Idle sometimes too fast (after having bunch of work done)

[slipkid]

I had a ton of work done on my '99 GSX a few months ago. The car seems to be running good now but I've noticed that my idle speed sometimes go crazy high, like anywheres from 1500 to 2500. Then it later goes back to normal or stays normal (around 800) other times. Doesn't seem to be any pattern (like hot vs. cold) as to when it goes high. Yesterday it didn't do it at all for instance.

I've been reading some threads up here and see that there can be many different causes for this. I'm not much of a gearhead and not confident I can figure this out myself - and since I had so much work done it I am assuming most likely the problem is related to something that was recently done as opposed to some other part now failing. I mentioned this to the shop that worked on my car and the owner seemed to think this was some kind of new issue, but that seems a bit odd to me.

This is all the work that was done recently below - do any of you guys see something here that could most likely be the cause of my sporadic idle problem, that I should get checked thoroughly before going through some kind of other expensive part/goose chase??

- rebuilt trans
- new clutch / flywheel
- new thermostat
- new waterpump
- new timing chain
- new plugs & plug wires
- new K&N air filter (replacing stock one)
- new belts for alternator, air con, power steering
- new front O2 sensor
- new mid-exhaust pipe

Any advice/clues appreciated. I want to bring it back & ask them to look at it, although it is hard to diagnose if it isn't happening at the time I guess...

 

[92_1g]

Try this link for starters. Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)

Burp your cooling system there may be air pockets

Make sure the coolant lines going to the throttle body are connected.

Remove your ISC (2x 8mm bolts) and turn your key to run position, don't start the car. Your ISC should move and be very audible. then when you turn the key off it should return to it's original position.

Do a search for idle surge or fast idle and you'll see how others have fixed the problem in the past.

Paul

 

[slipkid]

Thanks muchly for that info.

There is a lot there I don't know how to do but maybe I can get the shop that worked on the car to do for me.

Sounds like the ISC (Idle Speed Control) is the most likely source of the problem, but I don't have stalling probs, just fast idle, and not all the time. And just seems too freaky to me that that would coincidentally go bad after all that work, gotta be something related to all that not put together for 100% (or not).

Thanks again.

 

[1gengsx]

You said you had waterpump and thermostat. As was stated above try burping the coolant system. Could be affecting the FIAV.

 

[dyetrying91]

Thanks muchly for that info.

There is a lot there I don't know how to do but maybe I can get the shop that worked on the car to do for me.

Sounds like the ISC (Idle Speed Control) is the most likely source of the problem, but I don't have stalling probs, just fast idle, and not all the time. And just seems too freaky to me that that would coincidentally go bad after all that work, gotta be something related to all that not put together for 100% (or not).

Thanks again.

Check the ISC, Weird stuff happens with these cars for no good reason sometimes.

 

[slipkid]

You said you had waterpump and thermostat. As was stated above try burping the coolant system. Could be affecting the FIAV.

What is the recommend way to burp this system? I've been researching this online and it seems to be something where you open the radiator cap - but this is a closed system, no radiator cap. How do you burp a GSX?

Also, if I had bubbles/air in there, wouldn't I notice crazy problems like I used to have - temp. gauge going to HOT when idling, airco turning off, etc - but I notice none of that now, just sometimes a fast idle.