EGR problems + stalling. How to troubleshoot?

[Black88GTA]

So I've had an EGR problem for a couple weeks now, and I think it's getting worse. Is there a flow chart or something out there for troubleshooting EGR problems? Story below:

A couple weeks ago, I started getting a CEL on startup, which didn't last long and went away when I started moving. This happened every time I started my car. The stored codes were 55 and 56 "EGR Temperature sensor or circuit" and "EGR system" respectively. The light was annoying, but didn't seem to cause any real trouble, and there were no obvious driveability issues.

This past weekend, I did my cam caps, cam seals, and crank seal. Now, the CEL is on constantly. Only the same two codes pop up, although I never did clear them. It seems coincidental that the CEL is constantly on now after me messing with it, but I didn't touch any EGR components when I was working.

Now - today when turning into Home Depot, the car stalled. This was after driving for about 25 minutes, so the engine was fully warmed up. It fired right back up when I put it in neutral and didn't act up anymore after that, but the stalling out bugs me. It wasn't running rough or acting strangely or anything - this happened with no warning. Can a bad EGR component cause stalling on a hot engine?

I already plan on cleaning the EGR temp sensor when I have a minute. Anything else I should check / look at? Are these "classic" symptoms of a specific part going out?

The car is a 1994 LSi, with about 104k on it. Any help is greatly appreciated!

[rlutz]

I'd do the temp sensor first. Cleaning is the first thing to try, but it could be a flaw inside the sensor that's causing your CEL. If that doesn't fix it, I'd then go after all the EGR hoses (there's a bunch of 'em to-from the EGR controller). If that doesn't do it, I'd clean or replace the EGR valve itself. If that doesn't do it, I'd replace the EGR controller. If that doesn't do it, I'd replace the EGR solenoid (under the intake manifold, and you might as well replace all the vacuum hoses while you have the manifold off). You might want to just do the whole darn thing at once (except the parts are expensive), depends how much patience you have

I don't see the EGR system causing your stalling problem. EGR is more about fuel economy & emissions. Hope that stall was just a fluke.

[SoCal LS-L]

If the EGR is stuck open, that will stall you out. I just got finished cleaning out every component of my EGR system, including the EGR, with brake parts cleaner. You should remove the EGR itself and make sure the pintle isnt clogged with a chunk of soot.... and that it opens and closes ok with suction applied to the top hose. The vacuum controller right above it should be sprayed out too, with the little fabric filter cleaned too. Its not so hard, just needs a little patience.

Edit: Also, clear your existing codes using the battery disconnect method to reset your system. Your fuel economy will suffer for a couple cycles but only new codes will surface if the MIL lights again. If the EGR were stuck open, I believe you would stall more than sporadically and it would run pretty crappy at low RPM. What you describe sounds more like a MAF or something. There is a small EGR flow chart in the SVX service manual, I dont know if you have it or not, but you can download it from the link in my signature. Good luck man

[Black88GTA]

Thanks for the replies guys...I was thinking about doing all of those lines anyway, but don't really want to take the manifold off Might have to just bite the bullet and do it, I guess. I'll definitely clean the EGR valve itself, as well as the temp sensor, before removing any large parts. Easy stuff first. Do those solenoids / controller commonly go bad?

It stalled again today, after about 25 minutes of driving (just like last time), and fired right back up again after shifting to neutral, same as before. This time though, I noticed that all the "christmas tree" dash lights flickered a second before it actually cut out. So I'm thinking the stalling might be electrical related?? My alternator was replaced a few years ago (has a 2004 dated label on it) and the MAF was replaced with a used one of unknown mileage / age in January. Battery looks fairly newish, although I don't know when that was changed.

[SoCal LS-L]

Originally Posted by Black88GTA

Thanks for the replies guys...I was thinking about doing all of those lines anyway, but don't really want to take the manifold off Might have to just bite the bullet and do it, I guess. I'll definitely clean the EGR valve itself, as well as the temp sensor, before removing any large parts. Easy stuff first. Do those solenoids / controller commonly go bad?

It stalled again today, after about 25 minutes of driving (just like last time), and fired right back up again after shifting to neutral, same as before. This time though, I noticed that all the "christmas tree" dash lights flickered a second before it actually cut out. So I'm thinking the stalling might be electrical related?? My alternator was replaced a few years ago (has a 2004 dated label on it) and the MAF was replaced with a used one of unknown mileage / age in January. Battery looks fairly newish, although I don't know when that was changed.

You dont have to yank the manifold off to get to the solenoid..... it takes some deft maneuvering but you can just remove the intake and get it from the back of the engine bay..... it takes patience though. That solenoid should be good but you can just jump 12V to the terminals while sucking on one of the ports to see if it allows airflow when jumped.

If your dash lights come on right before the stall you should suspect an alternator voltage issue or your ignition switch itself. Those two things can cause a stall AND light up your dash, so start there. Next time you drive you can wiggle your keys back and forth while cruising slowly and see if that makes it cut out...thats the easy way to tell if the switch contacts are faulty, but its not conclusive.

For the alternator voltage.... test it at the battery while you rev it and make sure its not over 14.9 volts or so. While driving you can also modify a cigarette lighter plug to connect a multimeter to, plug it in the lighter socket, then have somebody watch the readout while you drive.

[Black88GTA]

Originally Posted by SoCal LS-L

You dont have to yank the manifold off to get to the solenoid..... it takes some deft maneuvering but you can just remove the intake and get it from the back of the engine bay..... it takes patience though. That solenoid should be good but you can just jump 12V to the terminals while sucking on one of the ports to see if it allows airflow when jumped.

If your dash lights come on right before the stall you should suspect an alternator voltage issue or your ignition switch itself. Those two things can cause a stall AND light up your dash, so start there. Next time you drive you can wiggle your keys back and forth while cruising slowly and see if that makes it cut out...thats the easy way to tell if the switch contacts are faulty, but its not conclusive.

For the alternator voltage.... test it at the battery while you rev it and make sure its not over 14.9 volts or so. While driving you can also modify a cigarette lighter plug to connect a multimeter to, plug it in the lighter socket, then have somebody watch the readout while you drive.

Thanks for the tips on testing this stuff out, I really appreciate it. Come to think of it, I did find a vacuum line on one of the solenoids under the manifold disconnected when I was poking around a few weeks ago (which I reconnected, of course). It looked like it may have been unplugged intentionally at some point, since it doesn't seem like something that would just come off on its own. I might look at that first. So those are open (allow air to flow through) with +12v applied, and closed otherwise, right?

And the ignition switch would make sense, since the first time it went out I was slowly turning into a bumpy HD parking lot. I've got a DMM here, I'll check the alt voltage out if the ignition key thing yields no results.

[SoCal LS-L]

Yeah when you jump 12v on the terminals, it should click and open the passage inside to allow air through.... just connect a vac line to one of the ports and suck while you apply the voltage to verify. The hardest part is getting it back in position to put the bolt back in and getting the vacuum lines back on. Not much room for hands under there and I had to have used every expletive in my arsenal 100X before getting it back in place.

[apocalixto]

actually what is funny is that my car was doing this very same thing for a while. every time i would pull up to a light or turn in somewhere my rpms would act strange and the car would die. the only code mine was throwing was EGR system (i think code 56). after cleaning the egr, no problem whatsoever.
oh...by the way...just joined the 200,xxx club!!!!!

[Sean486]

Originally Posted by apocalixto

actually what is funny is that my car was doing this very same thing for a while. every time i would pull up to a light or turn in somewhere my rpms would act strange and the car would die. the only code mine was throwing was EGR system (i think code 56). after cleaning the egr, no problem whatsoever.
oh...by the way...just joined the 200,xxx club!!!!!

Which parts of it did you clean?

[apocalixto]

egr valve and cleaned out the intake manifold as well.

[Sean486]

I was wondering if anyone had any pictures they could post of the EGR Valve?

[Black88GTA]

UPDATE: I think I found the problem. Traced to crappy aftermarket intake, put there by the previous owner.

Cliffs:
Sensor wires frayed, grounding on metal intake tube
Repaired sensor wiring
Beat tube with sledge until it cleared sensor
Reinstalled, no codes yet.

Full story:
So, yesterday I pulled my EGR temp sensor off to clean it...and noticed that the wires coming out of the top were frayed down to bare wire. The insulation had all been worn away. Weird, I thought. I knew the intake tube was close to it, but didn't think it was touching. So I cleaned the sensor (it wasn't that bad, a little soot / carbon), put short lengths of heat shrink tube around the exposed wires to re-insulate them, a little electrical tape over that, and finally a larger section of HST around that to keep everything in place. I also did a little JB welding on some cracking areas of my intake by the hose connections. I replaced some of the easy to get to vacuum lines under the hood as well, as they were old and brittle and some were loose - including the one to my fuel pressure regulator. And finally, I did the alternator wiring upgrade, which I'd been meaning to do for a while now anyway.

I went to reinstall the intake today after the JB had cured, and noticed that the bottom of the tube was all dented and dinged...right where the EGR temp sensor mount is and the paint had worn away to bare metal. Wait, what? Metal? I assumed the tube was plastic!

It seems that the two exposed wires on the top of the temp sensor were grounding to each other on the aluminum intake pipe, which I think is what was giving me my EGR problems. I think the reason this took so long to show up is that when I got my car, it originally had a cone filter on the end of the aftermarket intake. The filter was sort of bobbing around on the end where the stock air box goes, and not affixed to anything. I should mention that there are two rubber couplers that hold the intake tube to a sawed-off portion of the factory intake, which allow movement.

I didn't like the hot-air intake cone filter, so I reinstalled the stock airbox (retaining the aftermarket intake tubing) and bolted everything up securely. This was about a month ago. Well, when I did this, it put the metal intake tube RIGHT UP against the wires on the EGR temp sensor, and KEPT it there, forcing it against the wires - unlike the cone filter, which was able to move around and didn't force contact with the sensor. Vibrations from driving wore away at the insulation until it was gone, and then it started grounding out and giving me problems. I kind of feel like an idiot that I didn't check / notice that in the first place.

So I beat the intake tube into submission with a 4 lb sledge until there was a nice dimple in it. It's sort of ugly from underneath, but it clears the sensor nicely now. I cleared the codes and fired the car up, and no EGR code yet. Hopefully that's the last of my EGR problems.