Persistent EGR problem... not the tube or valve...?

[KILNA]

My truck has, for the last 5 years, been intermittently (but regularly, about 50% of the time) throwing a P0401. I have cleaned out the EGR tubes a half dozen times and replaced the valve & gasket with a new one 3 times. It won't go away.

The tubes are definitely clear. If I remove the valve while the engine is running and put my finger up to the holes, I have forceful blow from the exhaust system into the valve, and great suction going into the engine from the valve.

Is there something OTHER than the tube and/or valve which could cause the P0401 code to be thrown? Did I just get unlucky and have 3 bad EGR valves in a row (they are all different brands, Delphi, Standard Motors, Evan-Fischer)?

I'm at my wit's end, and my registration deadline is looming in a month, I need to put this problem to bed once and for all. Is there a way to reprogram the computer to ignore this and still pass smog...? I know the system is working, the code itself seems to be in error.

[KILNA]

Oh yeah, forgot to mention, I also replaced the intake manifold gaskets a couple of years back too. I probably did that based on this thread:

http://www.vehicross.info/forums/showthread.php?threadid=22081

Could they possibly have gone bad again...?

I see in that thread it could be the Vacuum Control Solenoid...

[Cobrajet]

Good luck! I'm on my 5th EGR valve (original, 3 NAPA, 1 $45 eBay generic), so I feel your pain. I thought there was something wrong with my wiring or computer, but all failures were diagnosed as bad EGR valves. The NAPA valve is (technically) still under warranty, but I replaced it with the eBay valve just to see what happens. So far, so good.

I always used a new gasket, and my tubes were never dirty. Just a little build-up on the pintle of the original EGR, but that's to be expected after 135,000 miles. It's always the electrical internals, not the mechanicals, that seem to fail in my case.

Hope you resolve the issue and pass inspection.

[KILNA]

It's somewhat encouraging that it could just be yet another bad EGR valve... So for you, the cheap ebay one seems to be good (so far), but the Napa ones not so much. Of the 3 brands I went through, Delphi, Standard Motors, Evan-Fischer, none of them seemed to last any longer than the others. I do not know what the brand was on the original that lasted 10 years. Has anyone out there discovered an EGR that might be a bit more hardy than the others?

[KILNA]

Hmmm, it seems there is a GM manufactured ACDelco 214-1080 which is very likely the one that originally shipped with the car (that in turn lasted 10 years). It's the most expensive one I see, but if it fixes the problem for another decade, it'll be worth the money. I'm going to give it a go on a FOURTH replacement EGR valve. Cross your fingers for me, folks!

[mattferguson14]

Fingers Crossed! Let us know how it works, I'm experiencing the same issue..

[Leon R]

I just made a block off plate from Coke can and decided to ignore the CE light :). In my case, I no longer have to worry about the inspection ;). Fuel economy is as good as ever been!

[KILNA]

Yeah, unfortunately the State of California is not as cool with ignoring the CEL codes, especially when I'm hooked up to the emissions machine. :)

[Leon R]

Can you just get it to work every year (or two), whenever you have to get inspection sticker?

[Anita]

My "most beloved" Isuzu mechanic would say not all Egr valves are created equal. He has seen enough VX's through these 16 years to write a book about them. Kilna, if you want another informed opinion on the subject Pm me.

[KILNA]

If that's the case then it would appear that the ACDelco part is the best candidate, I've already purchased one, it's going into Tank this weekend. Made in America rather than China, it doesn't seem to be a brand that people have been commonly using as failing replacements, and is very likely to be the same part that the VX shipped with. The persistent problem of failure after failure only seems to be showing up in later years in the forums here, which means the original part is probably better than what people are using to replace it. Hopefully ACDelco is still making them the same way that they made them a decade and a half ago.

[Hiredgoon]

Yeah, I'm on my fourth EGR valve. This one has less than 1200kms on it and it started throwing the code today.

[johnnyapollo]

I'm on my third. Thus far no problems for the past 4 years or so...and yes it was an Isuzu boxed replacement...

[blacksambo]

Just call Zach at Isuzu Parts Center.com and get an OEM.

[KILNA]

OK, so I went through the tests I found here:

http://easyautodiagnostics.com/gm/4.3L-5.0L-5.7L/egr-valve-tests-6

I translated them into my own doc to make them VX specific:

https://docs.google.com/document/d/1ODwI3yyQt_sKMBYyhyj289PbnG1GqACvhzSrsJzmSeQ/

I have every indication that my current and previous EGR valves are OK based on the tests recommended.

In the process of replacing the Vapor Canister Purge Solenoid (2N1001) (referenced elsewhere here as the Vacuum Control Solenoid)... I noticed one of the hoses was cracked, and perhaps leaking... I think I've fixed this with a zip tie (it was too hard to get to in order to put a metal hose clamp on it).

Also, when my new EGR valve came, I noticed that the ACDelco gasket felt like it was cardboard sandwiched outside of a metal center... my old gasket was just a piece of aluminum. Perhaps there was a leak? I've put the new part in (though I now have 2 old EGR valves which test OK)... I'm clearing the code and seeing what happens. Wish me luck!

[workmeistr]

Hi, has the ACDelco EGR worked for you? I'm throwing P1404 code after replacing mine with a new EGR 8 months ago. Thanks, Bren.

[WormGod]

I'm on my 3rd. Second (ACDelco) failed me within about 3k miles. Ended up going with the more expensive GM (through RockAuto) and it has been fine for the last 15k miles.

[workmeistr]

Cool, thanks. I'll order one tomorrow in anticipation of throwing the code again in about a month.

[KILNA]

So, it's a year out and the EGR codes have remained gone. The EGR valves (both the old ones and the new replacement) all tested fine... the root cause must have been that cracked hose which was causing the bad reading. Make sure all your hoses are secure and not cracked. Specifically, the one that cracked for me was one attached to the lower portion of the right-hand (driver's) side of the intake manifold. I repaired it with a 2¢ zip tie.

If you have a problem that doesn't go away after replacing the EGR valve and cleaning the tubes, then use this troubleshooting guide:

https://docs.google.com/document/d/1ODwI3yyQt_sKMBYyhyj289PbnG1GqACvhzSrsJzmSeQ/

...if everything checks out as per that guide, it MUST be a problem elsewhere, like the cracked hose I found.

The moral of this story is if you get an EGR code, it might not be your valve. It might not even be the input and output tubes for the EGR valve. It might be a hose leak elsewhere in the system, be SURE your hoses are in good shape.

[workmeistr]

Good info., Kilna. I'm only on my first replacement and will probably throw one more valve at it before looking elsewhere. I have never cleaned my tube. I got the trombone cleaning brush but will see if I clean it this time around depending on the deposits on the valve. I'm reluctant to pop off the throttle body as I'm afraid I will introduce a new air leak. Is there a throttle body seal I should have on hand just in case?

WormGod, here's what I see on Rock Auto now; are you referring to the Delphi as the "GM"?

AIRTEX / WELLS 2M1 AdvanTech $80.79

STANDARD MOTOR PRODUCTS EGV589T T-Series $92.79

AIRTEX / WELLS 4F1139 Includes Gasket $97.89

STANDARD MOTOR PRODUCTS EGV589 $103.79

DELPHI EG10175 $112.79

[KILNA]

Good info., Kilna. I'm only on my first replacement and will probably throw one more valve at it before looking elsewhere. I have never cleaned my tube. I got the trombone cleaning brush but will see if I clean it this time around depending on the deposits on the valve. I'm reluctant to pop off the throttle body as I'm afraid I will introduce a new air leak. Is there a throttle body seal I should have on hand just in case?

WormGod, here's what I see on Rock Auto now; are you referring to the Delphi as the "GM"?

Generally speaking, Delphi=GM

There is a gasket, mine was in good shape when I cleaned the EGR from the inside, but you may want to pick one up, they're not expensive:

http://www.amazon.com/Fel-Pro-61034-Throttle-Mounting-Gasket/dp/B000C2G81G/

You'll probably want to check out this thread for info on how to get the throttle body off:

http://www.vehicross.info/showthread.php/26511-EGR-Cleaning-Video

Also, make sure to check the suck/blow on the EGR valve input and output, both before and after cleaning (that way you'll know if you likely fixed the problem). The big hole in the back should have strong exhaust coming out of it, and the small one should have decent suction. I think the most common cause of EGR codes is the smaller tube coming from the EGR valve to the intake, which is far more difficult to clean. It's basically impossible to clean it out right unless you open the throttle body and come at it from the front too, since it has a hard right-angle in the tube only a few inches down. You have to come at it from both sides, even with the trombone brush... it doesn't seem to be able to go around the curve.

[workmeistr]

Awesome info., thanks for taking the time, Kilna. I'm going to order everything in anticipation of doing the whole job. Armed with all the info., not too danting of a task. Thanks to all, Bren.