RPM goes up and down when idling..

[Falconeer]

Hi..

Just wanted to hear if anyone of you have experienced the same as I do. I just noticed today that when the car is in idle, after it has been driven for quite a while, it tends to increase the RPM. It goes from 750RPM up to almost 1500RPM and then back. It does this a couple of times and then everything is fine again.. It's almost as if the speeder pedal doesn't come all the way up again after it has been pushed down. I have a 1998 Viper GTS and it hasn't done this before.
Does anyone out there know why it's doing that? Is it the cable that might get stuck somewhere or is it just something the engine does once in a while?

I hope it's nothing serious..
Thanks in advance.
Erik

 

[Qualitywires.com]

It might be you Idle Air Control Valve...could be faulty or dirty. How many miles?

 

[GR8_ASP]

Possibly an intake air leak.

 

[Falconeer]

It has almost 39.000 miles..

 

[Fast Freddy]

have you ever changed your fuel filter?

 

[Gerald]

don't listen to anyone here

You have been blessed with idle hang, it's actually very common... Noones figured out how to cure it yet. There are a couple patches...

Trying blipping your throttle..
Flip the A/C on for a split second (that works the best for me)
tighten your return springs on your throttle bodies.
Make sure you throttle bodies are synched correctly.
clean your IAC motor with F.I. cleaner
restrict IAC motor tube with smaller diameter tube

If that fails.. You could always just turn up the stereo.. :thumb:
G

 

[Falconeer]

don't listen to anyone here

You have been blessed with idle hang, it's actually very common... Noones figured out how to cure it yet. There are a couple patches...

Trying blipping your throttle..
Flip the A/C on for a split second (that works the best for me)
tighten your return springs on your throttle bodies.
Make sure you throttle bodies are synched correctly.
clean your IAC motor with F.I. cleaner
restrict IAC motor tube with smaller diameter tube

If that fails.. You could always just turn up the stereo.. :thumb:
G

Ok, thanks..
I hope you are right, because I'm in a fase right now where I don't know if my warranty is valid anymore or not. But the car hasn't acted weird since it actually started.. Sounds strange though but it's true.

Thanks for the responses! Your help is appreciated..
Erik

 

[Martin D]

Gerald is Right on the money! I would follow his suggestions.

Regards,

 

[viper spray]

Clean your IAC first, it fixed mine.

 

[Shanedog]

Clean your IAC first, it fixed mine.

Where is the IAC?