Tom_DB1

If I set the (stock chip) FQS switch to reduce timing and add fuel (for whatever reason) does the timing and fuel get changed for closed loop or only open loop? Or does timing change open or closed but fuel only open?

Tom_DB1

Somebody here must understand these switch settings.

Bri Bro

It applies to both. In closed loop, the DME will try and keep the AFR dittering around 14.7/1 but it has a range limit.
http://www.motronic.ws/lambda.htm

Rogue_Ant

Brian is correct.
Additionally, the FQS timing change is only applied >1600rpm.

Tom_DB1

So the seed values are increased or decreased according to the switch position and reducing timing for a NOX issue only works if you can get them to test the 15 mph rolling test in first gear.

Thank you very much.