BCAT

I can't seem to find the stuff about changing the air-fuel mix in the DME. Is this worth a try to richen it or get bigger injectors. MAF#4, ARC2

Luke

I dont think It will do you that much good. I'd would bet $5 that you'd need the larger injectors either way.

Russ Murphy

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.

Danno

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.

951and944S

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...?

Danno

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>