I recently had some exhaust work done and got a tuner from Bama. When I put the "performace" tune on the idle rpms wont go below 1800 unless I'm sitting stopped for at least 5 seconds. Even if I start off in 1st then punch the clutch at around 1400 it jumps to 1800-2000 and wont drop. Now, its got me thinking something is off with my car because I've always noticed a very slow idle down on my RPMs. I know our cars have the "hanging rpms" problem but I figured my tune would help. If i set it for the street tune its better but the rpms hang at whatever I push the clutch in at for like 3 seconds then finally starts to drop. Makes shifting weird. If I revert to the stock tune its better but barely decelerates and takes a long time to finally make it down to 1000 then back to idle. I'm thinking it may be my car and not the tune because the more aggressive the tune, the worse it runs. I wanted to see if it could be my IAC valve malfunctioning before I contact Bama about it but was hoping this might make sense to someone and point me in the right direction before I just blame it on the tune since it still doesn't idle down very well even on the stock tune. I also didn't want to run out and get a new IAC or TPS or something without a better idea because I don't believe you can return those if you've tried them can you? I've already replaced my o2 sensors with my exhaust but it didn't change anything. I'm not getting any error codes either.

 

Sounds like the IAC. Remove it and clean it out with carb cleaner or Seafoam. It should idle better after that. Then you can better decide if you think it needs to be replaced.

 

Here is how to test the IAC...

 

Thanks Cliffy. I was looking around at IAC issues on google to see what symptoms were and I found this:

04/28/97
LONG CRANK - STICKING IDLE AIR CONTROL (IAC) VALVE - VEHICLES BUILT FROM 11/1/94 THROUGH 3/30/96

Mine does this! about 50 percent of the time my car takes about 3-5 seconds of cranking to actually fire. Its always done it and no one has ever been able to pinpoint the issue. I wonder if its all related to the IAC?

 

Could also be something along the lines of fuel pressure leakdown. If you turn the key to "on" and then back off without cranking the engine, and then attempt to start the engine does it fire right up like it should?

 

No I've tried that actually. I wondered if it was a priming issue and did the turn on, off, on, off and could hear it prime but it would still crank forever before actually firing.

 

Could be the IAC. If you're going to clean it, try to keep the solenoid part pointing upwards so that you don't get any of the cleaning fluid in there. I messed up my IAC like that. It was acting up, so I cleaned it a couple of times, then it stopped working completely.

 

Got home too late last night to test the IAC but I started wondering if a vacuum leak could cause my symptoms? Trying to get this thing running sound so I can start DDing it again.

 

antwaan,

Although vacuum leaks can cause similar hanging idle symptoms, I think it's your IAC as well. Mostly since your engine takes almost 5 seconds to catch when initially firing up. Without enough air/oxygen, the combustion process can't start. Now if there was an air leak, you'll have unregulated air in the engine, however it should still fire up with a lean mixture.

Let us know how you make out tonight!

Shane

 

It was my IAC valve! I told it off and it looked gummy inside. decided to stop and buy a new one. got it on and it fired right up. I instantly noticed a difference in the idle. I let it sit and warm up then took it down the road and the rpms dropped as I expect them to now.