Engine/Transmission (1998.5 - 2002) VP-44 Quiz

[csevers]

Does any body know the different parameters that control the timing? Reason I ask is it seems my vp timing is changing a lot(I can hear the change) more than it ever has before and it is not just one change it seems to go back and forth with engine warmed up. I am sure engine load,throttle postion, engine temp make the ecm do its thing but does anybody think fuel temp makes a difference?



Thanks

Craig

 

[HoleshotHolset]

Fuel temp affects timing on the VW's with the VP-37... . not sure on the VP-44's... .



Matt

 

[Amianthus]

From what I've ben told (and could find out on my own), there is a complicated algorithim that determines timing. Several factors determine the timing of the engine, some of which are throttle position, RPM, Engine load (calculated), Air temperature, Manifold pressure, Engine temperature. Based on these conditions, the engine timing will change to produce the most efficient combustion cycle. Mine changes quite frequently also. Especially when it is cold. At a certain RPM, it seems to change timing. My guess is to change from a "warm-up" mode to a "performance" mode. Of course, I could be way off here as this is almost all second-hand.



BTW Craig, I need to borrow your ECM a little longer. The 2000 ECM I tried to blank and re-write with the '99 program, isn't working. Let me know if this is okay.

 

[jtisdale]

WOW, you should have heard my rattle this morning after it started. Big difference with cold fuel. Typically I run (fuel psi) 13 @ idle this morning after sitting for 24 hours and with an ambient air temp or -6° it was running at 10 psi. I do beleive fuel temp has A LOT do do with timing.