PSA: 1988-1995 stumble after EGR valve replacement

Hoping this helps somebody else who's pulling their hair out (potentially after replacing the solenoid and vac lines). I only found one other GMT400 thread which addressed the issue (gmt400.com/threads/which-egr-valve.60874/post-1290515) and it didn't have pictures, so see attached.

Code 32 on my 1994 Suburban 5.7L. Old EGR valve's diaphram was shot.

Ordered a Delphi "EG10099". The truck stumbled ("hesitated" or "almost died" as some people may describe it) from a stop if I gave it anything less than full throttle. Seemed like about half the Amazon reviews of comparable EGR valves had identical issue.

One Amazon reviewer (tried multiple times to find his review, sorry dude but you sir are a champion) described some examples of these valve having a normal-sized opening in the vacuum hose nipple whereas on others the nipple is blocked off except for a tiiiiiiiiiiny pinhole. He guessed that this was needed on some engine versions/revisions where a normal sized opening permits too much vacuum too suddenly under partial throttle.

Sure enough, my old valve had a pinhole opening whereas the Delphi I installed had a normal size. Local Carquest had a pinhole version instock; installed it and no more problems.

Extra note: after some light research it seems all the manufacturers of these valves sell a pinhole version and normal-opening version under the same p/n for reasons far beyond my feeble mind. If you can only find the normal version, all hope is not lost; break the pinhole nipple off your old valve and shove it into the hose before installing. (Here as well, props to the Amazon reviews dude)

Thank you very much!! Exact problem, with the exact part.

So now I am wondering, Are there also two separate EGR solenoids, and do they need to be paired together ?

name said:

So now I am wondering, Are there also two separate EGR solenoids, and do they need to be paired together ?

Click to expand...

Huh?

Richard

name said:

So now I am wondering, Are there also two separate EGR solenoids, and do they need to be paired together ?

Click to expand...

There are multiple designs of EGR solenoids used. One is a simple EGR solenoid and the other is an EVRV.

This just fixed my hesitation problems. I recently purchased my truck ('92 K1500 5.7L w/177k miles) and was going through replacing anything that looked old. I replaced the EGR valve with a Delphi EG10099 unit and that's when I started running into hesitation issues at low throttle. I searched high and low for answers to this problem on this site and stumbled upon this thread. I replaced the EGR valve again, this time with a Dorman 911-428 which has the smaller opening (at least the one I received did) and completely solved my issues.

One curiousity: Before finding this thread I tried replacing the Delphi unit with the one that came with the truck but that didn't resolve the problem. I just inspected it and it looks like it's an SMP unit and also has the larger port opening. Somehow it was all running fine before I fiddled with the EGR system but again replacing it with the Dorman seems to have resolved all issues.

This topic is really puzzling to me because "back in the day" the EG10099's I bought several of had the small hole, basically a pinhole. I wonder if the current part has changed to fit wider applications, or some of them out there are bootleg?

It's been years but I've put several EG10099's on TBI small blocks with no issue at all. Again though they had the small hole in the vacuum port, not a large one. Even the picture of it on Rockauto shows the small hole:


Richard

Yep, having this same problem. Code 32. Got the EG10099 and runs exactly as OP described after the swap. Here is the up close of the Delphi, sans pinhole. Is the full bore on the nipple just allowing it to recirculate way too much exhaust gas at low RPMs, causing the loss of power and stalling?

Going to swap with the 214-5073 when it comes in and see how that goes. If that works, guess it’s wasted $120 over just a tiny pinhole.

I know some of the confusion is caused by K2500, not recognizing whether it's 7200 or less or over 8500. And if it's got the RPO for Calif emissions which three or four other states require on initial sale, but don't have two year smog checks like we do. There are two rpo codes for federal emissions and one additional for Calif required. And mine used the pinhole model.

If that picture with the large vacuum fitting is Delphi EG10099 then they have clearly redesigned the part or chosen a different part to stamp that number on and have it allegedly fit a wider application list. The original Delphi EG10099 I used to buy several years ago has the tiny pinhole fitting, no telling what else might be different about it.

Richard