Using a DOHC ECU to run 3400

[3pointX]

I was told on the GA Owners forum that one of my options to tune my 3400 is to use a DOHC ECU. Apparently there's a bit more support for teh DOHC in terms of tuning compared to the stock ECU in my GA. I'd like to know exactly what is needed to make this work.

Here's what I've got. 1995 Grand AM SE, 3100, automatic. I'm swapping a 2000ish 3400, and possibly a 5-speed if I can source the parts for that swap as well. For now my focus is on the engine. I've been told that I can run the 3400 injectors on teh 3100 ECU but I'll have problems with the fuel mix. On the other hand, the 3100 injectors don't seem like the ideal choice either. And since I can't tune the stock ECU i'm looking for alternatives. I plan on eventually boosting however that's way down the road so I just want to get the most out of it NA.

[SappySE107]

nah, that won't help you any. The 99+ grand am 3400 ECU has more support for OBD2. You have OBD1.5, making it an untunable setp. 94-95 DOHC are MAF and not a drop in solution and not the most supported. Its a different computer than yours so for the hassle, OBD2 is the way to go.

[PCGUY112887]

I wouldn't listen to the people on the GA owners forum... even if you went OBD2 for tuning you would NOT want a DOHC PCM (it's a PCM not ECU) to run it, you would just want a 3400 PCM.

Do you plan on doing anything to the 3400 before it goes in? This will decide your injectors.

[3pointX]

ECU, PCM, call it whatever you want. I really had the intention of doing the swap and calling it a day. I'll fab a new intake and exhaust while I'm at it but that's really just about it until I get the parts together to do the turbo.

[bszopi]

I think he was referring to the swap I had attempted which would have been the 4936 (??) ECM. Yeah, it makes it tunable, but for the price to do it, I'd do an OBD2 swap instead.

[3pointX]

I dunno, some others had suggested that I use the DOHC ECU/PCM/ECM whatever you prefer to call it, and when I asked what needed to be done to make it work, tehy said come here. So here I am. The basic reason I need the tuning capability, or rather want it, is so that I can get the most out of what it's got. I for one know how undertuned engines are from pretty much every car manufacturer, and GM is no exception. I'd much rather be able to run the newer injectors rather than try to get by on the 3100 injectors, plus just having general tuning capability would be ideal. THis is only my second real attempt at doing anything with a car that isn't a Mitsubishi so some of it's a bit foreign.

Now, I've also considered using an SAFC to gain some control over the fuel, as well as a rising rate FPR once I go boost. But the SAFC's from what I've heard do funky, undesireable things to GMs. Then there's Megasquirt. It's a viable option, but not the most ideal for a daily driver IMO. I need a reliable option. Even switching to an EPROM ECU and getting a chip burned if I have to.

[SappySE107]

You need the wiring diagrams for your car, and the one from the donor. The transmission will prefer you go OBD2 as it should be a 4T60-E in your car. I have no idea how the gauges will react though but it shouldn't be different than a 96 grand am 3100. In fact, I would probably try to find a 97 grand am 3100 and go from there.

[montess408]

the newer grand am's came with a 3400 and 4t65-e so why not get everything out of a new car and call it a day ?i know it may cost a little bit more @ the recking yard but it would save you alot of trouble @ home

[Superdave]

Piggyback an OBD1 computer in there...

[IsaacHayes]

Piggy back a megasquirt

[SappySE107]

Grand am did not get a 4T65-E. It got the 45-E, so I would want to keep the 60-E already in there.

[montess408]

oh ! really i did not think that the grand am got the 4t40-45 series trans because of it being a mid size car ?
but yeah i would deff. keep the 4t60-65 series trans

[that_guy]

swap to an obd1 setup. in my 93 gagt with a 3400 5 speed i used the ecm and harness from a 93 3.1 5 speed sunbird, and the dash harness that was originally in the car (Q4 h.o)