Check engine light... EGR valve again??

[scottydl]

When I bought my '95 Burb about four years ago, it had an intermittent check engine light that was diagnosed as a bad EGR valve, although there were no symptoms. Light just popped on a few minutes after driving, every time. Dang those things are expensive, but replacing it fixed the light.

Then last year, and the engine RPM's were surging and jerking when stopped at intersections. Check engine light, code for EGR valve, and another expensive repair fixed the problem. 2 year warranty included.

Fast forward to now, check engine light is coming back on after a few minutes almost every time I drive. No adverse symptoms. Ran codes, and sure enough... EGR valve. Took it back to the shop and they refused to replace under warranty because they said the EGR valve is performing find (despite the code) and they blamed the ECM or BCM (can't remember which) for putting out bad codes. I mean, come on. It's possible but I don't really buy it... unless someone else has had this experience and can advise.

The Burb is running fine at this point... the light just annoys me.

 

[b454rat]

Pull EGR and clean it. Also get some Seafoam. Get engine up to temp, find a vacuum line and put it into the can. Start it up, sucking the seafoam into the engine. Sometimes it dies, sometimes it don't. But with bout 1/2 can, shut it off and let it sit for 15-20. Put everything back where it goes, then start it up. Drive down the road, and mash the pedal. It will clean the insides out. I did this to an S-10 I had, had same issues as you with EGR. Was a different motor, but wouldn't trip light, but would run like ****. I did the seafoam couple times, but the first time I did, driving down road looked like the smoke screen from a james bond movie lol. Cleared it out tho....

 

[scottydl]

I've done Seafoam before as well as manually pulling the throttle body and cleaning it... But it's been awhile, so good reminder to do those things again.

 

[Dover]

When I did the intake manifold on my truck the EGR passage was completely blocked with carbon build up. May want to pull the EGR and see what the passage way looks like.


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[DerekTheGreat]

Seafoam doesn't do much at all, just puts on a smoke show. That smoke isn't carbon or gick being burned off like many think it is, rather the petroleum distillates from Seafoam burning off. At most, I'd run it as a fuel infector cleaner or in the oil to attempt to free up sticky lifters on an engine I didn't care about. I'd never recommend sucking that through the brake booster. When I was a teen, I used it like everyone else did without any results. Then I watched videos from Chris Fix and others who actually scoped the cylinders after using it, before and after. Negligible difference if you ask me. Chris said it worked, but it's nothing compared to what water or (really) coolant does do your combustion chambers after being burned in them for awhile.

 

[Dover]

Seafoam doesn't do much at all, just puts on a smoke show. That smoke isn't carbon or gick being burned off like many think it is, rather the petroleum distillates from Seafoam burning off. At most, I'd run it as a fuel infector cleaner or in the oil to attempt to free up sticky lifters on an engine I didn't care about. I'd never recommend sucking that through the brake booster. When I was a teen, I used it like everyone else did without any results. Then I watched videos from Chris Fix and others who actually scoped the cylinders after using it, before and after. Negligible difference if you ask me. Chris said it worked, but it's nothing compared to what water or (really) coolant does do your combustion chambers after being burned in them for awhile.

I second that, even if seafoam or marvel mystery oil did what they claim I can’t see it having any effect on the EGR system post combustion.
The only thing I use sea foam for currently is through the manifold vacuum line on my Kia Optima to clean the tops of the intake valves. Helps to keep the crud build up down since it’s a GDI engine and the fuel never touches them.


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[b454rat]

It’s not the cylinders that get cleaned it’s all the other crevices that get cleaned. Works for some, not for others.

 

[DerekTheGreat]

No, no it doesn't. If you think running a few ounces of some snake oil over years of caked on grit with no scrubbing/heat is going to work wonders, power to you. Sounds an awfully lot like the placebo effect. I get it, you spend money on something, you see what appears to be a result and so you endorse it. If someone was to take your vehicle while you were away, run that stuff and then give it back to you without your know it, you'd never know.

 

[scottydl]

When I did the intake manifold on my truck the EGR passage was completely blocked with carbon build up. May want to pull the EGR and see what the passage way looks like.

How did you clean that out? And EGR is pretty easy to remove? I know where it's located, but I've never pulled it myself so I want to make sure there's not something in the way that I'm not seeing.

 

[Dover]

How did you clean that out? And EGR is pretty easy to remove? I know where it's located, but I've never pulled it myself so I want to make sure there's not something in the way that I'm not seeing.

I did mine when I had the intake manifold off for gasket replacement, so it was easy to blast/chisel the gunk out. On a TBI engine it’s really easy but on a newer engine I have never pulled one. For a TBI just pull the air cleaner assembly and disconnect the vacuum hose to the EGR and wiring harness to the IAC on the passenger side of the TBI, (removing the throttle body will make it easier to get the bolts off and back on but it can be done with the TBI unit in place) and remove the one nut and one bolt holding the EGR on (should both be half inch). Once it’s off could probably break up any visible blockage with a flat blade screwdriver or small chisel and vacuum out any debris you break loose. I would get a new gasket for it as well but if it’s in good shape the old one can be reused. Re assembly is just a reverse operation. Bolt it back on and hook everything up. And for piece of mind I would do the IAC relearn after disconnecting the wires and possibly bumping it with a wrench. Here is a short video I found showing how to replace the EGR.

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