ISC Replaced Idle 1800 RPM

[ChunkyLover53]

Before today I had crappy idle symptoms. I determined that the best place for me to start was to replace the ISC. I replaced it today, and when I started up the car it looked like a normal startup it went up to 2000 rpms, and I thought slowly it would drop down to 1000 for a cold start but it stayed at 1800. I thought that was odd, so I let it warm up hoping it would go to 750 rpms when warm. Unfortunately it just stays at 1800, is there anything linking replacing the ISC with a change in how high idle is set? Where should I go from here?

Jason

 

[Boostdclips99]

Try setting the BISS screw http://www.vfaq.com/mods/BISS-2G.html. If that dosn't work, you might want to take a look at the TPS, measure the resistance between pin 2 and 4 on the TPS. You should read continuity (0 ohms) when the throttle is closed and open (infinity) when the throttle is open.

Dustin

 

[ChunkyLover53]

I do not have the scanner tool required to perform that, but I have read a few threads where wisemen said that tightening it and unscrewing it 2 rotations is pretty close to where it is supposed to be. I did that and it had no effect on the idle problem.

 

[daren_p]

Did you unhook the battery after you replaced the ISC? If you didn't that is more then likely the issue. The ecu has no feedback on the ISC position, so more then likely your old ISC won't be in the same position as the one you just installed. Resetting the ecu will center the ISC back in its adjustment range & the ecu will have proper control over it again. Even with this done you may have a high idle for abit until the ecu adjusts the ISC to achieve the correct idle rpm. Adjusting the BISS 2 turns in either direction isn't the correct way to adjust the BISS & won't yeild correct results as every setup can be slightly different.

 

[ChunkyLover53]

No, I just unhooked the battery when I was removing the ISC and putting the new one in. Then in hooked the battery back up and that was it.

 

[daren_p]

Well that should have been long enough to reset the ecu so you should be fine there, as long as you haven't disconnected the ISC after you hooked the battery back up (& ran the car). The BISS is designed to be adjusted to get the ISC back into its center of adjustment range, not to change your idle rpms. Sometimes this happens as a side effect, but is not the proper use of the BISS, like some say to adjust. Without the scan tool or DSMLink I don't believe there is any other way to adjust the BISS properly. I'd wait/run the car for abit & see where your idle ends up as it should eventually lower once the ISC has been properly adjusted by the ecu. You didn't post that you changed anything else but make sure you throttle has the proper amount of slack & isn't holding the throttle plate open. As a last resort after you have checked all other areas, screwing the BISS in will lower your idle if the ISC is already at the end of its adjustment range.

 

[ChunkyLover53]

Ok, so I went out to drive my car last night for a while to see if maybe with time the ecu would adjust the ISC back into the propper position for idle. When I opened the door, the battery did not even have enough power to turn on the interior lights. I know that I did not leave a light on or anything that would drain the battery. I jumped the car and it started fine. I drove around for about 30 minutes, came back and shut the car off. When I stepped out the battery was still dead and the interior lights did not come on upon me opening the door. I hooked the battery charger up to it, and it showed voltage way below any of my other batteries that I have charged in the past. The idle is still around 2000 RPMs.

This leads me to narrow down a few things. The alternator is working because my car was fine while driving. The battery is dead, and I probably need a new battery. Something drained the battery, because the day before it was perfectly fine which was the day I replaced the ISC.

The reason I am bringing this up on an Idle problem post is because this behavior is making me wonder if it is possible to have a short in that ISC sensor. Has anyone seen this problem before, or is it possible? After 30 minutes of driving shouldnt the alternator have had enough time to charge the battery at least enough to perform a hot start or turn on the interior lights? How should I proceed from here?

 

[ChunkyLover53]

Has anyone ever seen this problem before?