SAFC2 Question.

[BLampinen]

this is probably a retarded newbie question, but i'm told that wiring wrong a SAFC2 can result in causing it to be backwards, thus when you try to lean it out some your actually making it richer, and vice versa. the reason i'm asking is because i cannot get my car in tune after 2 months of fiddling with it and no matter what i do, its still spitting black smoke at high rpm's. i'm sure this has come up before, but i'm kinda desperate and in a hurry so i dont have time to search for it right now.
here's what i have Evo3 turbo, 550cc injectors, and 255 walboro. all told, i'm pushing about 25% extra fuel without a controller, right? so i lean out the safc by 25% and it runs like hell and still shoots black smoke. so i lean it out to 30% and the same thing still happens. now i'm sure that having the bigger turbo means that my 25% extra fuel is really not extra at all, since i'm pushing more air now too. is it possible that my safc is backwards or what am i missing? i didnt install it myself, i had a shop do it because they offered to do it so cheap and i was lazy, did they mess it up?
thanks for any input

 

[hystericfox]

The high base pressure from the 255 is probably causing it to run so rich. An adjustable regulator will help it out and make it easier to tune. Also using a wideband or a datalogger will help it, so you can see how rich it's running.

 

[Raph]

a wide band purchase is inevitable, i leaned out 42% to get the good AFRs i have now..

 

[steve]

this is probably a retarded newbie question, but i'm told that wiring wrong a SAFC2 can result in causing it to be backwards, thus when you try to lean it out some your actually making it richer, and vice versa.

No that's not possible. What is possible is to use the wrong wires for a hotwire air metering device rather than the wires for the Karmen MAF or set the SAFC to the wrong type metering but those won't cause it the reverse the operation of the SAFC just cause it not to work and usually to throw a CEL for the MAF.

Steve

 

[BLampinen]

ok, here's my next question: last time i raced i was boosting 24psi on 96 octane fuel(made by mixing toulene and 92 octane pump gas) at that pressure, my safc was reading ~2400Hz Karmen, and i had no timing control so i left that up to the stock ECU, but i wasnt reading any knock on datalogger or safc. now, with this setup i was tuned out to -15% from 0-3000rpm and -30% from 3200-7500rpm at Hi-Throttle (50%+).. with this, i ran my fastest time yet (13.9 @ 104) compared to 14.7 @ 99 un-tuned. but again, i was shooting black smoke above 5000rpm, so i'm still running rich and still think i can get more out of my car at the track. now, whenever i tried to lean out my low-rpm range below -20%, the car wouldnt rev above 2800rpm. is it possible that somehow i'm running really lean at low rpm and really rich at high rpm, despite my tuning settings?

now, i know for sure that the safc was wired to read Karmen reading, cuz the installer was telling me about Karmen and he owned a DSM himself, and he was trying to sell me on a GM MAS/MAFT but i didnt have the money. also, i intend to buy a wideband and datalogger as soon as i get my current problems fixed... since writing the first post and this one, i managed to get hit by a moron running a stop sign and now my car has serious front-end damage, plus my suspension is toast so i need to buy new suspension all around.

also, for the first 2-3 weeks, my ECU kept throwing a CEL for an interruption in the MAS circuit. after those couple weeks, tho, it went away and hasnt come back. so i dunno about that one.