having idol issues

[Hitmachine101]

ok ive searched and couldnt fine a solid for sure answer to my problem

my symptoms:

when driving and letting the car out of gear and coasting to the stop light the car drops rpms way past idol to literally 0 rmps almost stalls out and then pops back up to idol at 700rpms

she doesnt actually stall -- very rarely does it stall

when driving around town the idle will slowly climb to about 900-1000 rmps but if im on the high way and coasting down a hill she ll sit happy at 700

what could this be guys?
MAF?
ISC?
any other ideas?
im boost leak testing tomorrow to see if i have a leak or not but ive had this problem for some time now

thanks for the input in advance

 

[Blaze2gDSM]

Try search "Idle", the search engine cannot find what you are looking for because you are spelling it wrong.

 

[steve]

Is this a pagan thread?

There are tons of threads on Idle problems. I'm sure one of them might address your issue or at least give you some things to look at.

 

[ceristeare]

did you back out the idol set screw?

actually there are several idol threads don't give up!

 

[Lofty]

Guys, I know this question is beat to death, but there's nothing more frustrating when you have a problem and people are posting useless crap.


This should help you with your idle problems. All of them.
Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)

 

[Hitmachine101]

thanks for the sugestions guys, i was in a hurry posting the thread so my spelling was lacking as you can see

ill take a look at the idle set screw, is this the same as the BISS?

boost leak test came back just fine, no issues there

 

[Lofty]

Check your ISC, and yes, they're the same.

 

[my98gsx]

check for vacume leaks- this could cause your car to surge and eventually stall. If not try raising your throttle body bliss skrew. Raise the idle up slightly intill the problem goes away. I know alot of people who have their car idle at 900 rpm, but ive always had to set my car at 1000-1100. ( i had the same problem you are having )

 

[steve]

I know alot of people who have their car idle at 900 rpm, but ive always had to set my car at 1000-1100.

The ECU is responsible for maintaining the idle speed normally and the 750 +- 100 RPM idle is programming into it. If you want a different idle speed you have to reprogram the ECU.

If you set the BISS to something else you have to driver the ISC/IAC all the way closed (if it's working at all) before the idle will raise. Doing so disables the ECU control and you get all sorts of driveability issues. You also increase the odds of developing idle surge (or decel fuel cut which is what actually triggers the cut off part of surging).

High idle tends to be cause by various air leaks. That's why pressure testing the intake is recommended to start with. If the FIAV or ISC/IAC isn't working from a disconnected coolant lines or bad stepper/bad ECU drivers/Misajusted IPS then you can get surging or dieing when you push the clutch in, or sagging idle when you turn the AC on or turn the wheels.

It doesn't take much additional air to mess the idle up.