Dipping down below 1k at idle.

[Eagle96TalonTSi]

When I first start the car, it goes up to 1.5 and hums down to around 1.1k. It stays there for a couple seconds then proceeds down to 8-900. At lowest it almost sounds like the car could die but it always comes back up to 1000 and starts the process over.

The mechanic that did my timing said it sounded like a misfire, but ive heard a misfire and its nothing as severe as this. Matter of fact there is no obvious noise the car makes indicating a mechanical issue. Its just the idle dipping down and sounding like the car is going to die.

Have the idle adjusted? As ive heard the idle can be a problem with these cars. Or start looking for a misfire?

 

[Altoids94]

Your idle should be around 800 rpm.

 

[Eagle96TalonTSi]

Does your car dip down and sound like its going to die every couple of seconds?

 

[Jonny J]

Your car should idle at 750-800 rpms when its warmed up.

 

[Spoolin92GSX]

Sounds like a pretty good sized vacuum leak to me, have you done a boost leak test to rule that out as a possibility? Could also be an IAC/FIAV issue.

 

[Ravenous]

My car used to do the same thing and I found out the VSS sensor wire had been cut. Fixed it and it fixed the problem, bear in mind I have a 1g so I don't know if the 2g is different.

 

[Eagle96TalonTSi]

Sounds like a pretty good sized vacuum leak to me, have you done a boost leak test to rule that out as a possibility? Could also be an IAC/FIAV issue.

Care to elaborate on what IAC/FIAV means?

 

[Spoolin92GSX]

Care to elaborate on what IAC/FIAV means?

Sorry, I have a habit of using abbreviations too much. IAC is your idle air control, it's a little stepper motor inside/underneath your throttle body that varies airflow past the throttle plate to control idle speed. FIAV is your fast idle air valve, coolant runs through it to allow more air (higher idle) during cold starts; as the coolant warms up the wax melts and closes the opening to lower the idle to the normal 750 +/-50rpms. Although not extremely common, these can go bad and cause major headaches chasing a bad idle.

Have you done a boost leak test, just to be sure?

 

[keveka2]

mine does it when the vent on the valve cover where the pressure valve connects to the intake behind the fuel rail..

 

[Eagle96TalonTSi]

I let it sit and idle for 10 15 min while I vacuumed it out a little and it sounded a lot better. Stayed more consistently at around 750 rpms and never sounded like it was about to die.

As far as boost leak, idk. I have pull aftermarket IC piping, none of that hose and cloth looking boo boo stock piping .

 

[Spoolin92GSX]

I let it sit and idle for 10 15 min while I vacuumed it out a little and it sounded a lot better. Stayed more consistently at around 750 rpms and never sounded like it was about to die.

As far as boost leak, idk. I have pull aftermarket IC piping, none of that hose and cloth looking boo boo stock piping .

There are still PLENTY of opportunities for leaks . Sounds like your fuel trims just needed to adjust, might have gotten lucky

 

[Eagle96TalonTSi]

Youre right. Ill have to do a boost leak test. Honestly I think I hear a whistling under the hood while its idling. Kinda sounds like its coming from the CA intake but idk.

 

[Spoolin92GSX]

If your BOV is vented that could cause issues too, they tend to leak at idle. Mine whistled very slightly at idle before I adjusted it (Greddy Type S) but if it's recirculated it won't make a difference.