Bizarre Ignition problem 2010 MPI 5.0

[Goodguy9684]

Ok. This is kind of my last ditch effort for help. Real quick I've been in the Automotive repair field for 20 years almost all with GM. so I am very familiar and capable to diag and repair mechanical devices......but I have truly met my may and have been brutally humbled by this current problem.

I've got a 2010 Ebbtide Bowrider with a Mercruiser MPI 5.0. This thing has ran flawless since we bought it used 3 years ago. I decided that after 3 years of use it was time to do some PM service over the winter.

New Cap, Rotor, Wires, Plugs, Fuel filter oil and filter, impeller. All factory Mercruiser replacement parts. OEM everything.

And this is when my nightmare began. For some unknown reason I have no spark on Cylinder #1 and Cylinder #2 has spark on start up then after about 10 seconds it goes dead as well. All the rest of the cylinders fire on point.


I have triple checked all my work. Checked all grounds. Battery voltage - 12.5. Changed coil, ignition module. Put the original cap and rotor on....still same problem. Purchased a 2nd cap and rotor kit still same problem. Tried the old wires....same problem. Check resistance on new wires. All are within spec. I've went step by step through the service manual diag chart. The harness and all connections are good. Did a wiggle test of harness while running.......no change.

I've been beating my head for a week now and I've never come across an ignition problem like this. For the life of me I can't figure out how I developed this problem just by doing basic preventative maintenance.

I'm only left with one idea and that is there's a problem with the ECM. But I'm still not 100% convinced that is the problem.

​​​​​​Can anyone provide any assistance or suggestion. This is actually my wife's boat and she is dying to go out on it....she calls the boat " My Happy Place" and usually it is but right now it's my living hell. I'm usually pretty good at figuring these things out but I have to admit this one has me beaten.

 

[alldodge]

What is the engine serial number?

With 2 cylinders not firing, the motor should run, just not very well, Does it run?
If it doesn't start, does the tachometer show at least 300 rpm when cranking?

What do the plugs in those cylinders look like?

 

[Bondo]

Ayuh,...... Welcome Aboard,...... The guys that do these electronic motors are goin' to want the serial number of the motor,.....

 

[Bt Doctur]

but being a MPI you should have a crank position sensor plugged into the timing cover

 

[Goodguy9684]

What is the engine serial number?

With 2 cylinders not firing, the motor should run, just not very well, Does it run?
If it doesn't start, does the tachometer show at least 300 rpm when cranking?

What do the plugs in those cylinders look like?

Serial no: 1A604574

The engine does run but poorly. Cylinder 1 is clean just fuel on it since its not firing. Cylinder 2 has some residue on it but not much mostly just raw fuel. The idle is around 800....though for some of reason the tach reads 2000 at idle now......just one more thing to deal with.

Yes there is a CKP sensor in the front cover.

 

[achris]

Before you do anything else, get a computer with the Diacom software on it hooked up. Is it spark that has gone (and you've confirmed that) or is it the cylinder 'not firing'? ECU doesn't actually know which cylinder is which. It just gets a TDC pulse from the CPS and fires the coil at the right time. It's the distributor and cap that determines where the spark end up...

Chris....

 

[alldodge]

You do need to scan the motor, this way it would help a bunch usually. Been looking thru the manual and it wasn't much help. Going thru the steps it goes until it checks for spark on all cylinders. If it doesn't have spark on all, it sends you back to looking for power.

Do you have a Cam position sensor on the distributor? Thinking maybe it might have been disturbed. If not something like that it leads to Crank sensor as Chris mentioned. Just thinking that maybe something was disconnected partially somehow.

Hey muc Fun Times have any thoughts?

 

[Goodguy9684]

Before you do anything else, get a computer with the Diacom software on it hooked up. Is it spark that has gone (and you've confirmed that) or is it the cylinder 'not firing'? ECU doesn't actually know which cylinder is which. It just gets a TDC pulse from the CPS and fires the coil at the right time. It's the distributor and cap that determines where the spark end up...

Chris....

There is NO spark. I've even inspected the cap. Every post has arch markings from the spark transfer from the rotor tip to the cap post EXCEPT for No. 1 cylinder. So this is where I've hit the road block. There is spark on each cylinder in side the distributor Except #1. So I'm left with What would cause that. The CKP Sensor only triggers when to fire but it doesn't care about which cylinder. So since it fired all others why would it only exclude 1 cylinder.

I do not have access to a scan tool. I'm not getting any alarms. The alarm system is fuctioning. If I unplug sensors i will get an alarm. It will go away as soon as I plug the sensor back in.

I do have a cam sensor in the dist. From what research i can find i don't see what role this sensor plays since I've read some MPI engines don't even have one

 

[alldodge]

MUC can explain better, but the Cam sensor can cause the CPS to send incorrect signals

 

[muc]

1A604574 ** NOT REGISTERED **

This serial number is affected by Service Bulletin MC-2010-012. This service bulletin needs to be addressed. Please complete the required service work regarding this issue.

Engine was never registered with MerCruiser, so you should get with a dealer to get that done. The open recall has to do with the power steering cooler, so that's not the problem. But not being registered does cause problems for someone like me. A couple of things can happen. One, sometimes there are multiple recalls/service bulletins issued for the engine but because the first one couldn’t be delivered the rest of them won’t get listed to the website. Two, when a tech goes to find the diagnostic information they will get bad information. In this case, it’s directing me to the PCM555 info and I know that can’t be right because a PCM controller only works on engines with multiple coil packs. So please get with a dealer or MerCruiser and get this registered in your name.

Now please don’t take offense, but I have no idea of what you’re knowledge level is. You did say that you replaced the coil/IC module when the chances that that could cause this symptom is almost zero. And that’s an expensive part if you used a MerCruiser part, if you used aftermarket, put the OEM one back on.

Is it possible that you have a couple of bad spark plugs? How exactly have you determined that you have no spark on these cylinders?

Is it possible that the distributor got moved during the tuneup? That won’t change the timing but can send the spark to the wrong cylinder.

As as you can see I’m kind of focusing on something you might have messed up because at this point that is the most likely cause. Did you gap the new plugs? That can cause problems. Did you get the new wires in exactly the same place? That can cause problems.

I do understand that this problem could be something new and not have anything to do with the work you have done. Unfortunately diagnosis of this symptom without a scan tool could be tough.

The cam cam sensor has been brought up. Basically all it does for this engine is speed up how long it takes the ECM to find number one cylinder. The only times I’ve seen it cause weird symptoms like this is when someone has replaced it with a aftermarket part. If you want to test it without a scan tool, just unplug it. The engine could take a little longer to start and set a code but will run without it.

 

[Goodguy9684]

Everything i replaced was with OEM Mercuriser parts except the spark plugs which are AC Delco which i did gap each one at factory spec .060. i replaced with the same. The wires are Mercruiser. Ive checked the connection to each cylinder and the resistance of each wire - all normal.

As i explained earlier. There is NO spark from the plug or the wire or the no. 1 cylinder distributor post. There is no sign or evidence of spark on the inside of the dist. cap. As in my first post i explained that ive been a tech for 20 years so this isnt my first rodeo. Ive went through the service manual diag charts which have not lead to a solution.

the distributor was never removed or adj. I never even touch the securing bolt. Its is tight and the distributor has not moved.

im reaching out here to see if there is a chance that i over looked something. I keep getting the same question...about if there is or is not spark and how i know. I have checked EVERY cylinder for spark with a spark testing tool. Every cylinder has spark EXCEPT #1. And again #2 has spark for about 10 seconds after start up then its spark stops as well.

i was definitely unaware of the registration issue i will resolve that ASAP! THANK YOU!

 

[muc]

Everything i replaced was with OEM Mercuriser parts except the spark plugs which are AC Delco which i did gap each one at factory spec .060. i replaced with the same. The wires are Mercruiser. Ive checked the connection to each cylinder and the resistance of each wire - all normal.

As i explained earlier. There is NO spark from the plug or the wire or the no. 1 cylinder distributor post. There is no sign or evidence of spark on the inside of the dist. cap. As in my first post i explained that ive been a tech for 20 years so this isnt my first rodeo. Ive went through the service manual diag charts which have not lead to a solution.

the distributor was never removed or adj. I never even touch the securing bolt. Its is tight and the distributor has not moved.

im reaching out here to see if there is a chance that i over looked something. I keep getting the same question...about if there is or is not spark and how i know. I have checked EVERY cylinder for spark with a spark testing tool. Every cylinder has spark EXCEPT #1. And again #2 has spark for about 10 seconds after start up then its spark stops as well.

i was definitely unaware of the registration issue i will resolve that ASAP! THANK YOU!

The reason I’m asking exactly how you know about the spark is I’ve wasted a lot of time on the phone with other techs about testing for spark only to find out they are using a timing light to test. And while that will work 9 out of 10 times we might be dealing with that 1 out of 10.

So why is it too much trouble to tell us how you know? What is your Kv reading? What distance is the spark jumping on a gap tester?

You don’t say what spark plug you used, but these newer plugs aren’t made to have the gap adjusted. It ruins their coating.

The reason i asked about the wires is if they aren’t routed properly they can cause issues with EMI.

I’m asking about the easy stuff first because it’s easier. Have you moved #1 and #2 plugs to different cylinders?

i ask about the distributor because there is a service bulletin on it drifting out of spec due to engine hours. Have you checked to be sure it’s indexed correct?

 

[Goodguy9684]

Well after some trial an error I came across something interesting. I discovered that when I unplug the cam sensor in the distributor then start the engine #1 cylinder starts firing normal. As soon as I plug the sensor in the spark on #1 goes dead. Could this be an indicator that the cam sensor sensor is faulty or could this be a problem else where that just shows up when the cam sensor is unplugged.

 

[Goodguy9684]

So here is what ive come up with. When the CPS (cam sensor) is UNplugged, Cyl. # 5 and #7 die but cyl. #1 &2 fire normal. If i turn off the igntion plug the CPS back in then restart the engine cyl. #5 & #7 fire normally but then cyl. #1 & 2 go out. This is the craziest thing ive ever dealt with!!