Idle Surge help

My car is finally on the road and it runs great, thanks to everyone on here.

From the beginning the car had an idle surge, It's around 900rpms to 1600rpms and never goes away. When the ac is on it stay stable at 2000 rpms yet after about 5 mins. it surges between 900 and 2000rpms. Now on vfaq things that can resolve the problem are egr block, isc failer, biss screw adjustment/ replacement. The car has vpc if that matters. I unplugged the isc to test it, vfaq said it should change the idle pattern, nothing happened. Egr blockoff only resulted in 3 stitches from drilling a piece of aluminum into my thumb, I called it /ubbthreads/images/graemlins/bawling.gif. Biss is all the way in.

What now. /ubbthreads/images/graemlins/confused.gif

 

[524of1000]

It could also be an intake/boost leak in one of the pipe after the MAS. Do a boost leak test and fix any that show up. I had some leaks near the throttle body and it was causing surging.

 

running vpc...but how do I do a boost leak test. break it down please

 

[WaRrIoRs16]

Check your capacitors for leaks. One of the caps sit right over top of a trace for the ISC drivers. It leaks and causes that trace to short and blow out, in turn it burns up your ISC drivers. With those drivers gone, your ISC will not be able to function properly. It's a simple check to do.

 

[524of1000]

click

 

Mine ended up being the throttle body shaft seals. Run a BLT and you might find the cause.

 

[Galactica]

I know I'm a noob to these cars... Can someone clue me in to what the ISC is?

 

[KiNgMaRtY]

I am battling a current idle problem myself. This link should help solve your problems

click

 

[IncorpoRatedX]

have you grounded the diagnostic plug and set the base idle? the BISS shouldn't necessarily be all the way in..

 

[Eaglesfly]

Quoting Galactica:
I know I'm a noob to these cars... Can someone clue me in to what the ISC is?



Idle Speed Control, its a stepper motor on the throttle body. It can often cause idle surge when it goes out.

I would look at the ISC itself and make sure its functioning properly.

 

[AnotherNewb]

Your first step should be a boost leak test and testing the isc with a multimeter. Also inspect all turbo inlet pipes. Im willing to bet that you have leaking injector seals, tb shaft seals and probably a busted intercooler pipe. Do those then check back.

 

[Galactica]

Quoting Eaglesfly:
Quoting Galactica:
I know I'm a noob to these cars... Can someone clue me in to what the ISC is?



Idle Speed Control, its a stepper motor on the throttle body. It can often cause idle surge when it goes out.

I would look at the ISC itself and make sure its functioning properly.



Thanks much. I figured it must be something like that, but I'm used to an IACV, Idle Air Control Valve. I must have a very similar issue because my idle isn't the same all the time and the car won't hold an idle if the AC compressor is running. Must be losing mine...

 

[GSX_TC]

i had the same problm about a month ago before the shootout, so i just got another ISC and sent my throttle body to steve monroe and throttle bodys .com and got it rebuilt with new everything and when i put it all back together the idle was perfect. so thats what i recoomend