Idle Surging

[@TDC]

Hey guys! I've been searching the whole forum for the answer to my question. I've even tried the idle surge FAQ's. I don't know what causes this particular type of idle surge. My guessing is some kind of vacuum leak. Basically what happens is ill be driving my car (1g Talon Turbo) and whenever I put the car in neutral the idle will surge from 1000 to about 1400. Then when I come to a stop it will balance out between 900-1000 and not surge. So what could be causing this??? I am going to boost leak test it sometime this upcoming week.

 

[undefined0000]

Too much air. You can try turning your BISS down, or just unplug the throttle closed switch. Its the blue wire with one connector on top of the TB. Might make your idle high and irrational, but gets rid of the embarrassing surge.

 

[M4s73r]

Id come back after you did you boost leak test. i had this same issue and found several leaks. once those were fixed it went away.

 

[@TDC]

Too much air. You can try turning your BISS down, or just unplug the throttle closed switch. Its the blue wire with one connector on top of the TB. Might make your idle high and irrational, but gets rid of the embarrassing surge.

I thought adjusting your BISS screw without any kind of way to see where it's at (dsmlink) could burn out your ISC motor?

 

[@TDC]

Id come back after you did you boost leak test. i had this same issue and found several leaks. once those were fixed it went away.

Ill be sure to come back after I do the boost leak test!!

 

[DSMTyson]

$20 bucks says you have vacuum/boost leaks. Vacuum leaks cause this issue the majority of the time.

 

[@TDC]

$20 bucks says you have vacuum/boost leaks. Vacuum leaks cause this issue the majority of the time.

I hope your right bud!

 

[undefined0000]

I thought adjusting your BISS screw without any kind of way to see where it's at (dsmlink) could burn out your ISC motor?

You won't if you follow this: 1G BISS Adjustment

I haven't followed this guide yet because I have additional ISCs sitting around, and I plan on hacking the cruise control to do the same thing and have full control over the idle w/o using the ECU. Its only gonna be an experiment though. But I had idle surge when I first got my talon because I had an intake manifold gasket that was installed backwards, bad TB shaft seals and gaskets and bad injector seals. I just replaced the injector seals and the surge is back again , ill fix it tomorrow. A temporary fix is to unplug the sensor that I described above. Be prepared to backfire on decel though, and depending on how bad your leaks are, your idle could spike a ton. If it spikes too much, just leave it plugged in and fix your leaks. You probably have the same leaks I had. Check the lower injector seals and TB shaft seals. Depending on your boost levels and if you're using a paper intake manifold gasket, you might have blown it. I'm going to have to replace mine.