Idle problem...can't fix..been lost for days

[TurboDreamzGST]

I have a 98 GST Spyder completely stock and about 35% of the time that I come to a stop such as at a stop light or stop sign my idle will drop to almost nothing n the car putts as if it's going to stall out and if I either give it a few seconds or rev the engine the idle will return to normal. I did 3 boost leak tests on 3 separate days and have no leaks so I did a tune up consisting of spark plugs, wires, pcv valve, fuel filter, oil change and air filter and that did not help at all and I have no check engine light coming on (and yes the light does work ### it flashes when I initially turn the key in the ignition). I'm just completely lost at what else I could check or how to diagnose the problem. Can someone please help me.

 

[TurboDreamzGST]

anyone? Any suggestions at all would b helpful ### I'm at a dead end right now...please guys

 

[Quirk]

Any surging? If so it could be your iac/isc.

 

[RD_Blade]

Could be a hidden hole in your intake. The stock rubber intake hose sometimes cracks causing the symptoms you described.

 

[Fat]

Is your timing good?

 

[BoostFrenzy]

If there really is no boost leaks, it is probably a BISS and ISC problem. First check the resistance of your ISC to make sure it is still good. If it is, then you will need to adjust your BISS because it sounds like it is screwed in too far and not letting enough air into the engine. The procedures to doing so can be found here: VFAQ.com.

Any surging at idle? And your BOV is not vented right?

 

[TurboDreamzGST]

Doesn't seem to be surging when it idling...it holds a strong idle whenever this problem isn't occurring...the BOV was vented when I got the car but I re-circulated it

 

[crash89]

Having the BOV vented will cause it to do that.

 

[just90gs]

Having the BOV vented will cause it to do that.

He's right that will cuase it to do that.

 

[RoninEclipse2G]

the BOV was vented when I got the car but I re-circulated it

Uh, he seems to have fixed this issue guys.

 

[TurboDreamzGST]

thanks ronineclipse2g at least u saw that I did say that I already re-circulated my BOV

 

[EagleTalon1993]

I had a similar problem with my 1g here it was a vacuum leak in the power brake booster line where the rubber hose had dryrotted, my rpm's would drop initially when I stopped then the ISC would bump the idle up and it was fine until I stopped again.

I would check for good solid vacuum at idle, Mine is a 1g so I am not farmiliar with what your specific numbers should be but that should be easy to find out.

 

[Lofty]

Well. By the end of my post, your problem should be fixed.
Start the car, let it idle, check for vac leaks. If you haven't eliminated your emissions lines on the top of the TB, I suggest you do that, it eliminates the possibility of them leaking.
Lets see lets seee...
Check for vac leaks around your BISS, the rubber o-ring in them can get jagged up and you can leak vac through there. Extremepsi sells them real cheap or you can even get an o-ring from the hardware store.
Check the resistance between the coils of your ISC. This seems to most likely be the problem but incase it isn't...
What are you idling at normally? Sometimes if you just mess with the BISS you can fix some problems you're having.