Huntin 5.0

Here's the symptoms; replaced stuck egr valve, put runners-plenum assembly back together with new gaskets, torqued to spec, all vacuum lines accounted for, new plugs and wires. Car fires up fine, idles smooth. Until coolant reaches 110 or 120, you can almost hear a click and engine starts to stumble, gets progressively worse within a minute or two to where it'll barely idle. When it starts to stumble it shoots a ton of unburned fuel out of the pipes. It is not shooting any codes, and I have replaced the cts and O2 sensor to no avail. I don't have access to any scanning equipment yet. Also, with engine cold I unplugged the cts and after firing up it immediately started stumbling. Could i have fried the ecu after numerous jump starts after winter storage? The car has 8000 mi on it and was shooting a code 32 for egr system malfunction before i replaced the egr valve. You guys have a wealth of knowledge and any advice or theories would be greatly appreciated. Thanks!!

Grumpy

120 is about the temp for closed loop determination. So if part of the ecm dealing with the O2 has gone for lunch then that would explain things. Jumping with a poor O2 ground I give ya a maybe. If a 1227165 ecm they are known to go to lunch at about anytime, some jump start just might do it, 1227730 alot less likely but a maybe.

Time for getting a scanner or making one. The homebuilts are cheap and easy. 2 transistors and some soldering, and freeware is available. A quick search at the DIY PROM will provide alot of info., and used laptops can be bought cheap.

92 zzz28

About a year ago my car started having a similar sounding problem. It would start fine but its idle was a little rough. After a few minutes it would almost stall if I gave it some gas. And it had NO power. Even when cold it could barely get out of its own way. It turned out to be a computer problem. We think it got wet when the heater core started to leak. Damn moisture will do it every time. I bet if you had to jump start your car many times, that might cause the computer to get unhappy...Its not impossible.

Huntin 5.0

Thanks guys i really appreciate the help. I may replace the ECU as my next step. My local chevy dealer gave me a part number for the replacement ECU that is totally different from the 730s that I see in here. It's 88999196 and it shows up in GM Parts Direct as the ECU. But the other numbers I see in here don't come up. Anyhow, thanks again, can't wait to get her healthy and go eat some Stangs!

92 zzz28

My replacement ECM had some silly number also. I told them the 1227730 number and got one with I think the number you said. If it ever stops raining here I will go an pull it out and check. But I think that is right...

Huntin 5.0

Sounds good, by the way, does the replacement ECU come with a stock prom, or do you have to transfer the old one?

92 zzz28

The one I got had no prom. I don't think they normally do unless you specify needing a prom. Mine was not to expensive either, like $140, if I remember correctly.

Okay, it stopped raining, heres the GM# 88999196

Hope its helpful...

Huntin 5.0

Thanks alot for the info, ordering the new ECU today, will keep ya updated!