Rev hang?

[Funkyflynz]

Hi,

I recently installed a Link CAN Lambda (Link module) and can see that its working, the ECU (G4+) was set to use CLL but didnt have anything connected, anyway i can now see target AFR vs actual and it was off with the engine at normal operating temp, around 12 when idling.

The fuel trim settings for CLL were stock wide band setting, i.e 15% for fuel trim and its maxing out.  I changed the fuel trim limit to 25% and after about 2-3mins saw the AFR's at idle matching the target of 14.7.  25% seems excessive so went back to 15%.  BTW this car have seen a number of track days prior to installing the Lambda sensor and ran like a champ.

Anyways thats a bit of background in hope that it helps diagnose this rev hang issue im now having since installing the Lambda sensor... 

Once up to operating temp (CLL ECT lock is 80deg) the car will idle at 950-1050 nicely, but if i give it a few revs it will come back to 1450ish and hang there for 20-30secs before dropping back to 950-1050.

Any ideas what might be causing this?

Thanks

 

 

[Vaughan]

attach a copy of your basemap and a log of the idle hang please

[Funkyflynz]

E36LS1-log to link.llgHi there,

Ive attached the tune and log from today.  Once the CLL is activated (above 70deg) you can see it is maxing out to 20% trim to try and reach Lambda 1.  In the log you will see that the rev hang gets worse as the car hests up, below 80deg its not really an issue, above 90 is when you see it hang.  At the end of the run i unpluged the Can Lambda to see if that made any difference, this made a huge difference, the car just hung at 1400rpm, it never came back down.

The only other thing i changed was the time to live, it was zero and i changed this to 10sec.  I wouldnt expect this to affect this idles issue though?

Thanks for your help

E36LS1-26-5-20.pclr

Log file attached...

E36LS1-log to link.llg

[Adamw]

For the idle control it appears you are trying drive the valve further than it actually moves.  As far as I know the GM steppers can only move approx 250 steps from fully open to fully closed.  In your log it is up at 415.

So this possibly means your throttle blade is open too far.  I suggest you set your min clamp to about 20, max clamp to about 220, then put it into open loop mode and command the idle valve to about 150, then adjust the throttle stop so that the idle speed is about right at normal warm operating conditions.  Then you will need to redo the base position table during the next cold start before switching back to closed loop.