Idle wont go below 1000rpm. Doesn't surge.

[daddystang]

Hey guys I can't seem to get my car to idle under 1000rpm. It doesn't surge, when I start it cold the idle goes to about 1400 for maybe 20 seconds then comes down to 1150 or so for a few seconds, then drops to 1000 on the dot. I've checked the surging idle checklist even though it doesn't surge. I followed the directions on how to set the mechanical idle. When I did that, it was a little hard to keep running at first, but I was able to get it to hold an idle at about 750-800. Once I connect the IAC and the spout connector it goes to 1000. Maybe a bad IAC? The IAC is less than a year old, but I know that doesn't mean anything. I have that idle plate on the IAC. Anyone use one of those successfully? I just replaced all of the vacuum hoses which didn't really change anything. Any thoughts on this would be greatly appreciated. Thanks in advance.

Regards..

 

[jrichker]

Remove the idle plate and try adjusting the base menchanical idle to 600 RPM.

 

[daddystang]

Thanks jrichker. I'll do that tonight after work, and I'll let you know how it goes.

Thanks...

 

[HISSIN50]

Jrichker's advice is where I'd start too.

Also, I've found that sometimes an IAC will act up all by itself (usually from lack of drive-time). Turning the AC on and off will often (for some reason) kick it in the pants and make the idle hunker down.

 

[daddystang]

Thanks Hissin50, I'll try the A/C thing too. In my search on here I've seen a lot of people clean their IAC with carb cleaner and the like. Years ago I was told not to clean it, because it has a thin layer of grease on the inside that aids in it's operation. Does that sound right? In my search on here I've seen some guys have success with cleaning it, so I thought I'd ask. Thanks guys....

 

[HISSIN50]

I have to agree with you - I personally wont clean an IAC unless it's considered a lost cause otherwise (read: there's not much to lose).

Sometimes they like to totally crap themselves after being cleaned (I use WD40 to clean them if I do. I let it marinate for awhile, dump it, douche with more WD and reinstall). I kinda think WD is less harsh than some other methods.

I like letting it see if it can fix itself without my intervention (like with the AC trick). Sometimes things get balky after some downtime and letting them go for a bit allows them to figure it out (it's an old habit from having cut my teeth on old Euro cars - hiccups were too common. If you tried to fix each one, you'd go crazy and create 10 more issues from the 'fixes'. Not that this is how to treat the EEC IV, but it's where I'm comin from).

Good luck.

 

[daddystang]

Well..... I feel a little silly. I realized a few things today. I have an SCT chip in my car which I remembered, what I didn't remember was that I have it set on a non-adaptive tune. When I had the chip installed and dyno tuned he put 4 different tunes on it, and one was a custom non adaptive tune that the computer can't overide the settings. How I forgot what tune I was on is beyond me.... I went ahead and set the mechanical base idle to 700 on the non adaptive program, and when I connected everything back up the idle went right back to a steady 1000. Then I switched the controller to the stock adaptive tune, and the idle came down to about 900. I turned the A/C on and off a couple times (as per Hissin50's suggestion), and the idle came down to about 800. Good call Hissin.... I have an appointment for another dyno tune next Friday the 15th, and I'm going to see if he can bring the idle down on the non adaptive tune, because it ran a lot stronger than on the stock tune (just a little higher idle). Anyone have any experience with the SCT chip, and trying different tunes with different idle speeds, and such? Thanks again Hissin50, and Jrichker for your suggestions.