1G Attempting to set base idle, cars dies when grounding diagnostic pin.

[bigbird94]

I was looking at my logs in ecmlink and my iscposition is in the 68-78 range most of the time at idle. From what I understand it should be at 30. Sometimes my car stalls when the rpms drop down after a pull or even highway driving, I figured this may be why. The ISC was tested and is okay. When I attempted to set base idle, I used link to ground the timing pin and then ground the diagnostic pin, and the car died, tried again, same result.

What should I do? I didn't want to mess with the biss screw without that pin grounded.

This is my DD so any useful responses are welcome.

 

[Kalub]

I've never grounded any pin. Just check your desired RPM in ECULink, and then do the following:

You want ISCPos at or around 30.
Adjust the BISS SLOWLY waiting every few 1/8th turns.
Wait until ISCPos displays the correct readout.

After that the ECU should be able to further correct idle. Also your stalling may, or may not be fixed by this. If it doesn't I would maybe look into calibrating your TPS.

 

[bigbird94]

According to the vfaq page on biss adjustment both pins need to be grounded in order to properly set base timing. Grounding the pins prevents the ECU from controlling idle and sets the ISC in the center of range.

I am not saying you're method won't work, I may even end up tyring it.

The TPS has been calibrated in link.

 

[DSM1G90]

Turn off all of that Link stuff and do it the right and the old fashioned way:

Set base timing by grounding the ECU connection and use a timing light, and reset IAC before doing your BISS screw idle settings.

 

[Kalub]

I've never heard of setting idle with a timing light. I think you misread something.

 

[DSM1G90]

No, but doing base timing first will help get the idle set correctly..what I've always done and what you need to do first before messing with any carburetor/throttle body adjustments...

And done this procedure for many moons now.

 

[WES_393]

For the idle just set your desired idle. Then watch the ISC position while you turn the BISS screw. When the ISC Position is at or close to 30, your done.

The only thing that grounding the pin does is stop the ISC from making adjustments. This way you can get your idle dialed in without knowing the ISC position yet it will still have a full sweep either way.

With Link you know the position, so I see no reason to use the old fashion method. And like Kalub said, that might help with the engine stalling when you ground the pin. The ISC might not be able to keep the idle up when the timing is retarded by grounding the pin.

From the sound of it, your ISC is already maxed out so it wouldn't surprise me if what I described is happening.

Another slight possibility is that the timing is already retarded to the point that grounding the pin retards timing too much to keep the engine running. But that seems unlikely.

 

[Kalub]

No, but doing base timing first will help get the idle set correctly..what I've always done and what you need to do first before messing with any carburetor/throttle body adjustments...

And done this procedure for many moons now.

This is very true, but not really what he was asking for. I was assuming he had the engine timing already set.