Decarb a Mercruiser 7.4 LX MPI

[alldodge]

Looks real good, you have sure done it up right :thumb:

Maybe get 32 of these (valve seals) and 4 exhaust manifold gaskets and will be in better shape maybe for the rest of the engines years until rebuild
http://www.summitracing.com/parts/slp-st-2004/overview/make/chevrolet

 

[Tail_Gunner]

Your deep enough in this project to measure the resistance in each injector and see how uniform they are and if there is any pattern's to your nicely done table's.

 

[tpenfield]

UPDATE:

OK, the plot thickens

I went to the boat today and got the numbers off of the MEFI units

The Delco Numbers were both the same = 16220371, which equates to an MEFI-1 unit

The other number on the labels are DIFFERENT

Starboard Engine = 860371KA00003804

Port Engine = 860371KA00030814

I checked them 3 times . . . .

The only other number that I could find is a small label on the top edge = "9138" for both units is all that it says.

There was no label on the bottom edge.

The correct Mercruiser part number for these units should be 807268T3, but it seems that the ECM's do not have the Mercruiser number noted anywhere on them. I tried Googling the '860371 . . . " numbers, but nothing came up.

Soooo, I am wondering/thinking that the ECM program may be different between the 2 units, which may have something to do with the starboard engine running rich and the port seemingly better.

Not sure how to cross-reference the 860371KA numbers to the Mercruiser numbers :noidea: Any help in that regard will earn a tip of the hat and hearty handshake

 

[alldodge]

Haven't found anything either, just guessing but think the 860371KA is the Merc BB program tune, and the rest being the serial number count. The 9138 might be the EPROM ID or something similar. When I get my unused stuff back Eddie I can look and see what is on my MEFI 1.

 

[bruceb58]

How hard is it to swap the two on your engines?

 

[Tail_Gunner]

Call mefi burn im sure they will know the calibrtion codes, it would not be out of the ordinary for someone to try a new ecm and run it without knowing it was a the wrong calibration..just another day in the boating world

http://www.mefiburn.com/mefituning.asp

We can tune your controller remotely, anywhere in the world, if you have purchased our MEFIburn[SUP]TM[/SUP] software and you have a high speed internet connection while connected to the vehicle you want tuned. You will be able to watch your laptop's screen as the MEFI calibration parameters are changed and saved. Clear descriptions of what is being done will be explained as it is happening. Our price for remote tuning is $250. Call or email us for details.

 

[Scott Danforth]

^ +1....what he said.

 

[tpenfield]

Yea, I'll be talking with MEFIBurn over the next few weeks to order some 'stuff'. So, I'll see what they have to say.

Just wondering if anyone ha come across reference information to decipher the program specific part number. :noidea:

Not hard at all to switch the units . . . but I'm not sure what that would gain without knowing more about the 2 different ID numbers on them. (typically, that means a different mapping (fuel and timing)

 

[bruceb58]

Not hard at all to switch the units . . . but I'm not sure what that would gain without knowing more about the 2 different ID numbers on them. (typically, that means a different mapping (fuel and timing)

Because of what you said here:

Soooo, I am wondering/thinking that the ECM program may be different between the 2 units, which may have something to do with the starboard engine running rich and the port seemingly better.

 

[bilge rat jim]

Forget about Seafoam- it's pure snake oil. Seafoam contains only 3 ingredients- ISO alcohol, naptha, and light mineral oil, none of which are an active carbon remover. The best carbon removers use polyether amine, a nitrogen based detergent, and the higher the percentage of PEA the better. 2 of the best are Chevron Techron+, and Gumout Regane

 

[tpenfield]

Because of what you said here:

Yea, but I think it would take some time to prove out to see if the port engine builds up carbon rather than the starboard engine, by swapping the ECM's. I'd rather know the correct one up front. So, that is why I would not want to merely swap them.

It seems that the 'program map specific' ID number on the units is a well-guarded secret, as I cannot find any sort of cross-reference listing on the Internet.

 

[tpenfield]

Just to put a visual to the MEFI units and the numbers that I saw, here are a couple of pictures of what I was seeing . . .

PORT




STARBOARD


I was hoping to find the Mercruiser number(s) on them somewhere, but they were nowhere . . . Not sure how Mercruiser keeps track, but there must be some sort of reference list in existence :noidea:

The numbers were pretty similar, in fact at first glance i thought they were the same . . . but on re-check - different.

 

[bruceb58]

That number at the bottom almost looks like a serial number.

 

[Tail_Gunner]

That number at the bottom almost looks like a serial number.

Bingo we have a winner.....those bar codes are the tune programmed into the eprom. This will be intresting to see how it play's out do you have two of the same engine's wtih one matched or mismatched ecu....Or do you have a new engine and a mismatched ecu.....it could be a pleathera or combo's. Now the good new's is you almost have a murder mystery on you hand's and you get to really tinker and with just cause.....

 

[bruceb58]

My bet is the bar codes are not indicating how the ECU is programmed. That's a Delphi sticker. It is put on when the ECU is manufactured with nothing in the memory.

I actually used to work for Delphi/Delco until 1996. Still have many friends who work for them. I could probably find out some info on them.

 

[tpenfield]

My understanding was that the number on the bottom was the program that was loaded to the EPROM, but not 100% sure. If it is in fact a serial number, then there are no markings to indicate the program or Mercruiser part. If you have some sources at Delphi/Delco, that would be great. :thumb:

The only other thing that may indicate the program is the small label that I found on the top edge that says "9138" Supposedly that is a "check sum" on the program file, and if so, then they have the same check sum.

Anyway, just to recap . . .

The engines are both the same (only 3 serial numbers different . . . see signature below)

BOTH ECU's have substantially less hours than the engines and are quite different in their respective hours . . .

PORT = 189 hours on ECU, STBD = 443 Hours on ECU and hour meters at the helm = 740 +/- hours (all at time of engine survey)

So, presumably the ECU's have been replaced or maybe re-programmed during the life of the engines, but at different times.

 

[tpenfield]

Another thought I had was that maybe the "860371KA" is the reference for the programmed unit and the remaining digits are the serial number :noidea:

If that were the case, then the units would presumably be the same, but quite far apart in their serial numbers.

EDIT: of course, I think that I just disproved that theory, as I quickly found a unit in eBay for a 5.7L TBI with the same "860371KA" prefix. It may have more to do with the manufacturer (Mercruiser ) and part vintage than the actual programmed contents.

 

[bruceb58]

the manufacturer (Mercruiser ) and part vintage than the actual programmed contents.

Mercruiser did not manufacture that part. Delphi is the manufacturer.

I believe that exact same MEFI is used by Volvo and others too.

 

[tpenfield]

Mercruiser did not manufacture that part. Delphi is the manufacturer.

I believe that exact same MEFI is used by Volvo and others too.

Yes, I know that . . . Wondering if it is a Delco number that references who the end manufacturer (Mercruiser) is intended to be :noidea: Merely speculation on my part at this point.

It seems that the only marking that would indicate the programmed contents is the checksum . . . Not sure how Mercruiser keeps the parts straight throughout their inventory process, since I do not see any Mercruiser ID numbers on them.

BTW - I visited the Delco/Delphi Plant in Kokomo, IN way back in about 1984 as I was working for one of their suppliers of dash panel displays.

 

[bruceb58]

Been to the Kokomo plant many times. We were actually using ECUs for the project I was working on in California but we were using them for something other than engine control.

The end manufacturer is GM who then sells the complete engines to Mercruiser, Volvo...

When Mercruiser sells these as replacements, they are likely in a Mercruiser box which has their part number on the box. No different than a water pump who is also manufactured by someone other than mercruiser.