DME Adjustment
#3
There is an old thread with a link to the correct DME info. However, it won't help if the issue is leaning out at higher boost/rpm levels. The switch basically (I believe) increases the duty cycle across the board and if you're already at 100% duty cycle you can't go any higher. Somebody like Danno could tell you for sure, but I believe this is the case.
#4
Race Director
Yeah, I suspect that enriching the mixture with the DME may actually CAUSE high-end leanness. You're stealing duty-cycle from the high-end to fatten up your mid-range, but as the RPMs get higher, the point where your injectors reach 100% duty-cycle will be EARLIER than before.
I'd have to hook up a 'scope to the injectors to really be sure though. But I really don't think there's any free lunches to be had here.
I'd have to hook up a 'scope to the injectors to really be sure though. But I really don't think there's any free lunches to be had here.
#5
Race Car
The mods listed should be OK with stock injectors, unless they are operating in "less than perfect" condition....?
Isn't fuel enrichment, with the DME also accompanied by a certain degree (pun intended) of timing retard...?
Isn't fuel enrichment, with the DME also accompanied by a certain degree (pun intended) of timing retard...?
#6
Race Director
Well yes and no to the ignition. You actually have 7 possibilities as far as combinations of fuel-enrichment and ignition retard. There's a table here:<a href="http://www.bonnevillemotorwerks.com/fqs.html" target="_blank">Fuel Quality Switch settings</a>
Ignore the part where they mention "early motronic"; I think they're referring to pre-'90 DMEs. The settings shown at the bottom is for the '85.5+ 944NA and '86+ 951. For settings for the truly early 944NA pre-'85.5, check out F.R. Wilk's <a href="http://members.tripod.com/early944/" target="_blank">Early Edition 944 website</a>
Ignore the part where they mention "early motronic"; I think they're referring to pre-'90 DMEs. The settings shown at the bottom is for the '85.5+ 944NA and '86+ 951. For settings for the truly early 944NA pre-'85.5, check out F.R. Wilk's <a href="http://members.tripod.com/early944/" target="_blank">Early Edition 944 website</a>