What is this? [Idle Switch]

[avenged5]

So i've been working on diagnosing my idle surge, if thats what you wanna call it. When the car is rolling it surges but when i stop it stops, and the idle is still unsteady. I was messing around with my car today i noticed when i unplug this plug it stops. So my question is, anyone know what my problem is and what this plug is?

 

[jay4725]

I haven't seen that before, do you still have a N/T or did you upgrade?

 

[Barlow]

http://members.shaw.ca/dsm.1000q/Engineprimer/1G/idleswitch.htm

 

[LiquidX]

With a bad idle switch you ecu doesn't know when the car is idling. Fix that and your idle souls steady out.

 

[avenged5]

Thanks for the quick replies! I've been searching around and i cant seem to find a new one. Any ideas on where i can find one?

 

[ramsack]

I would check if it is working before you get a new one. Just hook a multimeter to it, and the other probe to a clean ground, and see if resistance changes with throttle. Closed throttle should be a closed circuit and open throttle an open circuit.

 

[luv2rallye]

It also may simply need adjusting. See page 14-52 of the 1g DSM Backup Manual for proceedure.

 

[steve]

Redherring.

If you disconnect the IPS the ECU doesn't know that the throttle is closed and the check for decel fuel cut fails which is what triggers idle surge. The fact it was surging says that the IPS is working.

Now go find the real cause.

 

[luv2rallye]

If you disconnect the IPS the ECU doesn't know that the throttle is closed and the check for decel fuel cut fails which is what triggers idle surge. The fact it was surging says that the IPS is working.

Steve - question, I'm confused:
If the IPS is misadjusted so that it never closes (electrically) when the throttle is closed, couldn't that also lead to idle surge? (I had a misadjusted IPS and it caused idle problems.)

 

[steve]

The ECU only checks to see if the current idle speed exceeds the thresholds when it sees that the throttle is closed. The IPS is the only way the ECU knows that the throttle is closed so if the IPS never closes it's contacts or if the wire is disconnected the result is the same.

 

[avenged5]

Hmmm.I have a remanned ecu and its done the same thing with 3 different ones so i don't think its that. When i get the chance ll test both the idle switch and the isc. I tried to remove the isc but whoever had the car before me broke off the ends of one of the bolts so just the threads are left in.

 

[avenged5]

Ok Im gonna do a little update because I still haven't found the problem. The ISC is good, ECU is good, O2 sensor is good. Throttle body is clean and valve is functioning properly.


So that being said let me explain the problem a little more in depth. Lets start the car at idle. It is for the most part steady and normal. Then I take off to normal speed and when I push in the clutch and slow down the car surges until I come to a complete stop, and then it stops. So I guess what I have is a rolling surge, not an idle surge. Has anyone else experienced this and know what it could be?

 

[rlacasse1]

I had the same shit happening.

My problem was that it was idling to high and it was causing it to surge from 1500-2000 RPM. So, I did the whole grounding out the little pin on the OBD connector method and I idled the car down to around 850 RPM and the car ran perfect after that. Surge went away completely.

And what you are describing is exactly what my car did, would be ok on start up, but when driving and you it the clutch you get the abnoxious surge.

 

[Boomdeeze]

I had the same shit happening.

My problem was that it was idling to high and it was causing it to surge from 1500-2000 RPM. So, I did the whole grounding out the little pin on the OBD connector method and I idled the car down to around 850 RPM and the car ran perfect after that. Surge went away completely.

And what you are describing is exactly what my car did, would be ok on start up, but when driving and you it the clutch you get the abnoxious surge.

My car does exactly what you are describing and I still can't seem to figure out how to stop it.

 

[avenged5]

I had the same shit happening.

My problem was that it was idling to high and it was causing it to surge from 1500-2000 RPM. So, I did the whole grounding out the little pin on the OBD connector method and I idled the car down to around 850 RPM and the car ran perfect after that. Surge went away completely.

And what you are describing is exactly what my car did, would be ok on start up, but when driving and you it the clutch you get the abnoxious surge.

Ill give it a try when i get home today. The OBD connector is located on the drivers side by the fuse box correct?

And thanks a lot btw!

 

[avenged5]

Eureka its fixed! Apparently I didnt have a BISS, just a plug. Lol. It took me wayyyy too long to figure this out.