CHEVY COBALT DEAD MISFIRE CHECK ENGINE LIGHT FLASHING DIAGNOSIS

[Music] hey guys what's up it's Eric with Advanced love Automotive welcome back to the channel welcome back to another video today taking a look at this 2008 this is a Chevrolet Cobalt it's got the four-cylinder engine the customer complaint is that the check engine light is illuminated it also feels like it's got a really bad misfire now I don't expect this one to be complicated at all really I just kind of wanted to bring you guys along maybe give you some tips and tricks on how to diagnose a problem like this so hopefully you guys stick it out to the end of the video anyway you guys already know how we do this I'm going to start by connecting the scan tool we'll see what codes we got so let me take you guys inside the vehicle I'm gonna go ahead and start this thing up if you guys take a look at the instrument cluster you can see that we do have a check engine light illuminated see it just started flashing what that's telling us is that we have a misfire present at the moment and I can tell you guys right now I definitely feel it the engine is shaking pretty bad and if you pay close attention you might be able to hear the idle surge you might even be able to see it on the RPM needle there yeah check it out you see how it's bouncing around there so we definitely have a misfire I'm gonna go ahead and connect the scan tool now today what we're using is a c-reader elite and this one here is actually specifically made for GM vehicles so I'm gonna go ahead and plug this in like so you can see our tools powering up I'm going to shut the engine off because we really don't need it running for us to read codes however we do need the ignition powered on so I did turn the key on if you guys didn't already notice you can hear that we have an air door actuator over there that's making a bunch of noise it sounds like somebody's trying to get out so I'm going to show you guys how to use this tool in order to diagnose your check engine light so we're going to start by clicking diagnose then we'll click on auto detect and this is going to scan for the VIN number it's asking us if it's an automatic or manual transmission this is an automatic so we'll click on automatic this vehicle does not have stability enhancements so we'll click on that and as you guys can see it is running a Health Report which means it's going to scan all of the modules on the vehicle again like I said guys this thing is specifically made for GM and what's awesome about it is that it is a full-blown professional level GM scan tool in a handheld unit so this will actually scan every module that's on your vehicle okay so this thing finished scanning and you can see it generated a report for us so if we scroll down here you can see that it lists all of the trouble codes that we have in each of the modules so I'm going to start by clicking on the engine control module you guys can see we have seven codes present we'll start up here at the top we have a po171 fuel system lean we also have this po300 engine misfire detected we have a po455 evaporative emission largely detected we have a po463 fuel level sensor circuit high voltage we have a po573 brake switch circuit high we also have a PO700 transmission control module requested malfunction indicator lamp and we have a p1174 fuel trim cylinder balance so we have quite a few different codes here in the ECM some of them may or may not be related of course we got the misfire that's probably going to be the main one that we're going to focus on today because of course often times when you have a bad enough misfire it can cause codes like this po171 to come up but we're going to continue down the line here and we're going to move over to the TCM you can see we have two codes in the TCM I'm going to click on it looks like we have a po573 cruise control brake switch circuit high voltage we saw that in the ECM then we have this po973 one to two shift solenoid control circuit low voltage then if we scroll down here we have the body control module I'm going to click on that you can see that we've got three different codes we have this B 1325 device one power circuit voltage below threshold we have a b 3948 left front turn signal circuit short to battery or open and a b 3949 right front turn signal circuit short to battery or open now if we scroll down here you can see that we also have a few codes in the passenger presence system looks like we have some codes for the turn signals as well we have a code in the radio and we have a code in the remote control door lock receiver so we got some keyless entry codes here and if we scroll down here we also have the theft deterrent module looks like we got two codes a b3055 and a b3935 well I'm not going to really worry about those codes because the key that we have in the ignition seems to work it starts the vehicle up just fine and we don't have any security light present so we're not going to worry about those now the other cool thing about the scan tool is that the report that it generates can actually be shared so if you're connected to the internet through Wi-Fi you can actually email this to your customer which I think is really cool option anyway I'm going to go ahead and back out of this menu I want to go into the engine control module so here we have the menu for the ECM and if you take a look you can see that we have a lot of different options because like I mentioned before guys this is a full-blown GM scan tool so it does have the ability to do bi-directional controls what I want to do is I want to go into read data stream and I'm going to choose misfire data now here we have a list of data pids all of them that are related to the misfires but what I want to do is I want to scroll down and I want to find the misfire counters for our cylinders one through four okay so here we have misfire counter for cylinder number one cylinder number two number three and number four now that I have those selected I'm going to click on OK and here we have our misfire counters I'm going to go ahead and start the vehicle up now let's take a look at the scan tool and you can already see that cylinder number two is definitely where our misfire is happening you'll see that cylinder number one is counting a little bit but you'll also notice that it's not counting as much as cylinder number two now the reason for that is because oftentimes when you have a cylinder that's misfiring bad enough it can cause other cylinders to count erroneously so really what we're doing here is we're going to pay attention to the one that's counting the most the one that obviously shows to have a problem and in our case it's definitely cylinder number two I mean take a look at that we have over 100 misfires on number two and only one on cylinder number one at the moment we're getting up to 200. we got really close to 200 there for a second so yeah our problem is definitely cylinder number two now the first thing I like to rule out whenever dealing with the misfire especially on a four-cylinder engine like this is whether or not we have a bad ignition coil testing our ignition coil is actually really easy to do especially when they're really easy to get to like in our case here so here's our number two ignition coil and what I'm going to do is I'm going to swap it over with our number three now before I take this number two ignition cool out let's take a look at it and see if there's anything obviously wrong with it now I really can't tell much just by looking at this one however in the past I have seen some that were pretty obviously burned or shorted out and you'll actually sometimes see that these things have bubbled over or completely melted in this case the only thing that I see is that it looks like we have maybe some remnants from some type of rodent living down here seeing rodent droppings does make me worry about a wiring problem so just doing a quick visual inspection here and looking for any obvious signs that something was chewing on these wires but just by looking at these I don't see anything obvious I mean the wire loom has broken away however the wires themselves look pretty good so let's go ahead and swap these out now before I do that I'm going to go ahead and Mark an x on our suspected bad coil now let's go ahead and unplug it we'll do the same to number three now before we remove any of the coils I'm going to blow this out with compressed air coils out not before I pop the coils back in I do want to show you guys this is our suspected bag coil and what I like to do is actually take a look at the boot because oftentimes you'll find that uh the coil has a misfire due to a leak in the secondary meaning that the spark is jumping past the boot and so whenever that happens you can sometimes see traces of carbon tracking or sometimes even burn marks from arcing and so looking at this coil I don't see any signs of that however like I said swapping over the coil is a Surefire way for us to determine whether or not this thing is bad so we're going to pop the number two coil into the number three hole and the number three coil and the number two hole then we'll plug them back in now let's go ahead and start this engine up and see if our misfire moved over from cylinder number two to cylinder number three all right so we're back inside the vehicle I'm gonna start the thing up oh it had a little bit of a rough start there and again we definitely have a misfire let's go ahead and take a look at our counters and take a look at that now we have a misfire on cylinders number two and three that is interesting all right guys so just because I'm curious um I think what I want to try to do is move the coil that's in our number three cylinder over here again this is our suspected bad one you can see I marked it with an X and I'm just going to move it over to the number four hole which if you guys didn't know I guess I should have mentioned this to begin with our cylinder order here is one two three four and I guess while I'm at it you know what I'm just gonna go ahead and take the coil out of our number two and swap it over with the coil that was in our number one hole let's go ahead and put this in and we're gonna see if any of these misfires moved all right so let's start this thing back up all right so check it out guys we still have a misfire on cylinder number two but our cylinder number three misfire moved over to cylinder number four all right guys so it's pretty obvious now that our cylinder number two which was our original misfiring cylinder had to have been misfiring due to not only a bad ignition coil but there's something else going on here could it be a bad spark plug a bad fuel injector or maybe a compression problem those are all possibilities however in my honest opinion it's pretty likely that we just have a spark plug that's fouled and so it's possible that because the fuel injector was still spraying fuel into the cylinder that the spark plug got wet and now it can no longer fire so I'm gonna go ahead and pull the spark plug out of the number two cylinder foreign so there goes our spark plug and it definitely looks like it's covered in fuel hopefully you guys can see that but this thing is wet so I'm going to try to clean this up real quick we'll stick it back in the hole and see if our misfire goes away a few moments later all right guys so there's our spark plug after cleaning it up basically what I did was I just sprayed it down with some brake cleaner and I gave it a little bit of love with a soft wire brush and as you guys can see it looks pretty clean I also went ahead and I blew it out with some compressed air just to make sure it was completely dry now I'm going to go ahead and stick it back in the hole reinstall the coil and we'll see if our misfire goes away and it looks like we still have a misfire on cylinder number two interesting all right guys so because I'm curious of whether or not we can even generate a spark here on the cylinder number two I went ahead and I connected my spark tester now you guys may have seen me use this in my past videos basically this thing plugs into the ignition coil Boot and then over here I have it grounded to this nut I've got the adjustment screw set pretty moderately so I'm going to go ahead and move inside the vehicle and crank the engine over [Music] all right so as you guys can see we got a pretty strong spark now what I'm gonna do next is I'm going to back out the screw and I'm going to put it somewhere around 30 KV just to see how strong this spark is I'm going to go ahead and crank the engine over all right so as you guys can see we had a pretty strong spark there now what exactly does that tell us that tells us that the power and the ground getting to the ignition coil is good and also the computer control getting to the coil is there as well so that leaves us with the possibility that we may have a problem with either the fuel injector or a compression issue now one of the first and easiest tests I like to do whenever I'm dealing with the vehicle that I believe has a compression issue is I like to listen to the way the engine cranks now the nice thing about this vehicle is that it has what we call a clear flood mode that means that if we put our foot on the accelerator and push it all the way to the floor and hold it during cranking we can crank this engine over without it starting so I'm going to go ahead and set the camera up on a tripod under the hood I'll crank this thing over and we'll listen to the way it sounds now before I crank this engine over what I want you guys to listen for is the rhythm of the engine on a good running engine we should have an even repetitive Rhythm it should sound something like this now if we had a problem where we had low compression on one cylinder the Rhythm may sound off kind of like this dude and I know it sounds funny when I make that sound you guys are probably laughing at me right now however this is one of the quickest and easiest ways to identify whether or not you have a cylinder with low compression so I'm going to move inside the vehicle and crank this thing over did you guys hear that I think we may have a cylinder with low compression all right guys so I've got my compression gauge connected I'm on cylinder number two for obvious reasons now I'm going to go ahead and set the camera up on a tripod and crank this engine over [Music] all right guys so it doesn't look like we registered any compression on that cylinder at all let me switch it over to the cylinder number three just to compare it all right so I move the compression gauge over to cylinder number three now let me go ahead and crank this thing over and we'll see what we got [Music] all right guys so check that out we have about 100 PSI worth of compression on our cylinder number three we had absolutely no compression on cylinder number two so we obviously have a mechanical problem here all right guys so now that we know that we definitely have an issue with low compression on cylinder number two the next thing we need to do is figure out where we're losing our compression so if you look down here you can see I have my leak down tester what I'm going to do is I'm going to spin the engine over until cylinder number two is on top dead center so I'm going to set the camera up and we're going to watch this screwdriver we'll see if we can get this piston all the way to the top all right so I'm going to spin the engine over I'm gonna try to get it to the top somewhere right about there so now I'm going to go ahead and pull the screwdriver out we'll install the hose I'm going to connect our compressed air now if you look at the gauges you can see that over here on the right hand side our needle is at the set point so I'm going to go ahead and connect the hose to our number two cylinder we got to do this gently to prevent the engine from spinning over now take a look at the leak down gauge you can see that we're running High leak down so we definitely have a big leak here sorry the air compressor just came on so because we're showing a leak down on the gauge over here the next thing we need to do is figure out where we're leaking from so I went ahead and I removed this air intake box because we want to try to listen to see where the air is coming out of and so first thing we can do is listen to the throttle body so I'm going to come over here and I'm going to use my thumb to just open the throttle body slightly and I'm going to stick my ear close to it and listen for air leaking I don't really hear much coming out of the throttle body so I don't think that's where our problem is the next thing we can do is go ahead and pull the oil cap off of the valve cover we'll put our ear close to it and listen again guys I really don't hear much coming out of the crankcase here so it doesn't seem like piston rings are the problem here let's go ahead and check the exhaust all right guys so moving over to the tailpipe let's listen and see if we can hear any air coming out of here oh and I can tell you right now it definitely sounds like we have air coming out of there I don't know if you guys are going to be able to hear it I can barely hear it but you know what I can definitely feel it just by having my hand here I can feel the air flow oh and watch what happens when I try to top it off it's building up pressure I'm gonna let off I really hope you guys were able to hear that but we definitely have air leaking out of the exhaust all right guys so it's pretty evident that we have a leaking exhaust valve on our cylinder number two the next thing I want to do is use my borescope camera to see if we can get a visual on what the exhaust valve looks like all right so moving into the cylinder the top of our piston looks pretty dirty but I don't see any signs of obvious damage to the Piston let me go ahead and switch the camera to the sideways view okay so here we have a sideways view check it out guys if you notice take a look at the valve seat for this particular valve you can see it looks like the valve is not properly sitting in the seat now compare it to the one next to it you can see this one's sitting in the valve see nicely but this other one over here has a big gap it almost looks like this valve is either bent or somehow the valve seat has moved so I'm going to spin this crank over and we're going to watch this valve open and close take a look at the valve opening there I'm going to continue to spin it you can see the valve coming to the closed position the Piston coming back up to the top and right there take a look you can see that our valve now is fully seated there's a big gap between the valve seat and the valve surface well guys that didn't really turn out the way I thought it was originally I thought maybe we had just a bad ignition coil it turns out that our problem is way more serious now whether or not the customer is going to want to put the money into fixing this problem I'm not really sure I'm gonna have to talk to him about it this is not the only problem this car has when we did the code scan we found that we had several codes stored and even some codes for the transmission so even if we fix this problem this car is still going to need a lot more work so anyways I'm going to talk to the owner of the vehicle I'll see what he wants to do and I'll let you guys know tomorrow all right guys so fast forward I wanted to give you guys an update before I ended off the video I did talk to the customer and he does want to go ahead and fix the vehicle so stay tuned because there is going to be a part two where we are going to tear this engine apart we're going to try to figure out what happened hopefully we can get this thing fixed without breaking the bank so like I said stay tuned to the channel because there will be a part two now as far as the Creator Elite scan tool if you guys are interested I will leave a link Down Below in the description if you own a GM vehicle or work on a lot of GMS I definitely recommend checking this out like I said this is a full-blown professional level scan tool for GM vehicles and a handheld unit this thing basically does everything that my 1200 scan tool does but only for GM vehicles that means that not only do you have the ability to read every module on the vehicle but you also have the ability to do bi-directional controls special functions such as crankshaft relearns ABS brake functions such as calibrations and bleeding Kia mobilizer functions such as adding and programming Keys the list goes on and on but if you guys want more information click on the link down below now one thing I would like to mention is that this thing does come with a free one-year update basically what that means is that you can download the latest software into this tool free for the next year now the cool thing is that even after your year is up if you decide not to renew your subscription you will not lose the functionality of the scan tool also I was able to get you guys a discount code I will include that in the link down below anyways guys thank you for watching the video like I always say I hope you found it useful information National educational entertaining if you did make sure to give it a thumbs up if you haven't done so already make sure you subscribe to the channel hit that notification Bell and I'll see you guys in the next one thanks [Music]

Channel: ADVANCED LEVEL AUTO

Views: 34,615

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Id: 5hqcAsaXs2g

Length: 18min 14sec (1094 seconds)

Published: Wed Nov 16 2022