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Thread: Recommend a GM ECM/PCM for custom application.

  1. #1
    Potential Tuner
    Join Date
    Jun 2009
    Posts
    9

    Recommend a GM ECM/PCM for custom application.

    I need some help deciding which GM ECM to use to run a non-GM engine in a street rod. The engine is a BMW 5.0L V12 mated to a Getrag 262 6 speed manual. It has two distributors, each running one bank of six cylinders. It has a 58x crank trigger wheel with a separate sensor for each bank. BMW used two Motonic ECMs to run the engine as two inline sixes, I plan to do the same thing with two GM ECMs. First and foremost I need an ECM/OS that is well supported, must be able to disable VATS and be functional without a BCM/TCM, etc.. I would love to use the existing 58x crank reluctor, but I can change it if necessary. There are no cam sensors on the engine, they used inductive pickups on two plug wires. There is plenty of room inside the distributors to add whatever is necessary. I'm not opposed to switching to DIS or COP and it is probably preferable, new caps rotors and wires for this engine are about $700 aftermarket. I prefer to run speed density, I am more familiar with the tuning process and don't really have room under the hood for MAFs. I will need to replace the throttle bodies, I can go cable or wire. DBW would be a big advantage since it would be somewhat difficult to connect and sync two cable driven throttles on opposite sides of the engine. The newer smaller ECMs would be preferred due to easier mounting and lack of room to fit them in the car, especially since I'll be needing two of them.

    I've been considering the 2008+ Silverado E37 4.3 V6, it seems like the best match but I'm concerned about it not being well supported. I looked at a 2010 Silverado 4.3 from the repository and there are only two DTCs listed. I'm sure I'll need to disable a lot more than that. I'm not confident that I can get that working as a standalone ECM. My other consideration is the 12200411 with ~2001 4.3 V6 truck OS. This seems very well supported with factory manual trans option, but does not offer some of the advantages of the newer ECM.

    If you have any recommendations or see something I missed, please let me know. I've got plenty of time to get this going, but I don't want to be wasting money on a bunch of parts and credits that won't work. I'm assuming I cannot just use a V8 OS on a 6 cylinder by changing the cylinder select to 6, correct?

  2. #2
    Tuner JnJSpdShop's Avatar
    Join Date
    Aug 2005
    Location
    Western New York
    Posts
    195
    I would check with Holley EFI. I know the Dominator EFI system will run 2 DBW TBs. You would certainly have to switch this engine to coil near plug ignition

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  3. #3
    Potential Tuner
    Join Date
    Jun 2009
    Posts
    9
    I've used several different aftermarket controllers including a Holley Commander 950 that had to be sent back twice to repair hardware failures. I'd rather stick with a cheap and reliable GM ECM if one exists that can be made to work.

    I found an 08 GMC 4.3 file in the repository and it looks better than the '10 I looked at previously, but then I discovered the new VE calculation methods GM is using, I'm not sure I want to get into that mess.