I bought my 84 Indy last week and ever since I have had a high idle problem. When warm, the car idles at about 1k. When cold, it idles anywhere from 2k to 3500! I don't know why, but sometimes I'll start it and it will idle at about 2k or a little less, but sometimes I'll start it and it'll idle all the way up to about 3500 rpm. I have no idea what's causing it. I haven't checked for codes yet, but will tomorrow. The car drives ok, but seems to me that it's revving way too high in fourth gear. I'll be on the highway cruising at about 75, and rpms will be at about 4k. I could be wrong but isn't that a little high?

quote Originally posted by fierogreg: I bought my 84 Indy last week and ever since I have had a high idle problem. When warm, the car idles at about 1k. When cold, it idles anywhere from 2k to 3500! I don't know why, but sometimes I'll start it and it will idle at about 2k or a little less, but sometimes I'll start it and it'll idle all the way up to about 3500 rpm. I have no idea what's causing it. I haven't checked for codes yet, but will tomorrow. The car drives ok, but seems to me that it's revving way too high in fourth gear. I'll be on the highway cruising at about 75, and rpms will be at about 4k. I could be wrong but isn't that a little high?

Check the tube that goes from the egr to over near the throttle body.. They break a lot and cause stuff like this. ( one of mine did, bought a real nice flexable tube from the fiero store and never had a problem since, Will do the same when it breaks in my other fiero. )

Just checked for codes and got none.

quote Originally posted by fierogreg: I bought my 84 Indy last week and ever since I have had a high idle problem. When warm, the car idles at about 1k. When cold, it idles anywhere from 2k to 3500! .... The car drives ok, but seems to me that it's revving way too high in fourth gear.

My Indy has an intermittent high idle also, but you have two separate things here. Idle means that your car is in neutral and the engine is running. The engine is free to rev at whatever speed the ECM, (through the IAC) tells it too.

In 4th gear, unless your clutch is slipping, your engine speed is determined by your speed and gearing, and nothing else. If you have the 4:10 gears, (which I believe all Indys got) your engine revs in 4th gear are what they are. Unless you swap trannys it won't change.

As for your Idle, I would check the IAC. Also check the Throttle position sensor, make sure it's not hung up. Also look for loose or cracked vacuum hoses. Almost anything can affect the idle. I haven't tracked my intermittent high idle down yet, but it only affects the car when it's not moving and the engine is running, which is not that often.

This was my problem. Has been running perfect ever since. Hope it helps. If you don't have Winadl, find someone with a scanner for OBD1.

https://www.fiero.nl/forum/Forum2/HTML/075289.html

Kevin

The previous owner told me that there's a connection in the engine bay that turns on the cooling fan which is not connected. Could this make a difference?

If it is the cooling fan switch, I'm sure it wouldn't make a difference on the idle. If it were the coolant sensor disconnected, it would throw a code. Mine was just making bad enough contact to throw off the reading, but still enough to not show disconnected, and throw a code. Disconnected coolant sensor will throw code 15.

Kevin

Try running the winaldl program , its saves alot of time and guess work.. However I don`t think winaldl supports some of the 4 cylinder Fieros. Check the supported vehicles. You can build a cable also.
http://winaldl.joby.se/
http://www.aldlcable.com/

I'd like to build my own cable, but the instructions on that site didn't really make any sense to me. Any advice?

Strat110 sells them for a couple bucks, if that helps some, I got the one on the site because he sold me a laptop at to good of a deal to pass down. You could try the mall section , hes in there sometimes. The Radio Shack guys (in the back) know this stuff too, you could print off the instructions and run it past them, they have always been very helpfull where I live..

Just checked for codes again and got a 24, vss. But my speedo works perfectly. Could this be an issue with the tps being bad or out of adjustment?

quote Originally posted by Lambo nut: Don't have this set up on the 84 Indy duke. Kevin

I mis-read the year.. doh !no V6's that year..... nevermind

[This message has been edited by User00013170 (edited 09-23-2006).]

quote Originally posted by fierogreg: Just checked for codes again and got a 24, vss. But my speedo works perfectly.

The VSS goes from the speedometer TO the ECM so you can have a working speedometer and no VSS to the ECM. That will definitely throw a code and it could affect idle.

Re-read your first post, from 1K to 2500 to 3500 rpms , is alot , may want to start looking for vacum leaks, if you unplug the iac and there is not changes in the idle, you should look for a vac leak, the CTS sensor can do this as well. A sticking or binding cable can cause this along with a pcv vavle thats shot or plugged up.