Can I eliminate the MCU completely?

[edons]

I just got my new engine running in my CJ7 . But i couldn't get a spark forever and it turned out to be the MCU. So, I performed a nutter bypass to eliminate the MCU for ignition. Is there any way to eliminate the MCU completely for everything?

 

[Busted Knuckles]

Im not sure your can ask that question, or not sure if it can be legally answered.

There are some legalities involved with that question, its not a cut and dried answer, or at least the answer would pertain to off road use only. Not sure what the rules on this forum are in that regard, so I will refrain form answering it.

Somebody else may jump on it, but Ive got to leave it there.

If nobody gives you a reply, pm me for discussion.

 

[CJ]

Answer away... This is a discussion forum. Members are responsible for thier own aplicable laws.

 

[Busted Knuckles]

Thanks Cj, Yes, you can do away with the MCU, youd want to change out the carb and the distributor if youd like to to run "well", you would be pleasantly surprised with the additional power and driveability.

Im assuming you dont have vehicle inspections where you live, because if you did, you might run into problems there.

If you decide to do away with the MCU, search this site for HEI Distributor, and may I suggest the Motorcraft 2100 carburetor. Your other popular option is the Weber carb, you should find plenty of reading on both, as well you have more than one choice for a replacement distributor.

 

[BusaDave9]

The nutter bypass isn't enough to eliminate the MCU. As Busted Knuckles said you would need an HEI ignition before you can get rid of the MCU.

 

[Jimbos76cj]

Is he talking MCU.. the computer or ignition module? I did the nutter bypass, swapped on a 2100 and left the ignition module and it fired right up. once i get some cash back in the jeep fund ill be grabbing an HEI and pulling the ignition module.

 

[edons]

Thanks Cj, Yes, you can do away with the MCU, youd want to change out the carb and the distributor if youd like to to run "well", you would be pleasantly surprised with the additional power and driveability.

Im assuming you dont have vehicle inspections where you live, because if you did, you might run into problems there.

If you decide to do away with the MCU, search this site for HEI Distributor, and may I suggest the Motorcraft 2100 carburetor. Your other popular option is the Weber carb, you should find plenty of reading on both, as well you have more than one choice for a replacement distributor.

Sorry I wasn't replying for a while. I went on vacation where there was no internet. There are no vehicle inspections in ohio, so I don't need to worry about that (it would never pass, even with an MCU). I already changed out the carb so its now a Weber carb. distributer i believe is original. What about gauges that use the MCU?

 

[Jimbos76cj]

If you want to remove the ignition module you will need to swap out the distributor. then the only wire needed for the engine to run besides the one that goes to the started selenoid will be the 12v that goes to the HEI.

you should beable to run the ignition module with the weber with no problem also. the gauges dont run off the ignition module with except maybe the tach if you have one. IF you have a tach and change out to a HEI theres a tach hook up on the cap.

 

[Busted Knuckles]

If you want to remove the ignition module you will need to swap out the distributor. then the only wire needed for the engine to run besides the one that goes to the started selenoid will be the 12v that goes to the HEI.

you should beable to run the ignition module with the weber with no problem also. the gauges dont run off the ignition module with except maybe the tach if you have one. IF you have a tach and change out to a HEI theres a tach hook up on the cap.

What he said !

 

[ken98k]

What's an MCU?

 

[BusaDave9]

What's an MCU?

It's the Main Control Unit mounted on the fender in the engine compartment.

​

Also edons I have to say I don't like your signature. No offence but I just don't like those long words. I don't know why. I googled it and found out it should be spelled Hippopotomonstrosesquippedaliophobia not Hippopotomonstrosusquipedliophobia. It's a minor spelling mistake. Don't take it personally. I sure hope you don't have scriptophobia or we may never hear from you again.

 

[Jimbos76cj]

Ahhh I've never heard it called MCU.. Normally I hear ignition control module. Figured MCU was the "computer" they stuck in the CJ's

 

[Busted Knuckles]

What's an MCU?

MCU, Master Control Unit, same as an ECM, ECU, Brain, Controller, Computer, PCM..Used on the Cj in 1984, 1985, 1986.


The image BusaDave posted is an ignition control module of the Motorcraft Design, regardless of whos name is on it. .

I think what BusaDave meant to show you:

 

[Jimbos76cj]

Nutter bypass will take care of the MCU or the computer.. HEI will get rid of the ignition module.

 

[edons]

I took out the computer and the thing runs perfectly. no mods or anything just removing the computer.

 

[edons]

It's the Main Control Unit mounted on the fender in the engine compartment.

​

Also edons I have to say I don't like your signature. No offence but I just don't like those long words. I don't know why. I googled it and found out it should be spelled Hippopotomonstrosesquippedaliophobia not Hippopotomonstrosusquipedliophobia. It's a minor spelling mistake. Don't take it personally. I sure hope you don't have scriptophobia or we may never hear from you again.

I was actually tailing about the computer under the dash. the factory manual refers to it as an MCU (motor control unit). What you showed is referred to as an ICM (ignition control module). thats just what the manual says.

 

[edons]

It's the Main Control Unit mounted on the fender in the engine compartment.

​

Also edons I have to say I don't like your signature. No offence but I just don't like those long words. I don't know why. I googled it and found out it should be spelled Hippopotomonstrosesquippedaliophobia not Hippopotomonstrosusquipedliophobia. It's a minor spelling mistake. Don't take it personally. I sure hope you don't have scriptophobia or we may never hear from you again.

I was actually talking about the computer under the dash. the factory manual refers to it as an MCU (motor control unit). What you showed is referred to as an ICM (ignition control module). thats just what the manual says.

 

[1986cj7]

I was actually talking about the computer under the dash. the factory manual refers to it as an MCU (motor control unit). What you showed is referred to as an ICM (ignition control module). thats just what the manual says.

Just noticed that in your info box top left you have down i6 2.5l I6 is a AMC 258 i6 / 4.2l or a 4.0l are you sure you don't have a I4 GM 151 or what ever the displacement is. :dunno::dunno:

 

[edons]

Just noticed that in your info box top left you have down i6 2.5l I6 is a AMC 258 i6 / 4.2l or a 4.0l are you sure you don't have a I4 GM 151 or what ever the displacement is. :dunno::dunno:

wow i didn't even realize that. i have an I6 AMC 258 i6 / 4.2l , it used to be an I4 2.5L. i must have forgot to change it or something..