GM TBI conversion on a 304 CJ-7

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03-04-2016
Texasdave

GM TBI conversion on a 304 CJ-7

Went to the Junkyard yesterday and pulled what I hope is everything I need to do this conversion. The donor vehicle was 1989 Sierra GMC pickup. The ECM was an 1227747. The BCC is still to be determined. I did not see any where I thought they should be. However on the ECM with all the information it had ASKF. I believe that is the BCC ID. I'll have to check when I get home to confirm the order of the letters. When I did a BIN search those letters did not come up. Anyone know anything about this chip? I will be going through this step by using the information found on this site. The help here has been tremendous especially david w and Eaglemark. I will keep you posted as to my progress from time to time and seek advice. I am putting it on a 304 AMC bored to .30 over. I will check with the fellow that redid it to find the cam he used.
03-07-2016
Texasdave

Okay, basic question. My Jeep did not come with a check engine light so when I'm wiring in the TBI conversion do I need to wire in some sort of light?
03-07-2016
dave w

Yes.

The computer will supply the "Ground" to the check engine light when there is an error. The other wire of the light is connected to the ignition switch ("On").

dave w
03-22-2016
Texasdave

Working on the wiring harness and and I am unsure of which wires I need and which I don't. I have two multi-port plugs in the wiring bundle that connects to the wiring bundle inside the vehicle (1990 Chevy Pick up donor vehicle). DO I cut these out? I think I should but I'm unsure what they connected to inside the cab. I feel like a bomb tech do I cut the pink wire or do I cut the green/black wire. Only good thing, at least I won't blow myself up.
03-22-2016
dave w

Figure out the ECM wiring first, here is a link to the 1227747 wiring schematics: http://www.gearhead-efi.com/Fuel-Inj...Information-42

dave w
03-31-2016
Texasdave

When I removed the wiring harness it had a bulkhead connector, or at least I thought it was. In reality the wires go straight through and are covered by this plastic goop. I heated the goop and it melted allowing me to separate the wires. This makes it easier to work with them. BTW I was careful not to get it so hot that it melted the wire coating.
04-01-2016
fastacton

Quote:

Originally Posted by Texasdave

When I removed the wiring harness it had a bulkhead connector, or at least I thought it was. In reality the wires go straight through and are covered by this plastic goop. I heated the goop and it melted allowing me to separate the wires. This makes it easier to work with them. BTW I was careful not to get it so hot that it melted the wire coating.

Yep, that's the fun part!
04-21-2016
Texasdave

Because I cut the wires short to the ALDL I am going to have to add some wire to be able to mount it. What is the preferred method? Soldering and shrink wrap or unpinning from connector and crimping new wire?
04-21-2016
lakedrifter

hey your in my neck of the woods:)

I'm not at expert at ECMs and programming, but I have worked in wiring a couple years now. When these guys mention re-pinning you usually see it when upgrading to a new style of ECM. They are basically moving the wires around to the corresponding pins for that ECM. Some may re-pin for looks. Some may simply wack and soldier the wires where they need to be. The only time I can see actually having to "re-pin" is if you may some how degrade the quality of the circuit. I know that some wire pairs are twisted and some wires have to be shielded. I'm not sure how I would handle those if I came across one that I needed to cut.

In my case, I'm doing a direct swap. I cut my entire wiring harness from the doner and all my wires are soldiered and shrink wrapped for the ECM.

Heath
05-10-2016
Texasdave

Okay after some thought and consideration of time and quality I am leaning towards buying a pre-made wiring harness. I was talking with a sales person and he voiced concerns about tuning with a performance cam. Something about trouble with the vacuum values changing and the engine wouldn't idle correctly. Couple of questions: 1) Is this really a problem 2) Can you program the ECM to compensate for this anomaly?
05-10-2016
dave w

Quote:

Originally Posted by Texasdave

1) Is this really a problem?

Yes, depending on the camshaft. Usually "Computer" friendly cams are a good option. Computer friendly Does Not mean "Stock Chip" friendly!:mad1:

Quote:

Originally Posted by Texasdave

2) Can you program the ECM to compensate for this anomaly?

Yes, the fuel table (Volumetric Efficiency - VE Table) needs changes based on information from a TunerPro RT data log.

dave w