How to tell ISC is bad??

[WhiteTsiAwd]

Well my car hasnt been running or starting for a few months now. Finally got it started when i found out the MPI fuse blew. Replaced it and blew again. Replaced it and car just stopped running. Didnt blow the fuse. If you would like more info. on it check my last thread I posted.

My new question is how do I know if my ISC is bad? What would it read on the logger?

Any help/info is appreciated.
Thanks,
Cody

 

[DevilSperm]

your problem doesnt sound like you ISC but here http://dmtalon.v8eaters.com/ISC.html

 

[WhiteTsiAwd]

I dont really understand. I said I thought i had a bad ISC. And what you linked to is about a bad ISC. Can you clear it up for mea little bit maybe?

Also, would a bad ISC cause my car not to start and/or blow my MPI fuse?

 

[DevilSperm]

re-read it dude, it tells you how to check it...and i dont think your problem is the ISC but i gave you a link anyway cuz i am nice

 

[WhiteTsiAwd]

I mis-read it. So what do you think my problem is then? Any idea or guess?

 

[DevilSperm]

its too late in the day for me to think that hard.....make sure you cas is on right for sure...thats all i got for now

 

[steve]

I really like the job Jeff Lucius did on the 3s ISC page.
The ISC is the same between the DSMs and the 3S.

To the best of my knowledge you can't test/check an ISC with a datalogger. The ECU only reports where it thinks the ISC is. It doesn't have any direct feedback, only what it can deduce from trying to step the ISC and what happens to the rpms.

Steve

 

[DevilSperm]

the best way to eliminate the possibility of it being the ISC is to just unplug the idel switch...the car will idle higher but it will run http://members.shaw.ca/dsm.1000q/Engineprimer/1G/idleswitch.htm

 

[dspecv]

I have a question on this also. I just got my 91 gsx this weekend. When starting up, it idles at about 2500 rpm until the car warms up, or after driving for a bit. I'm assuming that this is probably normal, but wondered if the ISC may be causing this. I'm completely new to the DSM community.

Thanks,
Dustin

 

[WhiteTsiAwd]

Thats completly normal. Dont worry.

 

[2GeNTSi]

Hmmm my bros 3S has been having a problem that might be due to the ISC as well. Whenever he first starts the car in the morning, the rpms start out low (700) and stays there after it gets to operating temperature.

 

[steve]

I'd look more at the FIAV for cases where the engine doesn't idle up when cold. 3S's have them too.

Unless my ISC or BISS ae really messed up, My ISC opens to 120 steps before and during cranking then closes to 0 while the FIAV causes the fast warm up idle, then the ISC starts opening again as the rpms drop until it reaches 30 steps at warm idle. I may have my BISS off a bit since I switched idle rpms back to 750 but that would only effect then number of steps I wind up with at warm idle here.

Steve

 

[2GeNTSi]

whats a FIAV? I never heard of that.

 

[DevilSperm]

this explains what it is a little http://www.vallotton.com/fiavblockoff.asp study up on this http://vfaq.com/index-main.html and this http://members.shaw.ca/costall/1000Q/ and this http://www.vfaq.net/DSM/mods/10faq.html

 

[forcedpowerdsm]

i opened up my isc to clean it and noticed that it did not have a spring on the inside. is this a differance between the 1g and the 3s isc? or is my isc just missing the spring?

 

[steve]

All the ones I've opened had the spring but sometimes it stays hiding at the bottom of the coil stack. There is a new version of the ISC out that is different from what's in the various ISC pages but I haven't had a reason to take one apart.

Steve