3.4 dohc wiring and cpu

[craigger13]

Well my project is to put a 3.4 dohc into a 86 sunbird convertable.
I found an engine out of a 95 montecarlo but has no harness or comp.
I was told if i could find a cpu and harness off any other year it would work as long as the harness and cpu matched. Anybody know??

[pepsi_coke]

They are differences in years. 91-93 had a MAP sensor, while 94 went to a MAF sensor. 91-93 were OBDI ECMs, 94-95 were named OBD"1.5" and 96-97 3.4LDOHC had OBDII.

[craigger13]

what was obd 1.5?

[dohcfiend]

also the 91-93 have a different crank sensor/harmonic balancer than the later years. so if you go to a 91-93 ecm/harness put in a map sensor and a 91-93 balancer/crank sensor.
if you go obd2 you will need to put a map sensor in.
obd 1.5 if the ecm setup for the 94-95 dohc engines. it is an obd1 interface with obd2 codes. also the 91-93 uses mpfi(batch fire) and the 94+ uses SFI. just a little food for thought.

[fieromadman]

OBD 1.5 also has the MAF sensor which is better at tuning the fuel trim with a modded engine than the MAP system

[RebelGT]

do a search for the 3.4dohc into J bodies, its been discussed many times here, you're going to run into some major clearance problems if you didn't know that yet.

[craigger13]

Ya i have been measuring and we are gonna do some cuttin weldin and grindin

[SappySE107]

How is maf better for fuel trims? Only with a severely cammed motor (with little vacuum) is the MAP sensor a real bitch to tune. Ive made it work on the pushrod motors before where there was high MAP readings at idle and little resolution, so I don't think I would discount the 91-93 setup for tuning by any means.

If you get the 95 motor, you can run it with any 91-95 setup, so its up to you how you want to go about it. The MAF setup is easier to tune for boost, or with a lot of mods so you can run larger injectors and use the SFI for idle quality. The 95 motor will also have the updated cam/oiling setup that was a TSB on the older motors, so thats a good thing.

If you can find a 94-95 harness and ECM for close to the same money as the 91-93, I would go with it. Also, what transmission are you going to use? If its a 5 speed, then you won't have any trans issues. Otherwise you will probably have some codes for the auto trans as I wouldn't use manual shift logic to get around it for a non E auto trans.