yet another idle issue

[MyBeatGSX]

Yes I did search this, the problem is that there's about 2930487239573453948753 different people all with slightly different idle issues, so none of it is relivant to me...

Just the other day I swapped to a 1G TB. The BISS was horribly out of adjustment. I've been messing with it for a couple days now. This morning it was a little on the low side (650-700rpm), so I gave it a tiny turn and went for a ride. Then it was just slightly high (850-875rpm). Before going out tonight I gave it about a 1/20th turn down. It then idled at 780-820rpm, good enough for me, better a little high than stalling out.

However, after riding around for a couple hours tonight with a decent (if unstable) idle... I made a 1st-3rd gear pull on my way home (like the 3th of the night, 10th of the day). After coming to a stop at the next light, it was back to idling into the mid 600's. Just an FYI, my car has always dropped a few RPM at idle after making a pull (even with the other TB), I don't know if that's normal or not. But of course, after pushing the clutch in when I got in my garage (which requires almost a launch and then an abrupt stop because its on a step hill) it died. I immediately restarted it and it idled in the high 600's for about a minute and then returned to normal ("normal").WTF

Another issue that may or may not be related... On cold starts I have a rediculously high idle (or at least I think so, I've seen Toyotas idle higher though). At immediate start up it idles at 2,500rpm for about 10-15 seconds and then drops to 2,000rpm where it stays for awhile. Idle doesn't level to normal (if you want to call it "normal") until the car is completely up to temperature. This is very different then how it behaved with my old TB. In which case it would idle at 1,500 for about 5-10 seconds, then drop to 1,000rpm and by the time the temp gauge was at 1/4 (or half way to operating temp) it would be at a normal 750rpm idle.

I have no boost leaks. The BISS is adjusted to the best of my abilities without a scan tool. I do have a lightweight flywheel, I know I've heard of stalling issues with these, but it was never a problem before.

I'm wishing I had just stayed with my 2G TB.

 

[donmagicjuan]

Out of curiosity, did you do your boost leak test since this problem developed? My car idled really high like that upon startup after I forgot to reconnect the PCV valve hose to the IM. As far as your BISSS adjustment, it was my understanding that the screw is used to center the ISC in its range of control. Whenever you turn the screw, the ISC should readily compensate and restore the idle to 750 if its working properly, as the targeted idle speed is programmed in the ECU. I would check the ISC first. Regarding the lightweight flywheel, I have an 8.5 lb flywheel and FP2 cams, and I've never experienced a stall, even after a hard run.

 

[MyBeatGSX]

Yes I did the test right after reassembling everything. And that's exactly how I thought the ISC should work, so mine is probably messed up or completely dead.

Thanks for the help.

 

[GVR4592]

Have you tested the ISC? It's a very simple procedure:
http://dmtalon.v8eaters.com/ISC.html

 

[90 GSX]

Sorry to bring up an old thread... but you need to tell the computer where you want it to idle. You do this by grounding the timing adjustment plug and connecting pins 10 and 12 on the diagnostic port inside the car. Then you set the idle with the BISS with all accessories off (including but not limited to fans, power steering, lights etc.). Then the car will adjust by itself to maintain the idle you set it to.