Unusual Idle, Timing off?

[MissionSk8r21]

Problem:

When I start the car cold:
Idle's way high to about 2k, drops down to 1500, and then bounces up and down as if it were camming. As I begin to drive, between each shift the RPM's hang for a bit before dropping down.

Once its warmed up, it will idle at about 1000-1100, however occassionally when I start the car warm it'll idle like shit (~500) barely staying running.

Ive replaced my plugs/wires and my EGR. I tried to adjust the BISS but that didnt seem to really fix anything, simply just raised or lowered it. I took my timing belt cover off, and noticed the belt seemed old and timing looked to be off by a tooth.

Im grabbing a belt from carquest and I plan to change it this week, my question is, can that single tooth cause all this erratic idle? Or should I be looking into other things such as the ISC?


Any help is appreciated. My car is a 91 GSX, stock turbo, 90k original miles.

 

[propeine]

I don't have the idle problem so much but the revs "hanging" when I shift occurs to me as well. Not real sure why. Also I would recommend getting an OEM timing belt rather than the carquest one. Look into the tensioner pulley, idler, and auto tensioner as well.

 

[90laserRSfwd]

You could try cleaning your throttle body or making sure there's no extra tension on your throttle cable...

 

[talon187]

check for boost leaks id the same issue my thrrole body gasket was leaking bad one tooth off shouldnt affect idel more like boost creep car seems slow. i would also replace your water pump and tensior while your there. but i would say its isc or boost leak

 

[MissionSk8r21]

I changed the belt, and re-timed it. Car runs much better, however still having issues with cold starts. Jumps up above 2000+ rpms, and grinds if I try to go into gear. I wait about 3-5 minutes and it idles around 1300-1400 which makes the car driveable, then once its all warm it sits at 800.

I boost leak checked it, no leaks. I have no CEL's, and car is perfect other then that. Im thinkin of buying a FIAV block off plate but Ive heard alot of problems with that in cold climates (chicago winters blow).

Any other Ideas? Im guessing something relating to the throttle body, ICS? Bad BISS?

 

[throwedgsx]

did you pull the coolant lines off the bottom of the throttle body at all?