I have a 92 Camaro Z28: 5.7L TPI L98 w/ an auto.

I have a strange problem w/ my idle that started out intermittant, but now occurs 95% of the time. As I come to a stop, the idle will drop too far, sometimes 400 RPM's or farther. As soon as it does this, the idle returns to normal. It only does this once- it doesn't surge. It will also do this if I am moving slowly, and take my foot off the gas.

Other than this, the idle appears normal unless the car is stopped, but still has a load on the engine. An example being backing uphill, around a corner into my garage. Since this problem started it has been difficult to do this carefully w/out peeling out or stalling, whereas I previously coasted into the garage (automatic). Now this process requires a delicate touch on the gas, and the engine seems like it is lugging.

I have also noticed another symptom when I am driving using very little throttle, i.e. 50/55mph in overdrive. It would not be noticeable to a passenger, but the car feels like the gas/power is changing slightly, as if my foot was twitching.


Shortly AFTER this problem started, I replaced: cap, rotor, plugs, and fuel filter. (This did prevent the car from dying at 400 rpms!)

The engine light has NOT come on, and the only code I get is 12. (Not the intro, continously.)

The car starts and seems to run normaly otherwise, but I have studs on, so I'm not sure if my power has changed any.


Any suggestions/advice would be appreciated, thank you.

 

I think the engine is very sensitive to TPS (Throttle Position Sensor) input at part-throttle, especially off-idle. I would check that out.

It is essentially a variable resistor like a volume control on a radio. You know how they get scratchy when they get old? Same thing.


Go through the range of motion of the throttle while watching the resistance with an ohmeter. If it isn't smooth, replace it.

It could also be the idle air control solenoid sticking, cleaning that with choke cleaner may impove things if it is at fault.

 

I've recently picked up an '87 Camaro v6 2.8L for $300.....150000 miles on it, a bit of a fixer upper, but still looks like a fun car Now, i'm very new to the whole working on my car by myself....so try to bear with me.

Problem:
I start the car up and unless i give it some gas....it'll die. After a few minutes of keeping the RPM's up, it drives fine. it'll last approx. 2 minutes idling before dying. So if i stay at a light too long, it'll die. Now, the strange thing is it only happens in gear. If it's in Park, i can let it run till the tank is empty. So yeah, kind of puzzled...

What i've replaced so far:
-MAF
-Fuel Filter
-muffler/tailpipe(exhaust leak)
-cat. converter(was wasted)
-alternator(was fried when i first got it)
-battery(dead from the alternator)

I've been tempted to take a look at the IAC valve....but honestly, i have no idea as to where to look. I'm a total noob to this. I'm used to motorcycles, where everything is easily seen/accessible :P

if anyone could give me some ideas as to where to look, diagrams maybe? My dad mentioned that it sounds like the idle speed is just too low, i've heard someone else say its not getting enough air.....someone else said not enough fuel......HELP! lol