I have a 91 z28 with a 305 tpi that won't idle until it warms up. Once it is warm, it runs great but kind of rich. I had to replace the ecm and was told that the idle would relearn itself after a couple of run and ignition cycles but it has yet to do so after driving 650 miles. There is a code 32 which is egr but I replaced the egr when I rebuilt the motor so I know the valve itself isn't bad. there is also a code 43 which is esc but the manual said I would get this code if the ecm was replace the idle not relearned. Any suggestions?

 

i am having the same exact problem. but i am also getting code 44 or 54 i cant remember off hand, its the code for o2 sensor left bank(running lean) but smells real rich. i replaced egr valve, spark plug wires, temp sensor, rotor, cap, more then id like to count on vacuum lines!!! now i reset the computer, and got it to put down the road til the check engine light came back on. only code im getting now is that o2 sensor code. but i'm having this eerie felling that its a symptom code and not my actual problem, since its intermittent i always think i have it fixed and then its not. i figured worst case scenario its the brain. ($60-$80 at oreillys) but im not one to throw parts and money at a problem til its fixed. ill keep you updated

 

Alright I can tell you now that you don't need a new ecu because I have replaced mine. I was thinking that it could be an O2 sensor out but since there isn't a code for it I havent' replaced it. Next month I'm going to buy an obd1 scan tool so I can get a live feed from the sensors and also relearn the idle. But I think i have it narrowed down to one of the following: tps, feul pressure regulator, map sensor, or o2 sensor. The scan tool should tell me alot of what's wrong I just don't have money till may. I'll repost when I find out more

 

i tested my throttle position sensor yesterday, it is bad, as you moved the throttle up slowly it would go all the way upto 3.156 volts then cut out. i figured even tho it is bad it measured upto more then half throttle so tech it should work but i was getting desperate and since i get 55% discount at auto parts store it only cost me $20 so bought one put it in, ran fine everything was great yesterday. i just walked out there this morning and now im getting nothing. map sensor is good. and i know its not the o2 sensor cuz now it wont even start, and the o2 sensor doesnt come into play for a while after you start it. i hooked up spark plug testers, one to the center plug in the cap and tested EVERY spark plug. they are good, i went to test the fuel pressure, and after i hooked up the fuel pressure tester to test it i realized that person i lent out my $450(used) tool now the guage doesnt work at all. i cant begin to tell you how happy that makes me. intermittent problems are the BEST. haha.

 

o yea, and are you sure the egr valve is good? it is possible to get bad parts. to test the egr valve just put a metal plate in between the egr valve to cut off the vacuum. if it idles out. then you have a vacuum leak with the egr valve itself or the hose. and if it does that. you are lucky, and im a ******. o2 is good to replace in the begining to rule it out as a problem, but i know its a symptom code with mine. not an error. REALLY WISH I HAD MY FUEL PRESSURE TESTER!!!!(WORKING)

 

Lol I know how that goes with letting a friend use something and returning it broken. But I was planning on getting a fuel pressure gauge to see if the fuel pressure regulator was good or not... do they all cost that much? I haven't even looked at one..

 

i have a 91 z with the 305 tbi. and having same rough idle problems, i disconnected the vaccuum line from the Map sensor (which i know i replaced in april) and the high idle simmers to normal after a short hesitation. what would be causing the new map sensor not to regulate the vaccuum right?

edit: new O2 sensor within a year, also msd wires n e3 plugs, new coil, new pcv valve, just put on a new egr valve and it was throwin code 32 for egr. was thinkin distributor or ecm??? input???

 

Try cleaning or replacing the IAC (Idle Air Control) valve. This part controls the idle more then the mentioned parts in the above Posrs have been replacing.

 

ya i was thinkin IAC and TPS next. almost ready to just disconnect MAP and run without.