5.0 to 5.7 swap

[greengmc]

I am swapping a 5 liter out of a 94 GMC 4x4 with a 1990 5.7 from a suburban 2x4. Will my ECM work? I do have an overdrive tranny as well as the other truck. Any input would be great! Dean.

[Chris_Harper]

I just did the same basic swap, from a '90 305 to a '95 350. I got the ECM in my sig for mine. I went to my local u-pull-it yard and got it from a '92 G20 van- under the driver's seat on them. It will run on the 305 ECM, just not the best. See what you can get one local at a yard for. I paid $40 for mine. Best thing is to get a custom chip done. I will do that later on, when I put in a better cam. Being 4x4 vs 2x4 I don't know what that will do.

[Levi18]

I'm still running the 305 ECM in mine because for some reason the 350 one wouldn't work. So far I haven't had major problems, except that it isn't running as well as it could.

Also, in the van I bought, the ECM was in the pillar beside the drivers seat.

[greengmc]

Well I got mine started this evening but seems to be overfueling...rich exhaust! Does anyone know of any websites to help in matching ecm's?

[Chris_Harper]

http://www.tbichips.com has a good list. Or at least it says what came in what. Should be able to match one up that way.
The one in my sig supposedly has the best tuning from the factory. I don't know if it will be plug and play for your truck. It was for my '90.

[whitelightnin92]

in 94 they changed the connectors, so a 6299 wouldnt work. he should keep the current ecm and find a chip for it

[greengmc]

Well it's running fantastic now!No ecm change at all. We did however were very patient when doing the timing. Perfect timing I believe is the key! Thanks all.

[bwood]

I was thinking that the tranny in a 90 was a 700R4 with only a electronically controlled OD and the 93 should have a 4L60E which changes all gears electronically. The ECM's should be different in this respect. It might be possible that the 93 has the 700R4 so I guess it would work.