Decarb a Mercruiser 7.4 LX MPI

[Fun Times]

The older EFI Merc big blocks are known to run more on the richer side and having some carbon build up like that under the heads is kind of on the normal side of things.. honestly. Just read some of your spark plugs more closely to help let you know what's going on. Especially since you have a clean start now.

With the older MEFI ECM's both standard and closed cooling systems/ stern drive or MIE engine models used a 160 degree thermostat so there was no ECM adjustments really. The use of a 160 or 170 thermostat and different ECM's for either cooling system really started in 2001/2002 when Merc went to the 555 ECM's.

Maybe I need to go back to school here but a ect is merely a resistor that is heat senstive in this case it resist's based off temp a 5 volt signal is sent in and 3 goes out hence your temp....I cannot see how grounding the housing would be any part of the circuit.

Mercruiser recommends the use of a case ground on most of their sensors. Some info found on posts 33 & 34 might help here.http://forums.iboats.com/forum/engi...a-water-pressure-sensor?p=8856906#post8856906

 

[Fun Times]

Thermostat for yours and mine is part number 807252 2 which does not have rivets.

AD, just to try and help clear things up a bit. Normally the 160 thermostat uses OEM gasket part number 27-530451 and that gasket has the rivets. http://www.mercruiserparts.com/selec..._nbr=802610+98

 

[tpenfield]

Given that I am now winterized, not much else will happen for a while . . .

Knowledge so far is that:

a different ECM not needed & not available
Running slightly rich may not be a problem or may be caused by other factors

Plans are:
Get the exact numbers off the MEFI/ECM units to verify they are as should be
Get MEFIBurn software and run engine diagnostics (Spring time 2015)
Take it from there. . .

I think that I will enjoy seeing the details of the MEFI that the software will show.

 

[Bondo]

Given that I am now winterized, not much else will happen for a while . . .

Knowledge so far is that:

a different ECM not needed & not available
Running slightly rich may not be a problem or may be caused by other factors

Plans are:
Get the exact numbers off the MEFI/ECM units to verify they are as should be
Get MEFIBurn software and run engine diagnostics (Spring time 2015)
Take it from there. . .

I think that I will enjoy seeing the details of the MEFI that the software will show.

Ayuh,...... No doubt 'bout it Ted,.....

 

[Tail_Gunner]

Actually If you get the program tuner pro it will read and display a lot of mefi's function's with one little speed bump...The darling little cabling needed... mefi's female input is rather rare I have never been able to find a cable that will port from the mefi to a common usb computer..a bit frustrating.

http://tunerpro.net/forum/search.php?search_author=cbernhardt

 

[tpenfield]

Actually If you get the program tuner pro it will read and display a lot of mefi's function's with one little speed bump...The darling little cabling needed... mefi's female input is rather rare I have never been able to find a cable that will port from the mefi to a common usb computer..a bit frustrating.

http://tunerpro.net/forum/search.php?search_author=cbernhardt

Yea, the MEFIBurn site references the TunerPro web site. USB cable comes with the MEFIBurn . . . but I guess $595 is quite a price to pay if all you are after is the cable.

 

[Tail_Gunner]

Maybe I need to go back to school here but a ect is merely a resistor that is heat senstive in this case it resist's based off temp a 5 volt signal is sent in and 3 goes out hence your temp....I cannot see how grounding the housing would be any part of the circuit.


Mercruiser recommends the use of a case ground on most of their sensors. Some info found on posts 33 & 34 might help here.http://forums.iboats.com/forum/engin...06#post8856906

[/QUOTE]


tpenfield was good enough to provide a schematic as you can see the element is in complete isolation did i ever tell you i hate electronic's

 

[Tail_Gunner]

Yea, the MEFIBurn site references the TunerPro web site. USB cable comes with the MEFIBurn . . . but I guess $595 is quite a price to pay if all you are after is the cable.

Yes and no...Burn allow's one to reprogram or burn the ecm or better said the eprom and Tuner Pro is a tool graciously given to the public and donation's are expected. for mefi ecm's it is much more of diag tool or allow's one to look at the different parameter's. And is the only game in town for the tinkering crowd mefi burn that is..

 

[tpenfield]

and yet TunerPro does not have an interface cable :noidea:

I'd be happy to make the suggested donation if I could get a cable. then spend the remainder of the $600 on beer.

 

[Tail_Gunner]

and yet TunerPro does not have an interface cable :noidea:

I'd be happy to make the suggested donation if I could get a cable. then spend the remainder of the $600 on beer.

Yes i know...doing a bit af shameless fishing right now one never know's what might pop in from this placed called the cloud....:fish2:

 

[tpenfield]

I found somethings that look like the cable by searching ALDL to USB cables (image search was the quickest). Could the MEFI interface be OBD1 (or 2) cables? :noidea: there are 12 and 16 pin versions . . . thinking it is the 16 pin.

 

[tpenfield]

Looks like it goes back to the OBD Diagnostics (MEFIBurn) site . . . they sell the cable for $60.

 

[alldodge]

I must be missing something because the 12 and 16 pin connectors are for OBD connectors and you don't have one of those on a MEFI-1 or 2

 

[tpenfield]

I must be missing something because the 12 and 16 pin connectors are for OBD connectors and you don't have one of those on a MEFI-1 or 2

Yea, just thinking out loud via the keyboard . . . TunerPro has 'freeware' for analyzing the MEFI, but don't seem to provide any cables to plug into the laptop. Just trying to figure out what cable it is . MEFIBurn provides the cable with the software, but to the tune of $595 . . . So, wondering where I can just get the cable for a small price and use the TunerPro instead of MEFIBurn

 

[alldodge]

Okey Dokey I'm with ya

 

[Tail_Gunner]

http://www.michaelstractors.com/forum/topic.asp?TOPIC_ID=199

That will give you a headache but good stuff for long cold winter night's...and some wine.

 

[tpenfield]

Yea, it is the data link cable connector that you would be after - a 10 pin metri-pack as they refer to it on the link you posted.

 

[tpenfield]

Another option might be to get the MEFIScan version of the software at a price of $195 . . . So, I would get the scan version plus the cable. Since I really don't plan on changing anything in the MEFI program. but if I do . . . There is always TunerPro to look at the more sophisticated stuff.

 

[Tail_Gunner]

Another option might be to get the MEFIScan version of the software at a price of $195 . . . So, I would get the scan version plus the cable. Since I really don't plan on changing anything in the MEFI program. but if I do . . . There is always TunerPro to look at the more sophisticated stuff.

Just buy the cable from obd and use turner pro

 

[tpenfield]

Happy Festivus -

Going through a long weekend marathon of holiday gatherings . . . so just doing a little thread update to hide from the chaos

I am looking at MLK (Jan 17-19 2015) weekend to get a look at the boat (engines) and check the Delphi and Mercruiser part numbers on the MEFI units. In the meantime I color enhanced my Leak Test chart (see below chart on the right side) Green is good, red is bad, Yellow/orange is in the middle. The column '2014' is before the decarb and '2014C' is after the decarb . . .



I figured that 12% or less is good, up to 20% is OK, up to 30% is fair and over 30% is bad . . . So, a bunch of 'red' changed to either yellow or green.

It will be interesting to see/feel how the engines run next season now that the decarb has been done.