and stuff I think you kind of have that I want to visit the scope right so with the scope if it's got an engine breathing type of problem well what could cause that right so I could open the hood if I determined I had a a mechanical problem I could open the hood on the car and like we said before start off by doing a manual compression test then going to a cylinder leakage test the benefit to using an in cylinder pressure transducer is technically I do both of those tests electronically at the same time be by going directly inside the cylinder I can see the valve train operation plus I can see the overall compression so that's that's a shortcut that I could choose to do if I wanted to I could do those old-fashioned mechanical type of test maybe I open the hood on the car and I say hey I want to do a compression test but half the cylinders are covered by an intake manifold but I still want to know if I got good compression well maybe I do a relative compression test right as opposed to a mechanical compression test so I have a lot of options available to me I want to talk about the test results and what I use some of these for because if I I'm just going to throw some different diagnostic scenarios out there and show you some of the advanced testing procedures you can do with your scope so I've got up on the table in front of me here a series of different types of tooling and stuff and you know here's a pressure transducer so I've got the I've got the Pico one right here that's made to go inside a cylinder and then it can also go to a vacuum hose or whatever else I want and then I got the less expensive style and this one here I cannot put it inside a of a combustion chamber because the pressure would be too high so this one has like a little vacuum diaphrag fragm inside of it and if I obviously try to put 150 psi of pressure through there I'm going to rupture that diaphragm so but this sensor is a pretty Universal type of sensor I can put this in and measure lower types of pressure or Vacuum readings like in the exhaust tail pipe possibly into a vacuum hose if there's Blow by in the engine which I'm going to explain all this stuff to you guys I can get a lot of diagnostic test results with this style pressure transducer which is a fraction of the cost of the big dollar Pico one right the Pico one is by far you know one of my favorite ones it's a go-to it can do anything that I want it to do however if you're on a budget it's not a bad idea to pick yourself up one of these you could do all the same test that I'm about to show you with the exception of putting it inside the combustion chamber for that I would would need the more expensive Pico version also I have a couple little leads here so these leads are very inexpensive I got them right from AES wave these leads are invaluable so basically I've got a red one and a green one the difference between them is the red one is for Ultrasonic testing the green one is for frequency so if I had let's say a no type of complaint well with a modern-day vehicle right it's probably got a push button start on there I have to have the right I have to have the key fob inside the car also it's probably got a little push button on the door handle that's supposed to unlock the doors as I walk up to it all that kind of stuff anything that measures frequency on the car I now can take my frequency style connector hook it up to my scope and I can get a lot of diagnostic test results so for example if I had a a no start on a modern-day car I could have a bad battery I could have a bad starter I could have all the normal stuff I could also have a bad sensor that's picking up anything from the key fob to the actual push button on the dash how would I normally test that if I didn't have that I'd probably scan it for codes maybe use topology screen scan it for codes and if I was lucky I had a code to go on right but still eventually you get to a point where hey does the transponder actually work in that push button on the push button start system well here's a great tool for being able to figure that out I can have my foot on the brake in park and everything and just push that button hold this hold the little sensor in close proximity to it and I should get away for them on the screen the ultrasonic one that's great for any type of backup alerts right I'm not talking backup cameras I'm talking about the little alerts that are that are beeping as you get closer to a brick wall as you're backing up or something like that or anything that emits an ultrasonic type of signal on a vehicle and each one of these leads are roughly about the $30 range and like I said these are both made by Pico but I got them from you know a Suave out of California George and Carlos then this particular sensor that we talked about earlier I got this from Jarhead Diagnostics right so they got a website you can go there they got a whole whole host of different types of you know sensors 3D printed type of stuff so this is a 3D printed case around my Pico transducer just to help absorb any kind of impact if it was to fall or something so that's just some extra protection there but you know none of the stuff is extremely expensive and then I also have for doing some other types of testing here a few more different types of leads here and this I got from a guy by the name of joke Casey now I apologize I don't know Joe Casey's website I think it's something like Joe's Auto electric.com but I could be wrong with that just Google search his name but this is another very talented individual that I'm friends with within the industry he's got a pressure transducer that you can use to hook right on to vacuum hoses and stuff he's also got a frequency style tensor uh sensor here that's made for picking up noises so picture this the customer comes in and they're complaining about you know hey it's got a rotational noise and it's a wheel bearing thing and you know the the one the types of noises that create a lot of bass it's always hard for the human ear to differentiate exactly which one it is it could be a noock sensor that you're trying to diagnose it could be a wheel bearing it could be any type of noise these are really nice very affordable very high quality stuff and then he's also got a little tool here another little adapter that's made to test ignition systems or basically things with magnetic fields that are collapsing right so most of the time you're going to be using it to test ignition coils and stuff so I'm going to be using some of these things just as quick go-to test as we go through there so paying uh focusing our attention back on the on the PowerPoint before we get started on the car some of the stuff I'm going to be looking for I get a scenario the customer says it's running rough whether or not there's a misfire code I don't care I could quickly verify if it is at actually running rough because if it is running rough it's going to affect the exhaust pulses coming out of the tailpipe right now if it's a dead misfire it's going to extremely affect them so this is something I did real quick I just walked to the back of the car and I'm going to do it on on camera here in a little bit I put a pressure transducer in the tailpipe I get a good go or no-o style test what I'm looking for is uniformity on these initial tests when I'm using a pressure transducer if I wanted to deter determine whether or not I had excessive Blow by in the engine blowby could be bad Rings or whatever the case happens to be again I'm looking for a uniformity so there's a picture of a good engine on the right comparing it to a bad engine now again this is a good go or no-go type of test I'm going to on this particular car I just got to get hooked up to the crank case somehow so they sell adapters you can take the oil fill cap off and stuff I just use the dipstick tube right 99% of the cars still have a dipstick on it so I just pull a dipstick tube out put the pressure transducer inside the dipstick tube to get this type of result and the reason why these are go or no-o style tests is because if I got the waveform that's on the left that says excessive blowby we know that there's a problem because it's not uniform there but I don't know which cylinder that is right so if I wanted to determine the cylinder that's causing the problem I'd have to hook up a second channel of my scope and I'd have to hook hook it up to something that's going to display firing order so either the ignition system or the fuel system a fuel injector or an actual you know spark plug or coil pack or something and then as I go through here with the exhaust pulses again here's a picture of a faulty coil that's causing a problem in those exhaust pulses right and I can do the same thing by hooking up to a vacuum hose and a vacuum hose is going to in essence give me a cylinder leakage type of test result because I'm seeing the opening and closing of those intake and exhaust valves again the first test is just hook the pressure transducer up one channel quick go or noo if it's if I'm getting uniform results across the screen I'm good I'm going on to the next test if I get something that looks suspicious those scenarios I'm going to take some time and actually hook up a second channel to say an ignition coil pack or or whatever the case happens to be so I've got some firing order frame of reference so when I start going through this I'm going to kind of do it quickly on this car when I start going through this on the car I'm going to be using pressure transducers I'm going to be using you know the ignition system adapters I actually going to be using the one from from uh Joe's Auto Electric here placed right on there right off cylinder number one but I'm also going to be using an inductive current probe right and I'm going to clamp this around the ignition system as well so again it's not going to take a whole lot of time to get these test results I can do the same thing for relative compression if this is something that you guys kind of like I want to keep this video as short as possible but if you guys want more information like this you can always put in the comments of hey we'd like to see some more advanced system testing um strategies and we can do a whole series of different types of tests so what I'm going to do I'm going to just go ahead and I'm going to have my scan tool powered up right now I'm going to turn the scope on AEL calls it calls it the measurement screen I'm going to turn the scope on my one channel I already have the pressure transducer in the exhaust pipe of this car so once I start the car up I'm going to get a pattern I purposely chose a car that doesn't have a problem because I want to show you what the good patterns look like so you got something to compare for a point of reference to so the guys that have seen me do a lot of drivability classes in the past know that a lot of times I I'll use a Pico scope maybe I'll use the ATS scope whatever the case happens to be so I wanted to choose a different type of scope for this particular video so I chose the autel scope plus it doesn't hurt the fact that you know AEL gives me a paycheck every week as well so I figure i' give them some publicity here now channel a is the default if I hit the little button at the bottom that says Auto DC for next to the a I can go in and I can actually set up my voltage scale right here it's going to default to Auto just like most scopes on the market does I usually just leave it on auto till I acquire the signal then I'll come back in here and change it so that I get what I want to see on the screen if I went down one for probe setting here the accessory kit that comes as an option with autel if I wanted to use an actual current probe or something you'll see me do this as we go through these tests I'm going to scroll through here and tell it that I'm going to use a current probe right and then if I had a a component so altel does not make a pressure transducer but if I wanted to use a pressure transducer for you know future reference in the future I can always create a custom lead and I would do that by the probe edit button down here one last thing is if it ends up being a dirty signal so it's got a lot of noise in the signal autel has the low pass filtering where I can turn on and adjust the filter amount per Channel I don't think we're going to need to use the low pass filtering on what I'm about to do but I'm just going to kind of show you how I how I do this so what I'm going to do is I'm going to start the car up I'm going to just have Channel a on we're going to get a waveform I'm going to make a couple little small adjustments on the screen as we go then I'm going to go ahead and turn on channel B which I already have again this is going to be Joe Casey's um ignition input here we're going to get we're going to we're going to get a number one trigger adjustment here so if there was a problem on a cylinder I now have a firing order displayed so we're going to make a couple adjustments on the screen once we turn Channel B on again and then finally we'll turn Channel C on which is a low amp current probe which is going to the coil primary circuit cry here for all four cylinders this is a four-cylinder vehicle so I could select the driver for just cylinder number one if I wanted to but I wanted to get all four patterns on there so that's the progression we're going to make after I do that then I don't really care about the other two channels anymore I'll probably turn those back off and I'll just show you since we talked about it I'll show you going to say the crank case right and I'll pull the dipstick tube out we'll go in there you'll kind of see the same um same examples of what we're talking about here so I'm going to go inside the car real quick I'm just going to start the car up as you can see in Auto preset it's trying to display a pattern for me now I want to get all four cylinders on the screen at once so to do that I can go and adjust the time base let's try 20 milliseconds and see what we got here I'm going to let the RPM come down this this is a cold start here and I'm going to go back into the actual voltage scale here and I'm going to just select let's go ahead and select 200 molts I'm just using the force here it's not quite enough let's go with two volts per division all right so now I could adjust the time base so that I see but you can kind of see each one of those up and down spikes there camel humps whatever you want to refer to as is one of the cylinders now this is a four cylinder if I would if I had a problem one of those would not look like the others right I wouldn't know which cylinder was causing the problem because i' need to turn on a second Channel now normally for training purposes I would adjust the time base a little bit to just get four of these on the screen but since I'm about to turn on a couple more channels I'm going to leave it at this time base for the time being and not make the final adjustment till I got all three channels up and running so the second Channel I'm going to turn on is channel B and I am going to say that hey let's go ahead and go with a a 5V pattern and you notice here I've got a green Channel being displayed now and it's upside down so this is the one that's again going showing me a secondary ignition pattern so let's go back into Channel B there and let's go to the probe setting and we're going to hit the invert button try to hit the invert button at least okay so now that I got the invert button on now I've got it so it's flipped now I could have did the same thing by taking the actual component and just flipping it around but it's easy I'm already at the scope so now technically I know where number one is is on the screen now I should change a voltage scale because you see it says over range so I'll do that just to be technically correct let's see what if 10 volts would be enough so 10 volts seems like it's enough but again all of this right now is just I still don't have channel 3 hooked up so I might have to change these scales a little bit more to get a better picture so I'm going to go ahead and plug in channel 3 to the vehicle and again this channel is actually going to be my current probe so I'm going to turn on channel C I'm going to go to probe setting I'm going to select the current probe that I'm using I'm just going to say yeah okay I don't care about that all right so now I got three channels now here's the problem they're all right on top of each other so like with most Scopes I can actually grab one of these channels and kind of move it where I want it to go so that it's a little bit easier for us to have def definition of these different patterns now when I do that it's not actually changing the time the voltage scale or time base or anything so it's not going to say that it's out of range you're just not going to see the top part of the pattern on some of these or the lower part of the pattern depending on where I grab these patterns to to move them on the screen so I can move it you know to the bottom part of the screen I can move it to the top part of the screen but this is how I could get the different types of patterns on there and again I would never go this far normally unless I saw that my red pattern I'm just going to turn these other two channels off again so it's a little bit easier if that red pattern was not uniform which this one is then I would go through those extra steps and I wouldn't necessarily put on both channels I'd probably only put on one because all I really need is one type of firing order input and then I can use this to help me diagnose the car cuz remember if it's running rough or it's misfiring it's affecting the exhaust pressure that pulse of air coming out of the exhaust pipe so now what I'm going to do is I'm just going to do the same type of test I'm just going to show you another example that we had in the PowerPoint I'm just going to I'm not going to go through them all just going to go to the crank case right so I'm going to take the exhaust um the pressure transducer out of the tail pipe of this car and I'm going to get some vacuum hose adapters so that when I go over to the actual crank case here I'm going to pull the dipstick tube out not sure if you pick that up on the audio or not but because it's mass airf flow once I pulled that dipstick tube out the engine started to run a little bit rough and here I'm displaying a crank case pressure transducer waveform and again I'd be looking for something that was not uniform and I'd take the same series of steps so if something was out of whack here again I wouldn't necessarily know which cylinder was what so I'd have to turn on channel 2 and get some type of pressure or some type of RPM type of input here for the firing order so I know which cylinders could possibly be causing the problem now one little word of advice when we're dealing with exhaust back pressure it's a it's a tube right it's a it's an exhaust pipe so when I look at my actual waveform coming in the exhaust and I hook up to a firing order here it takes a little bit of time for that pulse of that exhaust pulse to make its way from the engine out to the tailpipe so again in the PowerPoint that you guys that we shared we talked about on one of the slides if it's a four-cylinder six-cylinder 8 cylinder let's say I triggered off number one as my firing input I have to count a couple exhaust pulses after that because it took that time to go out the tailpipe just wanted to make reference to that so if you guys want to see more information like this I'll be more than happy to make as many of these types of videos as as you guys deem um worthy to actually do it but I wanted to show you some of the advanced system testing how more importantly how my mindset works of using those six main inputs to get a diagnostic pathway we all know the types of tests we're supposed to do to help determine if it's ignition fuel whatever but then using maybe some more advanced testing procedures to get the same test results you want in a shorter amount of time so hopefully you guys found this useful and I look forward to seeing you guys again in a future training video thanks

Channel: Electron John - The Drivability Guy

Views: 20,217

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Id: 4iIxAI3XQIk

Length: 50min 56sec (3056 seconds)

Published: Wed Jan 10 2024