Hello everyone,
I am new to this site, actually first post.

I recently bought a 1989 IROC TPI 5.0 Automatic from the original owner. All paperwork from day one, all stock, super clean. Just a really cool car which I have wanted every since I walked the chevy lots when they were new in 1989!

Car really has no issues except it seems when started (cold) it will idle at 1,500 RPM which seems high. The idle is stable (it does not move around)

It goes into gear with no issues (no slamming or banging) and after a few minutes when it gets hot, if I put it back in park it is idling around 1,000 rpm. In gear, it is 750 RPM and does not stumble, surge, etc. A friend said to check for vacuum leaks but I have a vacuum gauge which read perfect. Someone had recommended running some techron fuel cleaner through it a few times since it has low miles and hasn't really been run in years. I also, cleaned the throttle blades with throttle body cleaner (which were pretty dirty).

So I guess my question is what should these cars idle at cold/hot in park ?

I am sure as the days go on I will have more questions to ask but thats it for now.

thanks in advance for the help. Here is a picture!

 

Welcome to the forum. Very nice car!

I would have to agree with a vacuum leak being that it's that old. Check all the lines for deterioration, back by distributor, egr solenoid, canister and mostly the vacuum ball in the drivers fender. Follow that line one to the cruise control and then it Tees of to the ball. Its sometimes forgotten.

Then if all else, you can follow this procedure and clean your IAC and check TPS voltage. I personally wouldn't want to start fooling with adjustments till you ensure vacuum is tight. Good Luck!!
https://www.thirdgen.org/newdesign/tech/tpimod2.shtml

PS: Finish filling your profile out. It will help other members know what,where,year, and all that.

 

Nice car.

Yeah I'd look at the vacuum lines, too just for general purpose. How many miles? If your car has the factory Multec injectors, they don't play well with strong injector cleaners.

 

Thanks for the replies....

I spent the day tracing vacuum lines and everything is connected, tight and rubber is soft. As stated, the Vacuum gauge reads perfect and after the car warms up, it idles properly with no issues. At cold, it idles with no issues except it starts at 1500 rpm and then goes to a normal speed after it is warmed up.

Car has 90K miles on it and the injectors were just replaced about 5K miles ago. The TPS readings are in spec and the IAC is cleaned and operating correctly.

I guess for now I will not be too concerned about it but thanks to all for the replies!

 

Drive it and enjoy it then!!

 

Completely normal. If you hit the gas after a 30 seconds rpms should drop back down.