When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
So my idle speed is a bit low around 500 rpm and lower while in drive position. I would like it around 650. I found this how to on another website can anyone verify this is correct. Its for a 87 Iroc Z 305 tpi. Thanks! See photo
For the most part... On a stock setup, without other issues, 99% of the time, the throttle stop screw will never need adjustment. It's sealed because most people won't know WTH they're doing trying to adjust it, and it'll end up causing problems. The more likely cause of an idle problem is going to be an IAC valve packed full of carbon and blow by.
Before doing any of that, I'd unscrew the IAC valve, and clean the tip of the pintle with carb cleaner, use an old tooth brush if it's extra funky. Clean out the passages in the throttlebody too. Remove the intake ducting and spray carb cleaner all up in the IAC passages, clean the front AND back of the throttle blades, scrub the bores, etc. What this does is remove the carbon, blow by, and other byproducts that may be blocking air flow through the throttlebody and IAC at idle. When you're done, replace any gaskets you that damaged in the process, and run through the list you posted. TPI cars should idle around 600rpm at cruising temp in Drive. In park they'll usually be a few hundred rpm higher.
The only time I've had to remove the seal on the throttle stop screw, was my 86 T/A, after a 350 swap, bigger cam, headers, blah blah blah. Every other thirdgen I've owned idled perfect after cleaning the crud out of the throttlebody, and replacing one faulty IAC.
Awesome, Thanks I just replaced the gaskets on the intake manifold and when I did that I cleaned the throttle body really good also. New gaskets on everything. I will pull out that IAC and get that cleaned up. Im sure its original and has never been out. other than that the car runs great idles perfectly while in nuteral or park. Its just too low while sitting at a stop light. To the point I just have to put it in nuteral while stopped. Kinda odd. It was doing this before I changed out the intake gaskets too. And yes its pretty much stock. Thanks for the help!
The only way to adjust idle RPM is to reprogram the ECM. Idle speed is controlled by the IAC only. Any attempt to get around this will cause problems (see Drew's post above).
