Anybody running two ECM's with an enginer swap?

I know that when doing a 3.4 swap to an automatic the engine could run lean. I've heard of running two ecm's for some engine swaps, one for trans and the other for engine. Anybody done this?

Lee

I don't quite understand. If your trans requires the ecm to control it, how could you run it separate? It will still need inputs for all of the engine data.

The only thing I could think of a two ecm application for is if you have a system similar to Holley Projection, that controls the fuel and spark setting seperately. These units are not like our PROM computers though, as they can be flash-burned on the fly and ours require chips.

What need do you have for this? I'm sure there is a better solution out there already!

Bryce
88 GT

I don't know about a separate ECM for the tranny, but my V8 Fiero had and my Quad4 Fiero has two separate ECM's - one for the engine and one for chassis functions.

My Gm product had 2 "ECMs" also but one was for the eng/xmsn/emissions and the other was for the chassis HVAC system.

There was two different "ports" for taking readings with a scan tool to determine the problem. One under the hood, other under the dash.

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Right, I know there are lots of control units for things like ABS, Cruise, HVAC, Traction control, etc...but I don't know of any that have seperate ecm abilities for the trans and engine. I really don't think there is an application where that is the easiest way to do it, but I'd love to hear of a reason to.

Bryce
88 GT

i see the possibilites of some sort of co-phasing but i would be worried of frying both ECMs trying to do so ..

Why would you run 2 ECM's ?

The Fiero Guages, fan, etc. run off the sensors. The cruise has its own module.

The Fuel pump and emissions systems gets wired into the replacement ECM.

OK, The reason I asking this is:

I am building a 3.4 from a camaro into my Fiero automatic transmission. They have a tendency to run lean, and I'm looking or alternatives to pushing more gas out of a fuel pressure regulator.

If there is a way to run the transmission from the Fiero ECM and the Engine from the Camaro Ecm and share information between the two ECM so everybody is happy I would like to investigate such. If not I'll slap a fuel pressure regulator and push more fuel.

Just trying to push that envelope we all love to push.

Why does your tranny need a computer?

TH-125 is hardly an electronically controled auto...

Best!
Ben.

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Ben Cannon
88 Formula, T-top, Metalic Red           "Every Man Dies, not every man really Lives"
88 Formula, Northstar, Silver                     -Mel Gibson, "Braveheart"

There is no reason to run dual ECM's in a Fiero. Period. There are no ECM outputs to the gauges. The speedo is fed from the VSS, not the ECM. There are no "chassis" function that require the stock ECM. There are no fairies. Oswald killed Kennedy, and the aliens next door are actually friendly. Only two Corvette marketing managers failed to overcome their terror of the 2.9L aluminum turbo Fiero prototype and remain under doctors care.

quote Originally posted by terryk: There is no reason to run dual ECM's in a Fiero. Period. There are no ECM outputs to the gauges. The speedo is fed from the VSS, not the ECM. There are no "chassis" function that require the stock ECM. There are no fairies. Oswald killed Kennedy, and the aliens next door are actually friendly. Only two Corvette marketing managers failed to overcome their terror of the 2.9L aluminum turbo Fiero prototype and remain under doctors care.

LOL..thanks Terry...You were getting to what I was avoiding saying myself

Bryce
88 GT

There, I've said and I feel better.

quote Originally posted by terryk: There are no fairies.

WHAT DID YOU DO WITH TINKERBELL?!?!?

Best!
Ben.

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Ben Cannon
88 Formula, T-top, Metalic Red           "Every Man Dies, not every man really Lives"
88 Formula, Northstar, Silver                     -Mel Gibson, "Braveheart"

Where you got the info that auto 3.4 runs lean?? Doesn't make sense to me. And which 3.4 you are talking about? Pushrod or DOHC?

I got the information from other 3.4 pushrod swappers. It makes sense that they would run a little lean. Most put on fuel pressure regulators and run about #48 of fuel with 19 or 24#ph injectors. This pushes enough fuel through the injector to make up for the lean portion. I have talked with another about a custom prom. this is possible, but expensive and many buyers would be needed to counter development.

I would like to know how they measure it. My 3.4 with 2.8 injectors and 43psi never goes close to lean. Other forum member switched to 2.8 injectors and did better. Mine is a 5 speed with a Hypertech stage III prom but I don't think that would make a big difference. Duty cycle is another thing. Just do a LOT of research before you end up buying something you may not need. Just my opinion. Good luck.

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Alex4mula
:) Red-Original Owner & White-1/94 with PM (:

Anybody running a 3.4 auto trans having problems? I did hear this was exclusive to autos only?!

Thanks to all that responded, you have been very helpful, and I'm happy to get that Kennedy thing cleared up.

Lee

I havent heard of anything like that for a 3.4, but in the case of the 3800 series II supercharged v6, running the haltech e6gm ecu with the 4t65e tranny you have to run a stand alone transmission computer system, because the haltech doesnt operate that tranny. The stand alone unit costs upwards of $800, so screw that. I got all my computer problems figured out now though!

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I'm only talking about the Fiero. The ECM only controls the TCC in trans. Any of the other ECM's can do the same thing if you keep the stock 125C. The Fiero ECM does not control any shift points other than TCC lockup MPH and TCC engine load/TPS.

Now the later P4's, etc. I can see where it might be necessary in some cases if the aftermarket ECM can't handle some the functions that factoy ECM's do.