Idle surge when starting cold, but after revving a while normal

[RedTurboEclipse]

I have a 95 GSX, stock motor, i have a 1g TB, FIAV still in tact.

When starting the car after not being started for a while, or cold, its as you would expect.. high idle as it warms up, then it will come down eventaully, but then it surges bad. it just drops from 1500 to 1000.

it will stay doing that until i actually drive it or hold the revs for a while at 3k. then it idles perfect at where i have it set at.

then it won't do it again until the car sits for a bit. turning it off and on in a warm state after idle is normal it will be just fine. but the next day, it will be the same all over.

I've tested the isc, replaced a few times, all in spec, checked if throttle sticking by adjusting that stop on the 1g tb which is good. Don't know what else to check.

 

[Geier]

Have you verified the TPS as well as the closed throttle switch are working? Also, check the ISC. Beyond that, I would say a throttle body rebuild.

 

[mirage_david]

I would look at your MAF as well as your ICS. The MAF would be my best bet on your issues as mine did the same thing when I had no MAF and I started my car. Try unplugging it and see if you get different results. A bad ICS will just about have bad idle all the time.

 

[92AWDHX40]

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge) I would start reading this lots of information on idle, and surge.

 

[miguelmcv]

My bet goes to the ICS.
Check that out if is working.
Use the site that (iugrad92turbo) insert to test your ICS.

 

[91gsx123]

mine was acting like that, it was the ics.

 

[empie1]

If you guys could read..you would have noticed he said he tested and replaced the isc. Im willing to bet the problem is the fiav. When the spring is shot, it malfunctions just as you are describing. If you pop off the bottom section of the throttle body (where the coolant lines attach) there is a plastic plug with two holes in it. Grab a pair of needle nose pliars and turn it clockwise until it stops spinning. This is essentially "deactivating" the valve by closing it all of the way. You will have to hold the gas in for 2 minutes or so during real cold start ups (for me its below 40 degrees), but you will never have another idle issue..especially if you eliminate the isc.

 

[RedTurboEclipse]

I THINK EMPIE1 GOT IT ON THE MONEY.

yes i replaced ISC, i checked 2 that i used and they were within spec.

the FIAV is the only thing I have not checked.

a local member also mentioned the FIAV.