GM TBI on Jeep 4.0 Engine in AMC Eagle

[Baskinator]

Hi all,

I'm new to the forum, searching for info regarding the GM TBI from a 4.3 V6. I have an AMC Eagle that is my daily driver and I've wanted to fuel inject it for the longest time. I initially looked into the Mopar/Jeep fuel injection, but it's a lot of extra work and way more expensive for the kit. I couldn't justify the cost in fuel savings and I can't have too much down time for installation.

I have a junkyard wiring harness, tbi, air cleaner, and two computers from an early 90's Chevy Astro van. I was thinking of doing an entire junkyard install, but I have some questions I was hoping some of you might be able to answer.

My biggest question is about spark control or a "fuel only" conversion. The car has a Duraspark distributor that could be wired up with an 8-pin GM ignition module, but if it's viable I would prefer to have fuel control only (at least at first). Can a "fuel only" conversion be done using an unmodified, stock computer so I can continue using my MSD CDI ignition? Will it run reasonably well without spark control? I do not have access to chip burning hardware, nor do I have the expenses to spare. I'd like to be able to plug and play if a computer were to die on me for some reason.

Also, the Astro van my junkyard parts came from had trans control wiring. Will that pose a problem, or can the wires just be removed?

Thanks in advance for any help you can give!:happy:

[blue68deville]

I can tell you that if you can wire your distributor to the 8-pin module, then you can probably use the MSD box too. I did that with my Caddy, used an MSD dist to trigger the GM module for ECU controlled timing and had the 6A box & MSD coil provide the spark.

I'd have to look at my wiring diagrams to remember exactly how I included the 6A. IIRC the trigger for it is just the neg side of the coil, comes from the ign module pin C

Halfway down the page: http://www.megamanual.com/ms2/GM_7pinHEI.htm

You want the ECU to control timing, it works WAY better.

[Baskinator]

Interesting, I didn't know you could wire the MSD up using the GM module as well. I thought it was either one or the other. I'd be very interested if you could remember exactly how it was done.

I guess it wouldn't be too bad to set it up with timing control. My main concern is how to actually mount the GM module where it will stay cool and waterproof. I had a 4-pin GM module wired to the Duraspark dist earlier this past summer. It ran great (attached to metal with heatsink paste), but unfortunately it got wet and left me on the side of the road. Luckily there was a spare in my glovebox.

I'm really looking for reliability here, so I'd like to build it as well as possible.

[Baskinator]

BTW, halfway down this page is how I would wire the Duraspark:
http://tc.wagoneer.org/2012/08/gm-tbi-ignition-wiring.html

[blue68deville]

That link looks like the way I wired mine, except I have pin C going to the trigger of the 6A, same wire you would use with points. Then the box powers & fires the coil.

I haven't had any problems with water, but the caddy is more of a fair weather ride. The 7-pin module looks fairly well sealed, I've seen some TBI distributors that were pretty damp and still running.

Have you checked into a TBI/TPI conversion dist for the 4.0? I swear I've seen them. That would be easy, and no playing with rotor phasing when you lock out the duraspark either.

No ECU will be happy with the timing not hooked up.

You will probably want an older ECU like a 1227747, no trans control. The newer ones don't like having no trans input/output signals, but that can be tuned out.

You can repin the harness you have to work with the older ECUs, and trim off the locator lugs on the plugs to plug into the older style module. That's what I did, my TBI and harness is a 93 and the ECU is a 7747.

I'm sure someone on here has done this conversion and will have more info. I've only done 2 conversions, a Chevy 454 and the Caddy.

[Baskinator]

Is it possible to tune the chips without burning/erasing them?

[blue68deville]

Check the vendor section, there's a few folks that provide tuning services based on what your setup is.
You can also do your own, it's not that hard. Especially if you have a vendor set you up with a starter chip.