Mercruiser 350 mag MIE ECM

[tluns]

Boat died today after running for two hours. I was running about 2800 went to throttle down and it just throttled down to dead. Turns over but no spark. Power is good to coil and ignition module. Also swapped out with a known working coil and module. Distributer turns and cap/rotor were ok. A couple weeks ago it ran poorly above 2000 we thought maybe an injector issue but it went away. Today the RPMs were moving up and down a bit under throttle. Mechanic believes it is the ECM. Any thoughts? Is there a way to troubleshoot the ECM? Motor is repowered 2011 mercruiser 350mag mei horizon. 115hrs.

 

[Fun Times]

If possible, could you post a photo of your ECM design & distributor assembly to help get a better idea of your working system design?

Being an remanufactured engine of 2011, There were a few variance of design models and the engine serial number may or may not work in this case but if you could post the serial # too it might help some too.

 

[tluns]

Boat died today after running for two hours. I was running about 2800 went to throttle down and it just throttled down to dead. Turns over but no spark. Power is good to coil and ignition module. Also swapped out with a known working coil and module. Distributer turns and cap/rotor were ok. A couple weeks ago it ran poorly above 2000 we thought maybe an injector issue but it went away. Today the RPMs were moving up and down a bit under throttle. Mechanic believes it is the ECM. Any thoughts? Is there a way to troubleshoot the ECM? Motor is repowered 2011 mercruiser 350mag mei horizon. 115hrs.

 

[alldodge]

Don't see the ECM being the issue right now

As FT mentioned, need to know what you have? Repowering in 2011 could be a few different models. If your motor uses the flat distributor cap, I would recommend replacing it because these caps can go bad without warning and look great. If its not the cap then its still good to keep it onboard for when it does go out

 

[QBhoy]

Doubt it. Much much more likely it’s the famous Diz cap mpi issue. Heard so many times now that the cap “looked ok”...Just buy another one and see what happens. Good chance you’ll be smiling afterwards

 

[Scott06]

Take the coil wire off the ditributor gorund it and crank it over to see if you have spark to the cap. If you do you know its cap rotor or some how getting grounded inside the ditrbutor.

 

[tluns]

Took awhile to get back. It is a 350mag mpi horizon fwc. It is the flat cap distributor. Coil ignition module mounted on a plate next to distributor. The engine is running again. Diagnostics showed no codes and all run tests were sat while it was dead. After it restarted it died once about 10 minutes in , restarted a few minutes later and runs strong. Have about three hours on it and couldn’t make it die. Have sent ECM to company in San Diego for a $50 function check. Their opinion on hearing all the details was possibly moisture in the ECM or a bad harness/connection. I am leaning towards connection but thought $50 was cheap reassurance on ECM.

 

[tluns]

Took awhile to get back. It is a 350mag mpi horizon fwc. It is the flat cap distributor. Coil ignition module mounted on a plate next to distributor. The engine is running again. Diagnostics showed no codes and all run tests were sat while it was dead. After it restarted it died once about 10 minutes in , restarted a few minutes later and runs strong. Have about three hours on it and couldn’t make it die. Have sent ECM to company in San Diego for a $50 function check. Their opinion on hearing all the details was possibly moisture in the ECM or a bad harness/connection. I am leaning towards connection but thought $50 was cheap reassurance on ECM.

Also, when it failed there was no spark at coil or plugs and the diagnostic check showed module, coil, rrr egg lays behaving properly.

 

[tluns]

Also, when it failed there was no spark at coil or plugs and the diagnostic check showed module, coil, rrr egg lays behaving properly.

Damn autcorrect! Module, coil, and relays.

 

[alldodge]

As before, post a pic of the ECM
Has the distributor cap been changed?

 

[tluns]

I cant right now. ECM is on its way to San Diego. Yes cap was changed but that wouldn’t matter as there was no spark from coil.

 

[QBhoy]

I cant right now. ECM is on its way to San Diego. Yes cap was changed but that wouldn’t matter as there was no spark from coil.

It’s not a normal coil and Diz. Not really a coil and diz at all, to be honest.

 

[tluns]

It’s not a normal coil and Diz. Not really a coil and diz at all, to be honest.

It’s not a normal coil and Diz. Not really a coil and diz at all, to be honest.

How do?

 

[tluns]

How do?

How so?

 

[tluns]

Update: ECM on its way back. No issues.

 

[achris]

It’s not a normal coil and Diz. Not really a coil and diz at all, to be honest.

???

But every definition of an ignition coil, it's an ignition coil... (a transformer used to increase the voltage to jump a spark plug gap) Like this...

And the distributor is actually, a distributor. A lead attaches the centre post of the cap to the coil (the one that isn't a coil ) and electrical pulse moves through the centre post, onto a rotor (I assume the rotor isn't a rotor either), and on to the post that the end of the rotor is facing. From there it goes along the plug lead attached to that post, to the spark plug. The distributor, distributes the spark to the right spark plug. That's why it's called a distributor.

 

[tluns]

That’s sort of what I was thinking. The only real difference I see is the pickup isn’t off the distributor but off the ECM via the crank position sensor I would assume.