GM MEFI Computer / Crate 502 Engine Computer

[dave w]

I'm wondering if anyone has information, links, write ups, or internet form posts about the GM MEFI computer used with a GM Crate 502 engine?

I've found MEFI Scan & Tune, which really stresses the budget. http://www.aldlcable.com/sc/toplevel.asp?cat=32.

I'm hoping to find wiring schematics, and how to pull trouble codes. The engine is up and running, but very poorly. Maybe something is wired wrong, but without schematics I don't know. I'm thinking I need to wire a SES light? I'm trying to figure out how to pull trouble codes, without an expensive scan tool.

Thanks,

dave w

[Buzz]

You didn't mention if this was a friend or a customer ... so some varying options are available.

If it is a friend ... then perhaps a referral ... high-end marina's or custom boat builders often have MEFI tuning software.

If it is a customer ... the easiest course of action for you is to treat this as an 0411 swap (just like with an older Vortec truck). The 502 as the plastic front timing cover - but the CKP hole will be plugged (or solid). Add a 4x CKP reluctor, CKP sensor, a Vortec style distributer, rework the wiring harness, and you are good to go.

The resultant tune will be 100% custom, but if you have a WBO it shouldn't be a problem. If you have a RoadRunner even quicker to do.

[dave w]

You didn't mention if this was a friend or a customer ... so some varying options are available.

If it is a friend ... then perhaps a referral ... high-end marina's or custom boat builders often have MEFI tuning software.

If it is a customer ... the easiest course of action for you is to treat this as an 0411 swap (just like with an older Vortec truck). The 502 as the plastic front timing cover - but the CKP hole will be plugged (or solid). Add a 4x CKP reluctor, CKP sensor, a Vortec style distributer, rework the wiring harness, and you are good to go.

The resultant tune will be 100% custom, but if you have a WBO it shouldn't be a problem. If you have a RoadRunner even quicker to do.

It's potential customer ... I'm wanting to pull trouble codes if possible. If I can't pull codes, I might as well leave with my tail between my legs.

0411 swap seems like a distant option at this point in time.

Thanks,
dave w

[Nasty-Z]

It's potential customer ... I'm wanting to pull trouble codes if possible. If I can't pull codes, I might as well leave with my tail between my legs.

0411 swap seems like a distant option at this point in time.

Thanks,
dave w

Dave ,

I have sent a few emails / texts to some people I know in the Marine field who might / might not deal with this.

If I can come across something I will report back.

TOM

[dave w]

I found this link: http://www.pirate4x4.com/tech/billavista/MEFI/

Has information for Trouble Codes.

dave w

[roughneck427]

Lyndon from westers had mentioned i forgot where on a forum that the interface is the same as the obd1 LT1 i was going to make a crossover connector to use on a mefi aldl setup but the guy never got back to tune it so i never pursued it. I did find some schematics online on some marine forums for the data wire and whatnot on the mefi aldl. I know on efi live forum a guy was building a def file to scan with efilive V4

http://forum.efilive.com/showthread....efinition-file

http://www.marinepowerusa.com/download-delphi-mefi.php