will unplugging my isc solve my problem?

[jwahl16]

I have been having problems with my idle and have come to the conclusion that it is my ISC motor. After the car is driven for a while it would surge up and down between 1500-2000 rpms at idle (when in park or neutral, not drive). And now when i come to a stop sign or light, my car stalls 80% of the time, and i can't start it back up without giving it gas in neutral then switching to drive. Also, when i turn on my car cold it idles at about 1000, and when i turn on my a/c the rpms drop (aren't they supposed to go up?). I read that I could unplug my ISC and it would fix these problems, is this true? and if so why?

Thanks everyone, Sorry for the long post.


O, and i am also working on getting a multimeter to test the isc.

 

[cjridert1]

Have you messed with your BISS screw at all? These idles are a PITA to get right, there are a few pages around dealing with setting up your idle.

 

[jwahl16]

no its never been touched, i guess i can check to see if it fell out or something.

According to the vfaq, increased airflow (i just put in an injen intake pipe) can throw off the idle, but it also says i need an $1800 tool to adjust the screw effectively, so there isn't much i can do there.

 

[cjridert1]

It wont fall out, but you may/probably need to mess with it. When I was having lots of idle problems I cleaned/rebuilt the TB to help eliminate variables. Check your ISC, boost leak test then set the BISS should get you close.

 

[jwahl16]

Yeah i plan on doing all of that, thanks. Have you ever heard of unplugging the isc and driving the car without it?

 

[EvoRage]

Like others have said, try adjusting the BISS screw, it is located on the top of the throttle body. All you need to do is have the car warmed up then adjust it till it is idling correctly. I was having a similar issue and I removed my ISC, well the entire FIAV actually and just blocked it off. The only issue I have is if the car is cold it will tend to die without a bit of gas, other than that it's fine.

 

[jwahl16]

ok, well when you adjusted the biss did you use that special scanner tool, or what? can i just go and unscrew until it idles where i want it? Remember, I have a 2g.

 

[my98gsx]

run the car and unskrew it, your rpms will rise. You can mess with it until it sounds right. I usually find a point where it sounds good, and then rev the throttle body. Now you can see how it idles after the rpms go up and drop back down. According to how it ran you might have to raise or lower it.

 

[standard235]

On 1g's you have to ground some pins so the ISC stays centered when adjusting the idle via the BISS. Then the ISC adjusts idle according to load (AC/electrical)

 

[jwahl16]

ok well i lowered my idle to about 800 via the BISS (it was at about 1000 warmed up). I also unplugged the isc. I drove the car around for about 5-10 minutes with all types of driving and it didn't stall once. Also, when i put the car in park it didn't have any idle surge.

So for now i would say it is temporarily fixed, thanks everyone.


If i want to clean my throttle body, can i use brake parts cleaner, or should i just stick to carb+Choke cleaner?

Thanks

 

[BK85]

Yeah it's ok to unplug the ISC. I ran my 4g64 for 6mo with it unplugged till I found a replacement throttle body.

The only problem I had with it was now and then the ISC would vibrate to another position and would idle too high. The fix for that was to let the car get cold plug in the ISC and when it got to the cold idle level, 8 or 900 rpm I would yank out the plug again.

BK85