Couple of idle questions...

[Pro3racer]

When i start my car, i know my FIAV is working, but when i turn my car on, it idles right up to almost 3000rpm, then drops down to the normal idle surge range, unless it is colder(car sits for a couple hours), then it slowly, i mean slowly, drops down to the idle range, from 3000rpm. I know that is too high, what is my problem? Could it also be my idle surge problem? I have a n/t, so a leak test isn't really a possiblity. Thanks

 

[steve]

If you have idle surge and a cold start idle of 3k, the likely have the same root cause, somewhere you have a extra source of bypass air, be it a leak or a bad part, or a bad adjustment.
Pressure testing works just as well for NAs as it does for turbos. You just have less to check. Make up a cap to fit the throttle elbow and pressurize the intake and vacuum hoses from there.

Steve

 

[Pro3racer]

Ok, thanks, would you recomment a means of capping off one end of the throttle body. Maybe using a something rubber, and some sealent?? What psi do i pressurize it too?

 

[steve]

Ok, thanks, would you recomment a means of capping off one end of the throttle body. Maybe using a something rubber, and some sealent?? What psi do i pressurize it too?

Figure out what the diameter is and make a trip to the pluming section of Home Depo or Lowes to pick up a PVC cap in the right size and a rubber coupler. No sealant needed. Check the VFAQ and search here to see what others have made.

10 psi should be enough. Soapy water will help you find the leaks.

Steve

 

[Pro3racer]

ok, i'll do that, but i have one last question. When i start my car, hot(car started recently), it automatically revs to 3000rpm, holds for about 4 seconds, then drops to the idle surge range. Why does it do this, people look at me when i start the car, and revs so high, so quick, i know i can't be good for my motor.

 

[herm1357]

check the biss screw onj the throttle body, turn it clockwise and see if that helps

 

[Pro3racer]

I have delt with this many times, the biss screw right now is 1/4 of a turn out. Any other ideas?

 

[t0taleclipse]

i have the same problem but when my idle was normal i unplugged the ISC and after i adjusted the BISS it idles fine but only one problem, its cold here now (30 or below) and my car wont idle higher like its supose to when its cold and stalls sometimes. Is this normal? i dont know if my ISC is bad so i figure i'd unplug it when thing were normal. well it doesnt surge anymore but cold starts are a bi***. Is this normal ? or do you guys think its another problem?