[Biturbos4] cold running operation on APB

Michael Benno mbenno at yahoo.com
Thu Dec 9 11:50:51 EST 2004

I was hoping some of you more knowledgeable list members could shed some light on the cold running operation for the APB. I am looking to understand what components are involved what settings are modified etc to deal with initial cold startup and how colder air temps affect the system. 

The systems I think are involved include adjustments are to enrichment, timing, and possibly limited boost pressure (not sure boost pressure is regulated on the bypass side or the WG side). I would expect the devices involved would be the coolant temp sender and MAF to determine how cold everything is and how much adjustments are needed. I would assume the ECU deals with enrichment, timing, possibly throttle plate compensation, possibly even boost control. But what other devices are involved and how does it all work.

BTW, I noticed the R$4 has a system to feed additional air into the exhaust on cold running. This is to help the catalytic converters deal with enriched fuel mixture needed for cold running.

Ultimately, I am looking to troubleshoot the cold running conditions in my car. I noticed cold running is getting worse with age. I am getting a kind of cutout on acceleration.


Mike Benno

'00 A6 2.7t 6spd MTM1

Do you Yahoo!?
 Yahoo! Mail - Helps protect you from nasty viruses.

More information about the Biturbos4 mailing list