How to interpret fuel injector waveforms (a ScannerDanner Premium video)

okay if you want dektor driver design section 17 purpose of this section is to get you used to looking at the waveforms that you're gonna see with fuel injectors both voltage waveforms and current waveforms there are two different designs two main types of computer drivers peak and hole and saturated swims and basically as we go through this what you're gonna see I'll pull up the picture real quick what we're gonna see is a peak and hold waveform would look like this you see a single voltage spike up here looking up here and the ramp for the current looks like this as opposed to a peak and hold or you see we have two spikes and the ramp looks completely different so the idea really with this is that you understand the differences in the designs to make an accurate diagnosis within the waveform there's a lot of things we can look at in the waveform alright so with all injection the speed at which an injector opens is important to the engineer so when they when they calculate the fuel map and they do everything they need to do and take all your air measurements from all your sensors and then design a certain injector that's gonna have the right volume with the right fuel pressure behind it time in the injector opening is also something that the engineers have played around with how fast in time does that electrical injector oven and so that's kind of where these different designs came from the peaking hole of saturated switch and so I have some of that listed here some other things that play a factor in the time that that injector opens would be system voltage so if you think about an engine that's cranking as opposed to an engine that's running it's not uncommon to see a four volt difference in system voltage so if you're cranking the engine over the starter has a lot of amperage and system voltage is low in and just from cranking well the injector on time is going to be longer just to account for the lower system voltage so computer not only controls the injectors based on of course cranking and temperature and all that stuff but it's also looking at battery voltage for battery voltage Corrections so there's always some type of ignition sense circuit on a computer and that's one of the things that's useful so variations in system voltage the injector resistance and current flow how fast the magnetic field builds these are all just things that need to be accounted for for the fuel injector itself size and flow rate that's a big one right here size and flow rate yeah you definitely don't want to just put any injector in the car needs to be sized for that starting with a on just a generic picture of these driver design saturated sweat speak and hold um it's really about total circuit resistance here and how we're controlling the current flow through the injector is where these terms come from when we use the term saturated switch there's really no limits in the in the driver in the computer as you can see in these two pictures these are both saturated switch then they're just on/off tight drivers we're not limiting the current flow with the driver will turn the driver on will let the current travel through the winding of the injector and it's the resistance of the winding of the injector itself that's gonna limit the current flow generally speaking our saturated switch circuits are 12 plus ohms of resistance so the resistance itself is going to limit the current flow saturated switch meaning we'll just turn it on let the magnetic field build to saturation and then we'll turn it off we don't need to limit the current flow that's where the term saturated switch comes from they also call another name would be a voltage controlled injector I've heard them called that voltage control this is most common is a saturated switch type fuel injector and you're gonna have one we'd be looking at a voltage wave or you're gonna have one voltage spike a peak in hole is different if you look at this internal to the computer or the driver it's a little bit different of a drawing but what that's showing is that is showing a driver that is capable of limiting current flow so this driver kind of throttles if you say if you want to call it um it controls the amount of current flow through the injector and generally speaking these would be um you know 1 to 2 ohms the resistance would be your peak and hold type circuit so they need some type of current limiting to prevent too much current flow and heat and burning up the lining of the injector so on a peak and hold we need to add resistance to the circuit to prevent the system from burning up now why did they do these two designs why have they been experimenting with them is the time it takes for the fuel injector to mechanically open so from the time it from the moment the transistor turns on to where the magnetic field builds strong enough to where the mechanical piece inside the fuel injector opens the time they've been experimenting with that and that's what a and B is in this picture a would be the transistor turned on and B would be the moment that the mechanical pintle moved with the fuel injector and you see that this first design between a and B so we're just looking at the time between a and B again time between a and B here and then the time between a and B over here um Honda use this this design this is actually a Honda design from what I've seen where they use what are they call series resistors in front of the fuel injectors so it's still a high resistance circuit but they're using a low resistance injector so it almost looks like low-resistance injector here but this is a low-resistance injector here on the peon hold what is the difference with Honda is they put a resistor in front of each injector which combined with the injector itself makes it a high home circuit so the resistors limiting the current flow of the Honda's and why they did it that way as you can see in the picture the Honda injector opens faster in time than a conventional saturated switch injector with no resistor in front and a high resistance injector itself that's what they're doing I'm not the engineer I did make it I don't understand the whole time thing most of the cars are pretty much done most of the course that you're gonna work on are done like this so it's just the time factor that they built in in the fuel map but we need to allow more time for this to occur but that's where you know engineers have been changing this over the years on what we saw what we see on the peak in Hall work so we're looking over here what we see on this peak and whole design is this guy opens the fastest the time between a and B is the fastest and the reason it opens so fast is it builds a magnetic field very fast because the current flow is much higher and it's a low resistance Goulet now the problem with that would be when you have longer pulse widths or longer on times that if you were to turn this design on and just give it a ground for as long as you needed fuel it would burn up the windings in the fuel injector so the idea with this one is we'll give it a full ground allow it to have unlimited current flow for a millisecond or two and then once the injector mechanically opens we can weaken the magnetic field and hold it open for a longer period of time we can hold and for as long as we want without burning up the whining that's done by adding resistance to the ground and that's what this driver is doing is it's adding resistance on the ground side of that circuit so it's called a peak and hold because we're going to peak the current flow as noted in this wave one this is actually a current waveform and the hold section which is what you're looking at here peak and hold it's similar to a starter solenoid and that it takes a stronger magnetic field to move the solenoid than it does to hold the solenoids so starter solenoids have pull in and holding windings that on initial crank before the motor starts to spin up both windings are energized and then as the motor spins up one of them is dropped and the other one holds it and keeps the solenoid engaged stronger magnetic field to move a component weaker magnetic field to hold it into place okay so with this with this design what you'll have is two spikes because this is the end of the peak section and this is the end of the hold section so we really have two magnetic field collapses on this design and ultimately that's the most important thing when it comes to this because we're not the engineers we're not designing the circuits but we need to know how to interpret the waveforms peak and hold and saturated switch now warning with this would be if your energizing fuel injectors we've talked about this in section 3 section 3 in my book where we talk about output solenoids and transistor drivers and we went through all kind of tests on how to energize an output whether it's power ground side switched and using a test light to do that or using a jumper wire safely as long as you know the polarity and so I get questions about you know people wanting to energize a fuel injector manually and for the most part you don't want to do that first of all because you can fill the cylinder up with fuel and cause a hydraulic situation but even more importantly when it comes to the peak and hole design if you were to manually energize a peak and hold injector understand that you would be giving it a full ground the whole time you're energizing it and you could potentially burn up the winding in that fuel injector you would not want to manually and energize a peak and hold fuel injector for that reason the computer limits the current to keep the injector winding from burning up okay all right next page so let's break down this let's break down this saturated switch and depth there I have two waveforms up here the red trace is our voltage waveform and the blue trace is our current waveform and this is on one fuel injector something else you want to keep in mind with this picture is my aunt / of my blue trace my current ramp is this note right here 100 millivolts equals 1 and so I'm using a conversion just to get an idea of the amperage on here I should have selected on my scope would have made this a better picture if instead of using a boaters this is actually a 5 amp scale I should have just picked the amp probe setting and then it would have done the conversion for us and we wouldn't have to do that conversion but this picture was done with a voltage plus and minus 500 I actually chose that scale over top of the factory setting for an ant prep because I like my zero line when I use one of the amperage testing I definitely like my zero line off the bottom of the screen case I have my amp probe connected backwards I'll be able to see a negative amperage and some of the factory settings they don't allow you to do that as easily so that's why I chose it like that but in any case 100 millivolts is one end so my current pattern in this blue trace you can see at the peak is around 1/8 that's we're looking at right here a peak average of around 1 amp that's a saturated switch when we shot the video on that Chrysler Maserati with ejector problems if you guys remember we were looking at amperage of around 0.7 of an ampere injector and we knew that that was okay from doing repetition knowing at least an idea what we should be drawing and we said that that was good so around and am just under an amp so what I'm seeing for the most part really would be about 0.7 to 1.0 amps is probably a better number to go by as far as what should it be when you're looking at a saturated switched fuel injector alright so blue trace red trace just to give you an idea of where we're doing this check if you're looking at a fuel injector circuit what you would have is some type of feed there would be a fuse you'd have your fuel injector and then this would be internal to the computer where can we acquire the red trace or the voltage waveform only only on the control wire this is the control wire the wire that goes to the computer this is the feed wire or power wire if you want to hold it to a formula to the red trace you're only going to see that in this leg of the service you have to be connected to the control wire take your meter on a voltage scale connect to the ground and you will acquire this red trace you cannot see the red Bolton's waveform on the feed side it's not possible all you'd see on the feed side of the circuit is a flat line fixed voltage battery voltage on the feed side now it comes to current measurement which is the blue track which is the blue trace you can put an ant probe which is what I'm using on the feed side or the control side either one amperage can be done on either side of the circuit recall that current flow does not change through a simple series circuit it's the same all the way through feed side is going to be the same amperage as the control side what comes in must come out pressure changes flow does not change if you can imagine presser in a garden hose water flowing out of the hose the water that's inside the hose is pressurized the water that leaves the hose is unpressurized but the flow rate would be the same everywhere you would put some type of flow meter it wouldn't matter if you put it at the spicket it wouldn't matter if you put it at the inlet of your house it wouldn't matter if you caught it in a bucket and measured it the flow rate would be the same all the way through so that's what you want to think about with voltage and current that's kind of nice to remember because later what we'll be doing is we'll be removing the fuse installing a fused jumper place they sell those to those fuse buddies they sell those things pico techcom they sell them fuse buddy they're not that expensive check it out you can put an ant probe right here on that fuse buddy and then what we can do if that fuse feeds multiple fuel injectors we can read all of those at the same time remember though we're not looking at voltage when we do it at the fuse box we're only looking at current flow okay so he's a little review on voltage and current waveforms alright so let's look at this waveform and plug in some stuff these are things I look for when I look at fuel injector patterns these are some characteristics I look for and every wave form starting at the red trace over on the left hand side I'm showing that on this line right here looking right here should be battery voltage understand that what you're looking at is the circuit is off right now and again to draw this generic picture and what I'll do this time is I'll draw the transistor as a switch so it is a ground side switched transistor if I'm measuring right here with a voltmeter or scope and that switch is open or off that we're looking at right here the voltage in my control wire is going to be battery motors so we'll call it 12 volts circuit off grant did you have a resistor here which is the injector itself but no current flow no voltage drop so the first thing you can see in a voltage waveform of a fuel injector is you can actually see your feed bolt egde and that's what we're looking at again right here and that number if you look at this picture there's 10 volts here looks like that's about 12 maybe 13 volts somewhere in that range right if you saw five or six volts there during this waveform you have a feed wire problem you have a voltage problem so we can look at that first line to tell us battery voltage the next thing that happens the switch up here is going to close so our driver went from open to closed and so we now gave this circuit a ground and kirchoff's voltage law all that voltage is gonna drop in this circuit right so we should go from 12 down to near zero it's not gonna be a perfect ground because wires themselves contain a certain amount of resistance the block the wires going back to the battery so near ground but what should happen this line that's that's what you're looking at is a clean straight line it just switched on and then the one section down here is where we're focused at and that should be very near ground voltage and what that shows is the driver inside the computer has a good ground remember that everything that grounds into the computer essentially comes out and grounds to the block we call those power grounds computer if you saw high-voltage on an injector ground you could potentially have a bad computer ground there are other causes of that shorted injectors computer trying to protect itself some of that we shot some videos on where you have higher than normal ground voltage but that's what you want to see now from from right here to right here we call this our in dektor on time or pulse width that's the amount of time the injector is spraying it's the amount of time this circuits on at the end of the on time you notice the transistor turns off I have listed listed here as transistors off looking right here and we have this spike and the spike is actually caused by the collapse of a magnetic field anything that has a coil of wire that makes a magnetic field when you turn it off you're going to get a voltage sponge one of the things we can look for in the voltage spike is we want to see a minimum of 60 volts minimum 60 volts and I have that listed up here minimum 60 volts and what that does is that shows you the magnetic field strength of that fuel injector if it only spiked to 20 volts what we would say to ourselves is that fuel injector has a weak magnetic field so the height of the collapse tells us magnetic field strength now there's something interesting with this particular one and it looks like somebody took a pair of scissors and cut off the top of the spike what you would see instead of this if there was no Zener diode dump it off the spike is you would see a spike that would come up and it would peak and come come back down it would literally not look like that I have a few waveforms in my book in other places that show that I've seen fuel injectors spike over 120 volts it's not uncommon to see over a hundred volt spike on fuel injectors but I'm telling you guys to look for a minimum 60 and there's a variable to that and of course it's this this Zener diode dumped off of this spike and essentially what they do again drawing a generic picture is inside the computer where our transistor is we'll just draw it as a switch we'll put a Zener diode right here put this the ground and in this case looks like it's about a 65 volt and so the breakdown point of this of this Zener is 65 volts so if the injectors off we said already our voltage in this leg of the circuit is blocked by the Zener it will not go reverse bias is 12 volts 12 to 14 volts engine running so that diode has zero effect right now with the circuit off when the circuit turns on driver closes we get a ground this drops to near zero so again this Zener diode is not in to play but as soon as that fuel injector shuts off and this driver opens back up and this magnetic field collapses on here you're going to get a very large voltage spike in this leg of the circuit and what that's going to do is it's going to hit this whatever number that Zener is rated at it'll hit that number and it'll bleed the rest of it off the ground and what essentially that was there for is to protect the driver from those large voltage spikes is what the Zener dump did and that will affect your reading that will affect this reading right here I'm telling you to look for a minimum sixty volts but if there's a Zener diode on there it's gonna change that hey question was as long as this spike has this kind of flat top then we're not so concerned if it doesn't hit 60 and that is correct all you're gonna see in the next place so let me jump there real quick there's a next picture that these these ones are only hitting about 37 volts and I'm totally ok with that even though I'm giving you a 60 volt number because you can see clearly that those are being clipped off and really truthfully what this boils down to is experience and seeing multiple hundreds of injector waveforms and getting used to looking at them what we should be doing is checking good ones not just checking bad ones so when we have you know time on our hands we should you know go to our car and connect to the injectors and take a look at what they look like if the car is running fine and there's no problems you can be pretty sure the waveform you're looking at normal so that's plays enough and that is in play here to experience all right back to this so minimum 60 volts bike unless there's a Zener dump it off the spike the next part is really useful I use this a lot I actually have a video on this on the title of it is stuck open fuel injector case study and on this car we had a single cylinder misfire and we pulled up the injector waveform and it's very clear if you watch that video that I am using this pencil hump section as a diagnosis for a stuck closed fuel injector so what this is is mechanical movement through a collapsing magnetic field that actually induces a little voltage kick in a circuit if you can remember creating voltage with magnetism we need a magnet we need motion we need a conductor we have all three of those taking place with the pintle closing there should be a hump right here at the end of that waveform what that shows you is mechanically that fuel injector is closing alright it's one of the main things I use on the mall tech to fuel injectors small tech to remember the mall tech ones GM made they'll sort it out got a couple videos on that to the mall Tech twos the redesign they don't sort out anymore they just stick mechanically so again GM has yet to make a good fuel injector this is where I focus on those cars with single cylinder misfires I'll look at that pencil hump and see all right so down to the average waveform let's take a look and plug this these numbers in now for the average waveform it's no surprise that when my transistor turns on I have the beginning of my current one in the sir right voltage drop ground side swings when the voltage is low current is flowing okay and what we want to see here is we want to see a ramp right away we don't want to see any straight up lines and by straight up lines what I mean is that this waveform look like this that would be the beginnings of a shorted injector okay in the 20 years I've been doing this the only injectors that I see do this are the mall tech ones DN all right early model GM vehicles major problem with sorted injectors that would be a parcel sort as they got worse this line would increase further and then this of course would climb and I've seen them where they'll pretty much be something like that which is a completely sorted condition overloads the driver causes the car to shut down because there were group fired systems but we want to see a ramp anything that makes a magnetic field should create a ramp effect and the reason behind that is counter voltage counter electromotive force that is being generated by a expanding moving magnetic field and again we have the three things we need to make voltage we have a magnet the magnets moving and we have a conductor are we creating voltage as we're trying to magnetize this injector and the answer is yes and that's what causes this ramp of fact is a building magnetic field we want to see a ramp when you see a fuel injector caught current ramping for a reason that's why within this ramp you'll notice and this isn't always this isn't always visible depends on the amount of noise in the car - especially these lower amperage settings when you're under an amp there's a lot of noise when it comes to a probe sometimes but you can actually see a little blip in that ramp and actually what that is again is mechanical opening of the fuel injector so that's not the closing side over here we see the closing of the injector and over here we can see the opening of that deck I've read some books that say the pintle honk that's what they call that the pintle honk should occur 60% of the ramp and I'm telling you over the years of doing this those pumps on the ramp or everywhere they're in different places what I'm concerned about a pencil home would be if I see one that looks different from the other cylinders so then you gotta account for this - is if it looks different was was that dektor ever changed is that the same injector because even a new injector reman or aftermarket component can have a different position on where that humps gonna sit but to give you an idea of what I'm talking about how to use that at the end of my fuel injector testing section I have a case study on a Ford that had a really weird-looking pintle hump so in that section I'm showing how to do a balance test it's actually in Section 18 we'll be getting to it next shown how to do a balance test but I have one with a flow problem and what I did is I plugged in a waveform to show you the pintle humps and how drastically different they looked with that one injector that was flowing differently so we can use them as a guide but you put a number in where that pumps going to occur so we have a saturated switch we let it go full ground the whole time no limit in the driver we shut it off that's where we get our spike no coincidence at the same time we drop off our current flow that's what a current ramp pattern should look like okay voltage waveform in red current waveform in blue next page peak and hold I have to be honest with you I don't see these too often anymore I have to say that the throttle body fuel injected engines all use the peak and hold injector on the GM CPI that central port injection the early design with the one injector not the later design with multiple injectors but the central port injected system DM used had the peak and hold injector in it so you would see something like this this waveform was actually taken off of a TBI a GM TBI system a dual point TV I had two injectors that's what this picture was taken off I think I can't remember it could have been a Dodge Omni too early TBI I didn't have too many of them but this is what they look like um same kind of characteristics voltage waveform on top and the red current waveform at the bottom in blue you can see the difference in the ants scales for this and this one should have picked on the last one instead of doing the hundred millivolt for one amp conversion so keep in mind if you guys go through my book miss any of my amp probe pictures that you see that is the conversion for them if I didn't have it marked already 100 millivolts is one in okay um in other pictures this is much better you see my average scale setup already so that scope does the calculations for you basically and you can see clearly that this peak is over four amps just over four and I have about a one amp hole so numbers you want to remember saturated sweats fuel injector generally draws around 1 amp of current where a peak and hold injector is going to be 4 amps on the peak in 1 amp on the hole those would be numbers you want to remember but the same characteristics we have our off section up here so we can see battery voltage something interesting in this waveform I wanted to point it out because you will see it on cars is my black arrow is kind of interfering with that but you see some hash in the voltage waveform right here and we actually see an upside-down inverted coil current ramp pattern right there what you need to understand is a lot of our vehicles share power feeds between the ignition coil and the fuel injectors and what you are seeing is feed back into that injector circuit it's completely normal it's supposed to be there a lot of guys will look at that and think there's a problem in the injector circuit not understanding that a collapse of a primary magnetic field we have 300 400 volt spikes in the primary you're going to get some feedback into that injector circuit when that can be crazy is that higher rpms and when you're looking at multiple waveforms sometimes this fight can end up being inside of this pattern depending on rpm and if you're looking at all of them or only one of them and man can that throw you off because now you've got this weird waveform within your waveform you just need to understand that you have a voltage spike from that ignition coil that's being shared with that fuel injector so you got a coil firing in a different place for a different cylinder at the same time you have a injector firing for a different cylinder that isn't on its compression stroke yet it's on its intake stroke and they can end up being the same so look for that be careful with those files transistor on nice clean line notice that my ground voltage is higher on this one I've read a lot of explanations on why that is just let's put it this way there's a lot of amperage on that ground compared to the other injector isn't there I know I think about like this when we talk about sensor grounds I always give you a number 100 millivolts or less for a sensor gram and the reason I give you that number is sensor grounds they don't carry any measurable amount of current flow you're talking about micro amps of current on a sensor ground so what you could think about is is that ground really being loaded with current and heat then the answer is no so your voltage is going to be much much slower on low amperage circuits when you're talking about ground voltage the higher the amperage you go on a circuit the higher your ground voltage is going to be fuel pump grounds 400 500 millivolts is not uncommon on a fuel pump ground because you're talking 10 amps of current flow on some of those take our last picture with our saturated switch injector and it was only drawn 1 amp as opposed to this one in this peak section drawing 4 amps does it make sense that that ground is carrying a little bit more load and it's probably heating up the circuit a little bit more with that kind of current and we're getting a rise in our ground voltage for that reason you will see that characteristic on peak and hole injectors it's just higher current flow that's still a good ground you know really as notes as noted by the height of this this peak section that's where when we turn this on we're giving this thing a full we're giving this thing a full ground not limiting it at all it's a full ground during the peak sex and that's why our efforts jump so high at that point you see a voltage spike because what happens the transistor switched what it was doing and it's now limiting the current flow and so if we're gonna limit the current flow we're gonna get a magnetic field collapse it's not a full collapse but it's enough of a collapse to give me a pretty big voltage spike and that's what's causing this and of course we have a zener dumping this one off of 35 volts but the injector still spray so you're on time if you look at this you're on times from here to here pulse-width so what we see for the remainder is this hold section right here the injector is still on it looks like it returned to battery folders but it didn't it's actually a few volts below battery voltage 1 or 2 volts below that battery voltage during that hold section so if that's a ground side switched circuit and it is we could say that here in the peak time we have a full ground and we could say in the whole time that we have a partial ground the computer added resistance to the ground right which made the voltage rise on that ground circuit you could also say that this is an intentional bad ground that's what a bad ground would look like if we didn't want it to be that high voltage it's an intentional poor ground that's how we're limiting the current flow of this fuel attack peak and hole all right what was a longer pulse wave look like I missed that let's go back paste what would a longer pulse width look like here it would simply be a ramp right that would extend and a voltage waveform that would extend so this is what your longer on time would look like just the waveform opens up what would a longer pulse width look like on a peak and hold is only this section increases and oh and what would happen in here is the two spikes will separate themselves so the peak time is the time that it takes to build the magnetic field open the fuel injector that doesn't change stays the same but when we change the pulse width what we change is the whole time that would be a small pulse width and this would be a very large long pulse width the whole time so the two spikes will separate from each other you get a snap throttle test you're watching this that's what you would see the only time that you would see the whole section changed sorry the peak section there is a time that you'll see variations in the peak and it's during cranking when we're cranking the peak time will be longer because battery voltage is low so they'll increase the peak time to get that deck there open up real fast if you ever did one experiment with a play around with it check it out during cranking take some measurements and then check it out with it running do some snap throttle you'll notice with the engine running our peak time never changes the only time peak time changes is when we have battery voltage changes and that would be cranking in this case so P can hold peak current hold the current it's about controlling the temperature of the winding if we kept it at 4 amps the whole time we burn up the injector whine you won't see too many of these but they're still out there and they're gonna be good to talk about it we still have our characteristic of our pencil hump right here so we got a little hump right there and it is visible I have a case study of this in the next chapter we'll get to it I have a case study of a peak and hold injector where it's stuck closed and I'm showing you these waveforms whether it's ticking closed somewhere within this current ramp is the opening time of the fuel injector it's not really visible and I'm pointing that out in this case study I have a couple zoomed in pictures of a stuck closed one and what I did is I showed you a zoomed out picture like this and then what I did is I zoomed in on on this side and I zoomed in on this and I showed you the characteristics of what we're looking for for a sticking fuel injector on a peeking hole that's in Section 18 one of the case studies I have in there and this is just a review of what we talked about pique and hold driver you guys can read that on your own and saturated switchdriver and it's the same same information that we just talked about so that this should give you a real good heads up on what we're looking for when it comes to injector waveform diagnosis question I wanted to address is the honda version and the question was where is the resistor for the Honda's is it part of the injector and the answer is no um it would be a remotely mounted resistor block of some type away from the fuel injectors is what you'd look for for the series resistor injectors for them for the Honda design so that's it injector designs next thing we're going to be doing is the injector testing section 18 and section 18 we're gonna be talking about all the did all the injector tests that are available to us how to use them how to do a sound test what are your variables with a sound test how to do annoyed light test um how to determine if the lights on all the time or if it's flickering or not on what your causes are also of course injector current and voltage waveforms we're gonna review what we just talked about and I have a whole bunch of case studies sort of intact their stock injectors voltage waveforms current waveforms that aren't right to just emphasize what we look for when we do fuel injector current ramping and voltage waveform testing section 18 coming up next

Channel: ScannerDanner

Views: 69,845

Rating: 4.9170303 out of 5

Keywords: auto repair, current ramping injectors, picoscope, Rosedale Tech Pittsburgh, Rosedale Technical Institute, scannerdanner, how to test a fuel injector, DIY auto repair, Paul Danner, car repair, Fuel Injection, mechanic school, Fuel Injector Driver Designs, auto tech training, scope testing injectors, Auto Tech, fuel injector testing, Engine Performance Diagnostics

Id: 4mut0Lpg5k4

Length: 44min 7sec (2647 seconds)

Published: Thu Jan 19 2012