idle not so good when engine is warm

01-03-2013, 08:22 PM
Hi there. I have a 1988 firebird formula, manual 5 speed tranny and a 305 h.o.
TBI injected engine. When it starts from cold, the idle will go to 2500 rpm and stay that way for quite a while(like choke sticking). Then will run ok but has a rough idle when warm and at a won't really quit but seems to not run on all 8 cylinders and rpm's drops below 450 then oscilates to 900 then back down again...engine will then hesitate when i give it gas. The engine temperature is descent but this only happens when engine is warmed up. I did change the IAC valve and I also changed the throttle body gasket because I detected a air leak(using the old carb cleaner trick). I am getting bad gas milage too.I am now a little stumped and wondering if the EGR valve is bad or maybe the O2 sensor...What do you think!!!

Tech II
01-03-2013, 10:49 PM
Does sound like another vacuum leak......

Check for codes? don't need a scan tool or code reader....

Since it idles poorly when warm, does it improve if you spray carb cleaner directly into throttle body?

01-04-2013, 12:10 AM
Thanx for the reply! I did a code check on the ECM via the jumper cable and i do get a stored code 24 but the light never comes on... and yes the engine soon light is not burnt!!! I did not shoot carb cleaner directly in the butterflies... what should I expect? idle up? idle down?

Tech II
01-04-2013, 10:21 AM
If it smooths out, it's running lean.....could be injector(s), vac leak, fuel pressure, etc.

If it bogs down, it's running too rich....

Check that MAP sensor.....

01-04-2013, 02:21 PM
Will check asap... one thing i was wandering about: code 24 is supposed to be the vss sensor but on my v8 vin E it is the map sensor... why? Anyway thank you very much Tech your input is greatly apreciated. Car is now stored for winter, but I can work on it a bit if not to cold or snowy outside...When I figure it out , I will reply...thanx again man.

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