Very rich idle

[Mn92gvr4]

Got my wideband put in. this video shows my idle. Let me know what you guys think is going on. click and I already check for a boost leak. I'm stumped

 

[number936]

Actually the issue we're trying to track down here is the idle surge (what I'd call a surge anyway, I'm wondering if it isn't what the rest of the DSM community refers to as a hunting idle). To me it seems like the ISC is functioning as it should. It has been pulled apart and cleaned at one point... The issue started after I built the motor ( DSM graveyard Frankenstein rotating assembly with evo 9 pistons, and bumped the compression a bit). This is only warm idle. When its cold it idles fine, if a bit high.


(OP is my brother, I sold him the car)

 

[Mn92gvr4]

Ahh, I see the vid isnt working. Anywho the afr is bouncing between 15-20,rpms between 1300-1700.

 

[tektic]

15-20 afr is lean sir.Also this is quite normal for idle.

Have you set your idle switch, isc, and base timing correctly?

 

[number936]

The BISS wasn't changed since the motor was rebuilt. I will check it for him tomorrow. Does the ISC have to be "zeroed" or something as well?


Idle AFR is fine like you said. It just goes into decel or fuel cutoff (or whatever its called in the DSM tune) until the idle speed drops.

 

[turbohf]

maybe a stupid question, but how do you set the idle switch? (sounds like my car is doing the same)

 

[Mn92gvr4]

Well theres a check mark in the noob box. /ubbthreads/images/graemlins/blush.gif guess I have a full day of troubleshooting tomorrow.

 

[tektic]

the isc is set to 33 at idle while in timing adjust mode with the biss.
The idle position switch is checked for continuity with a volt meter while being operated by hand to make sure it is not keeping the throttle plate open and when slammed shut it should have no resistance (i might have that backwards) check this in both hot and cold conditions.

 

[number936]

Ok, so without the ability to datalog the ISC yet, all I can do is set the base idle to 750 +-50 with the #10 pin on the daig port grounded.

 

[tektic]

If its a vr4 ecu the idle is higher than 750.

850 +/- 100rpm in galants. 750 +/- 100rpm in dsms.

 

[WesternMD_VR4]

heres a good picture guide on how to do a Idle Reset on a 1g

click

 

[Mn92gvr4]

Ok, good news! Idle is at 850 and afr is good. The BISS apearantly had backed itself out over time. Thanks for the help and putting up with my incompetence.

 

[number936]

It was kinda weird, with the car in diagnostic mode or whatever (pin 10 grounded), we threaded the BISS fully closed (like 3 turns) and it fixed the surge and idled steady at 1400rpm. After shutting the car off and starting it again it idled super low and we ended up backing the BISS out a turn or so. Not sure what was causing it to idle high at first with the set screw bottomed out...

 

[tektic]

o-ring may not be sealing as well as it could. After it's set you should cap it. Glad to have been able to help.

 

[ktmrider]

Quoting number936:
It was kinda weird, with the car in diagnostic mode or whatever (pin 10 grounded), we threaded the BISS fully closed (like 3 turns) and it fixed the surge and idled steady at 1400rpm. After shutting the car off and starting it again it idled super low and we ended up backing the BISS out a turn or so. Not sure what was causing it to idle high at first with the set screw bottomed out...

When you ground #10 it sets the ISC at the center of its travel, then you adjust the BISS to get idle "close" so the ISC has plenty of room +/- to adjust for coolant and air temps, AC, etc.

Give the ISC some time to learn the new idle/BISS setting ( it will rather quickly if in good shape ).

Also you checked the resistance of the ISC coils? Make sure it's good else the ECU drivers will fry in a heartbeat.