How to convert to Pre-94 OBD I ???

[TheDirtyBen]

does it really matter if the DOHC code gets decoded since i have 3100SFI? I'm a little confused. If i run 94/95 DOHC ECM along with matching MAF, then i don't need to get a 3.1MPFI chip?
basically, can the 3.4 DOHC chip and ECM be reprogrammed to tune the 3100SFI?

[blackbombshell95]

hmm. good question. and how much tuning could be done? probably better on going to obd 1.0

[SappySE107]

Ive tuned 3 gen 3 pushrods now using MAP and MPFI. The 91-93 DOHC code and all 3.1 codes are much more detailed in their code definitions, so I wouldn't really try to use a 94-95 DOHC code right now for anything other than a 94-95 DOHC.

[TurboGTU]

91-93 w-body with an 3.4 DOHC automatic. All the harness and PCM ('396). You would prob need to adapt some wires for the trans..as I don't know if the plugs change. ALso ..thise would eliminate SFI...since older TDC were PFI. SFI is useless beyond part throttle anyway. You would need to use the TDC injectors. As far as running..it will run...onece it goes into close loop it will adjust a little to compinsate for the difference in fuel requirements. ON the dash gueage and ALDL port...you need to wire it and pin it to the PCM. When you tune the PCM..you can recalibrate your speedo,tach. You can always go to aftermaket gueages...but you would still need to pin the ALDL port since you want to log what the PCM is doing.

YOu would need the wire schematics from both cars. This by all means is not a weekend task. YOu can say your installing a Holly Commander EFI ECM...but with trans controll.

[SappySE107]

Actually, i think the stock 00+ gen 3 injectors will run as well without changing the code. He is just down the road from me so tuning shouldn't really be an issue for him once the ALDL is wired up and the OBD1 connector in place.

[TheDirtyBen]

ok, so now i'm totally lost! PLEASE refer to the very first post. one minute i'm being told to get 94/95 DOHC ECM and MAF, another minute i'm being told DOHC ECM with 3.1 MPFI prom, and another minute someone says 91-93 DOHC Auto.
My car is 94 3100SFI/4T60-E.
I just want the easiest and least expensive route to tuneability. I honestly don't know the difference between MPFI and SFI other than MPFI has one injector ground terminal @ the ECM and i believe SFI has two.

[TheDirtyBen]

BTW, i have the OBDI connector factory installed. UGH.....I have to goto Russ Moore Transmission anytime i need codes scanned. Thankfully i don't get any since the engine swap.

[SappySE107]

another minute? Try another year.

You want the 4T60E based computer, from a 93 3.1 W body or the 91-93 DOHC.

[TheDirtyBen]

ok, i'll remember 93 w-body 3.1 or 3.4.