BIZARRE end to the hunting/stumbling idle issue on my ‘95.

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Schurkey

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AC Delco sells like 3 tiers of parts as well. From about the same quality as you would find from the local Autozone's Valucraft offerings up to the OEM part that was produced for your vehicle.

The problem with the AC Delco and most aftermarket EGR valves is in the vacuum fitting itself. The OEM valves have a tiny, metered orifice that slows the EGR opening, where the AC Delco and aftermarket units typically have a wide open vacuum port.
Thanks. Saved me a bunch of typing. I was going to mention both items.

MAYBE this grizzled old Dealership Veteran actually knows something, maybe he crammed on a no-name EGR valve and used a "gasket" under it that totally disables EGR function. Or put a BB in the vacuum hose. Maybe he's got a PROM burner, and tuned EGR out of the program. I'm REALLY suspicious of this "secret" fix. OTOH, if the engine runs good, and doesn't set a code...seems like the "fix" was worth the cost in reduced aggravation, improved performance, and lack of mental-health therapy bills.



For the record, I've bought Genuine GM parts--still in the sealed box--DIRECTLY FROM THE LOCAL STEALERSHIP, that turned out to be bottom-feeder garbage.

Prime example is the outside mirror on my '92 Lumina. Original mirrors were in great condition until SWMBO knocked the driver's-side mirror on the side of the garage door opening. Original outside mirrors were Made In Canada (where the Luminas were assembled.)

Replacement Genuine GM mirror was Made In China, and the black-plastic body was dull lifeless grey in six months, while the years-old original passenger mirror was still glossy black.

"Genuine GM" and "OEM quality" are not necessarily OEM quality. Suppliers change, quality plummets like a paralyzed falcon.
 
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any4xx

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One thing about this that still bugs me is that in all of my messing with it, one of the things I did was to disconnect and plug the vacuum line to the EGR valve in an attempt to isolate it. That didn’t change the problem. And I know that valve was sealing properly. I’m glad it’s fixed, but I’m still suspicious.
 

Erik the Awful

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If you rememeber, @MrPink used to shed a lot of light on this from the inside. AC Delco does carry "GM Genuine" which are supposedly the original parts, but they also have lower tier parts that are bottom-feeder junk, in an attempt to capture that part of the market. You have to be careful which tier you buy from.
 

df2x4

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Not a single EGR valve I see listed for the application costs more than $67 and that inlcudes "GM Genuine (not AC Delco)" ...

I thought the same thing looking at RockAuto, but then I found a different GM part number (19210654) on GM Parts Direct for $90. Searched a '95 K1500 with a 5.7L.

https://www.gmpartsdirect.com/oem-p...5PTE5OTUmdD1zaWVycmEtc2x0JmU9NS03bC12OC1nYXM=

Even still, that's a huge mark-up from the mechanic if that's what he used. I'm guessing he's keeping it a secret mostly because he doesn't want anyone to know how much he over-charged.
 

someotherguy

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One thing about this that still bugs me is that in all of my messing with it, one of the things I did was to disconnect and plug the vacuum line to the EGR valve in an attempt to isolate it. That didn’t change the problem. And I know that valve was sealing properly. I’m glad it’s fixed, but I’m still suspicious.
It's kind of a stretch to assume that because it held vacuum that it was working correctly, or that it was even the correct part for the application. These systems can be extremely picky about the EGR valve, as you have found.

Crazy the price jump for 1 year. For a 96 a Delphi is $128.00 and GM is $155.00.
Totally different part. Vacuum vs. electronic. Some TBI applications use this style of EGR valve, too.

I thought the same thing looking at RockAuto, but then I found a different GM part number (19210654) on GM Parts Direct for $90. Searched a '95 K1500 with a 5.7L.

https://www.gmpartsdirect.com/oem-parts/gm-exhaust-gas-recirculation-egr-valve-kit-with-gasket-19210654?c=Zz1lbWlzc2lvbi1zeXN0ZW0mcz1lZ3Itc3lzdGVtJmw9MyZuPUFzc2VtYmxpZXMgUGFnZSZhPWdtYyZvPWsxNTAwLXBpY2t1cCZ5PTE5OTUmdD1zaWVycmEtc2x0JmU9NS03bC12OC1nYXM=

Even still, that's a huge mark-up from the mechanic if that's what he used. I'm guessing he's keeping it a secret mostly because he doesn't want anyone to know how much he over-charged.
The part # shown by GMPD, 19210654, is also covered on Rock for GM Genuine # 2145073 when you look at the application info. $67.

Richard
 

df2x4

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The part # shown by GMPD, 19210654, is also covered on Rock for GM Genuine # 2145073 when you look at the application info. $67.

I saw that, but wasn't sure if the parts were actually the same or just interchangeable.
 

someotherguy

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I saw that, but wasn't sure if the parts were actually the same or just interchangeable.
It's been way too many years to remember the numbers without receipts to compare to, but back around 2005 or so when I was shopping EGR valves for my '94 Suburban that was pinging itself to death, the small-town GM dealer where I lived at the time sold me a valve with a different part # on the box than the apparent original valve I removed from the truck. I was immediately suspicious. He removed the part from the box and showed me the physical part had yet a different # on it. Proceeded to explain how GM had changed their numbering scheme and blah blah.. anyway the valve worked fine.

That truck had been pinging like crazy due to a completely dead EGR valve and also base timing set very advanced; the bypass wire was hidden taped up in the loom near the PCM. The pic you may have seen me post of the blue dashboard with a pencil pointing to the connector is from that truck. :)

Richard
 

98 Nitro

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I saw that, but wasn't sure if the parts were actually the same or just interchangeable.
That's right they are not necessarily the same thing, always go with the older number if possible.
 
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