Can't get ISC in range

[Chicken Patty]

hello,

I can't get my ISC in range to save my life. My idle is fine at about 850 which is what it's set at in link, but when I am idling and the vehicle is moving (coming to a stop light) the idle is super high, close to 2k, then when I stop it comes down to 850. I know the value in Link should be 30, but on idle I'm at over 70 and my idle is already down to 750. If I open my BISS more to lower the value the cars idle drops really low. So I don't know what the hell I'm doing wrong.

Is there a certain procedure for this? What I usually do is:

Ground diagnostics connector, I have my Target idle at 750 in link, then I try to set it to 750 while grounded. Once its around there, I un-ground the diag. connector but at that point the ISC way over 30, so I don't know if I'm overlooking something or what.

Any help?

 

[livedsm4g63]

When was the last time you checked your base timing?

 

[agentorange313]

When I emailed Thomas Dorris about setting the idle in my car by adjusting the biss screw so the iac can be properly adjusted, he told me that the connector for the ECMlink will ground everything needed. The process of using an alligator clips to ground the connectors is not needed.

"ECMLink just provides a way to "ground" those pins (either the diag port pin or the base ignition timing pin) using your laptop rather than physically doing it yourself. Everything else about the procedure stays the same as outlined in the shop manual.

Honestly, the easiest way is to ignore all that grounding crap.

Just put your desired idle speed into the RPM tab and then datalog "ISCPosition" in ECMLink. Adjust the BISS until ISC position is "around" 30 or so."

-Thomas Dorris (taken form an e-mail to me).

I would check for boost leaks/vacuum leaks in the car. Correct me if I am wrong but the GM MAF and mitsu MAS function on the same principle, so boost leaks will effect the a/f ratio.

I had the same problem and needed to change my injector seals.

 

[LTUDSM]

As agentorange313 said. Make sure,that the engine is at operating temp. 196 and up. Turn the biss (clockwise or counterclockwise) wait 3-4 mins and then check the ISCPosition value..... It takes time for ISC to learn the idle each time you turn the BISS screw......

 

[Chicken Patty]

When I emailed Thomas Dorris about setting the idle in my car by adjusting the biss screw so the iac can be properly adjusted, he told me that the connector for the ECMlink will ground everything needed. The process of using an alligator clips to ground the connectors is not needed.

"ECMLink just provides a way to "ground" those pins (either the diag port pin or the base ignition timing pin) using your laptop rather than physically doing it yourself. Everything else about the procedure stays the same as outlined in the shop manual.

Honestly, the easiest way is to ignore all that grounding crap.

Just put your desired idle speed into the RPM tab and then datalog "ISCPosition" in ECMLink. Adjust the BISS until ISC position is "around" 30 or so."

-Thomas Dorris (taken form an e-mail to me).

I would check for boost leaks/vacuum leaks in the car. Correct me if I am wrong but the GM MAF and mitsu MAS function on the same principle, so boost leaks will effect the a/f ratio.

I had the same problem and needed to change my injector seals.

As agentorange313 said. Make sure,that the engine is at operating temp. 196 and up. Turn the biss (clockwise or counterclockwise) wait 3-4 mins and then check the ISCPosition value..... It takes time for ISC to learn the idle each time you turn the BISS screw......

When was the last time you checked your base timing?

Car has not leaks, I have boost leak tested it recently and checked base timing. Those things are all fine. Only thing I can think off is I'm not being patient enough, or ISC is going bad, but I have yet to test it.

I have one questions though, whether your target idle is 750 or 900 RPM's, is the value you are shooting for still 30 or so on the log?

 

[agentorange313]

yea the value should still be 30 at any idle.

Just put your desired idle speed into the RPM tab and then datalog "ISCPosition" in ECMLink. Adjust the BISS until ISC position is "around" 30 or so.

testing ISC (IAC):
http://www.dsmtuners.com/forums/articles-tuning-ecu/386663-dsm-isc-motor-testing-replacement.html

 

[TurboAnything]

The problem could be in the tuning improper maf comp settings for example. Also have you considered that one of the coils is bad in the ISC? I would use a multimeter and OHM out the pins on the ISC and make sure it is good.

 

[Chicken Patty]

The problem could be in the tuning improper maf comp settings for example. Also have you considered that one of the coils is bad in the ISC? I would use a multimeter and OHM out the pins on the ISC and make sure it is good.

As far as tuning, I would doubt that, since I have been tuning my car for a long time now and I had never had this issue till recently. So, I'll def. check things out again, but seems to me more like a bad ISC. I'll get around to adjusting it one more time, if not I'm testing it or maybe see if someone has one i can try out that I know is good.

 

[agentorange313]

if you gotta replace it, here is where I got mine:DSMISC Automotive (New ISC Supplier)

or I am sure you can find one in the classified ads, but dsmisc.com is the lowest price I have seen ever for an ISC.

 

[Chicken Patty]

if you gotta replace it, here is where I got mine:DSMISC Automotive (New ISC Supplier)

or I am sure you can find one in the classified ads, but dsmisc.com is the lowest price I have seen ever for an ISC.

Damn, that's a good price for an OEM unit. I was thinking of picking up a BW unit from Autozone and trying that out, my buddy works there so he'll let me return it if it don't work good, but for this price I rather just get a OEM unit. Thanks bro.

 

[davidalindsey]

Was it doing this?
rpm rises in neutral then slowly goes down

 

[Chicken Patty]

Was it doing this?
rpm rises in neutral then slowly goes down

That is exactly what my car is doing! Did you ever fix that?


EDIT: I just messed with it a bit, my ISC has to be shot, sometimes I adjust the BISS, idle starts to climb but ISC value doesn't change. So I just gave it about 2.5 turns out from fully closed and car is behaving better, not great, but much better. At least like this it's not idling high as hell before coming to a stop or on start up. However, my ISC value is over 70 like this so obviously something is wrong. Next, I'm definitely going to test it.

 

[davidalindsey]

I installed an old ISC that I had laying around and that seem to fix it.
The one in the car, the ISC would not rotate fully. The new one I put it rotates more than the old one.
I'm sure you just need a new ISC.
I am glad I got mine fixed, it was so aggravating.
Here are some helpful links
Welcome to my Idle Speed Control (ISC) Test/fix page
DSMISC
DSM ISC motor testing & ReplacementDSM ISC

 

[Chicken Patty]

I installed an old ISC that I had laying around and that seem to fix it.
The one in the car, the ISC would not rotate fully. The new one I put it rotates more than the old one.
I'm sure you just need a new ISC.
I am glad I got mine fixed, it was so aggravating.
Here are some helpful links
Welcome to my Idle Speed Control (ISC) Test/fix page
DSMISC
DSM ISC motor testing & ReplacementDSM ISC

Thanks a lot for the reply bro, I'm still going to go test mine and then I'll go from there. But I'll def. be keeping an eye out for a ISC.

 

[92AWDTalonTSI]

I was told that the car will hold idle up when moving but then slowly go back down after stopped.

 

[Chicken Patty]

I was told that the car will hold idle up when moving but then slowly go back down after stopped.

Yeah, but not at 1700 rpm's.

 

[davidalindsey]

You dont happen to have the AC switch on while this is happening?
I just noticed mine only does it when i have the AC switch on to fun the fan.

 

[Chicken Patty]

You dont happen to have the AC switch on while this is happening?
I just noticed mine only does it when i have the AC switch on to fun the fan.

I have a ISC on the way now, but I borrowed my buddies in the meantime since his car is about a week or two away from running again. I got it dialed in perfect, 30 on idle and the learnidleadjust is 141 or so. The car even with the a/c on while moving idles at about 1200, then slowly comes down to 900 which is my target idle as I get closer to zero.