the last week Ive been noticing that when Im at a stop light or just sitting in my parking lot the idle is weird. it will be where it normally most of the time around 1000 rpm's but lately it will dip down to 500 and when it does the car sorta vibrates and I can feel it in my shifter. and it as a low chugging sound. could this be a vacuum leak or something? This is my daily driver so I need to lock down whats wrong before it gets worse so any ideas you guys got is a good start for me. thanks.

 

Any codes?

 

I have a 1992 Z28 with the 305 with tune port injection and for about the last year and a half to two years I have been having a problem with the car ideling and also going dead while in gear at a stop. The problem has gotten so bad that once the car warms up it wont even stay running sitting in park. Yesterday I was messing with the car and I unplugged the connector to set the base timing and the car now stays running even in gear with the a/c running, but if your plug the plug back in it wont stay running. any ideas

 

I have changed the ecm, is it possible the prom is bad

 

no codes that Im aware of Im taking it to a shop this thursday to see if its a vacuum leak or something.

 

i am having this exact same problem i rebuilt the engine thinkin that is what what was wrong(it needed it anyways had bad valves and a broken piston but it still ran) and with the new motor i have had so much trouble keepin it runnin in gear but when i unpluged the connector and set the timing it idled fine in gear but once i plug it in it will die even in park sometimes

 

so anything will help i have replaced the coolent sensor iac icm ecm spark plug wires dist. cap and rotor but nothing helped with now i am runnin with the connector unplugged and it runs great i jus cant floor it

 

may be a possible issue with the pick up coil. im having the same issue, runs great with the est by-pass disconnected. i have spoken to people in there with the same issue and when they replaced the dist. (includes a pick up coil) the issue was solved. i don't know this is it because i haven't replaced my dist. yet.

 

i have a similar issue (1992 z28 5.7 TPI), only my RPMs drop at stops when the car warms up. When the car is cold no issues. After driving for a while if I stop at a light rpms are so low that even voltage drops. I thought it was electrical, checked and cleaned all the ground wires, even replaced an alternator. The problem is not constant, if I give it some gas , next stop light RPMs sometimes come back to normal. Are you guys having similar issues?

 

not so much, yours might be a sticky egr. any of you guys getting a check engine light or have you pulled codes? if you dont know how to pull codes w/ out a scanner read this.

GM Check Engine light Codes without a Scan Tool

 

no check engine for me..

 

poor idle when warm points to bad injectors. Grab a volt meter and test out all of your injectors at 200 ohms, you shouldn't have any less than 16 cold or hot.

 

i was kinda hoping it was something simple like vacuum leak or egr. i'll have to check out the injectors. thanks