Mr1 intermittent cylinder drop.

[bronze_10]

My port engine has an intermittent cylinder drop issue. At first I thought it was trash when it cleared up suddenly and ran fine the remainder of the day.. to day it did it again.. when it clears u cN feel the engine surge back to full power.. (its subtle but I can feel and hear it.) I have a temp gun and the front cylender seems to running cool compared to the other engine. Then when it clears it runs the same temp. Today it did it again... so its. ot trash... what does the collective wisdom of the forum say? Plug? (I put them in during thr fall of last year after my bimini ecm issue) or the coil pack? Or something else..

I unplugged the number one could pack and the engine sounded the same..

With it coming and going like that I think it could be a coil pack....

Thoughts...

 

[Beachbummer]

Switch coil to other engine to test if it's the coil?

 

[Brandon_SC]

@bronze_10 I had a spark plug issue on the water yesterday... my symptoms were erratic rpms on my port engine... rpms would drop, be erratic, and then jump back up... run, then drop and fluctuate again. Replaced all four plugs with 4 old spares I kept on the boat, and she purred like a kitten 8 miles back to the ramp for sunset. This was the first time I’ve ever had this issue. I hope that a plug change remedies your problem, and hopefully not a coil.

 

[Julian]

I'd start with a plug change....

 

[bronze_10]

@Brandon_SC that is what mine was doing. Would run fine then the engine would drop and then come back a few min later. I have never had an issue with plugs but I change them often. Funny thing is I keep some extras on the boat but over the winter I removed the tools to replace one! . I found a new coil on line for 22 bucks. I ordered it and figured it may not be a bad thing to have onthe boat anyway. I'm gonna replace all 4 and see how that works first.

 

[bronze_10]

Well.... what does the collective wisdom of the forum say? I think I should not have been cheap and just swapped them this spring like I did the starboard engine...



The one on the left is the cylinder closes to the bow!

 

[Gym]

@bronze_10 I had a spark plug issue on the water yesterday... my symptoms were erratic rpms on my port engine... rpms would drop, be erratic, and then jump back up... run, then drop and fluctuate again. Replaced all four plugs with 4 old spares I kept on the boat, and she purred like a kitten 8 miles back to the ramp for sunset. This was the first time I’ve ever had this issue. I hope that a plug change remedies your problem, and hopefully not a coil.

Good move. I always keep all 8 used plugs onboard as working spares.

 

[Gym]

Well.... what does the collective wisdom of the forum say? I think I should not have been cheap and just swapped them this spring like I did the starboard engine...

View attachment 95269

The one on the left is the cylinder closes to the bow!

@bronze_10 I see 2 brown bands around the plug brand that looks like it was arcing. I think you had a high tension leak. The spark plug electrode was probably cracked or broken creating an occasional lower resistance through the side of the plug. If you pull that #1 coil pack you will probably see a corresponding mark inside the rubber boot.

 

[bronze_10]

Ahhh i see it... let me ask u a question. Qhen u place the coil over the spark plug, work it all the way down there is a small bolt that u screw in to hold alignment. That number one bolt doesnt grab any threads.. I swapped for a different bolt but it nearly grabbed threads. Is that bold just ther to hold could boot in place? Or is it some kind of ground for the coil pack?

 

[Gym]

Ahhh i see it... let me ask u a question. Qhen u place the coil over the spark plug, work it all the way down there is a small bolt that u screw in to hold alignment. That number one bolt doesnt grab any threads.. I swapped for a different bolt but it nearly grabbed threads. Is that bold just ther to hold could boot in place? Or is it some kind of ground for the coil pack?

It just prevents the boot from vibrating off the plug. I could only go by your pics on that #1 plug. If they are brown they are likely burn marks. Again you may want to check the rubber boot on that coil pack to see if it has a corresponding burn mark.

 

[bronze_10]

I ordered a replacement coil pack... it should be here tomorrow morning. I'm gonna take it with me and take the boat out on the lake tomorrow afternoon... I'll run down to the dam and back and see how it does. If the systems persist I'll swpa the coil assembly. The number one cylender was the one that I suspect was the issue.

 

[Beachbummer]

You may want to retap that machined hole with the closest greater thread to have a working bolt in there.

 

[Beachbummer]

I recently looked at the book and the spec for torque was like 5 in-lbs.. That's like hand tight and then blow on it (An exageration, but I bet not far)

 

[bronze_10]

You may want to retap that machined hole with the closest greater thread to have a working bolt in there.

It will stay... it will grab the first thread but once its hand tight it skips out of it. So I just turned it to the point just before it skips. Cant put a wrench on it but it will stay and if the only thing it does it hold the coil boot on then it is good. In my mind I was making it more complicated than it was thinking maybe that was a ground for the coil or something.

 

[Beachbummer]

ah, ok. Blue Loctitie is good for those if you ever feel its backing out.

 

[bronze_10]

Well... that didnt fix it.. still down one cylender. I brought my yds software and performed some tests... its definately the number one cylinder .. but I think it is an injector.. when doing the stationary injector test fire there is no sound from injector one.... anything I can do while I am sitting on the water with the yds in my lap?

@HELP

 

[Beachbummer]

Do you have a voltmeter? Can you check if the voltage jumps for the injector by probing the connector while you run the test?

That will tell you injector vs ecu.

 

[bronze_10]

No... not unless the yds can co that somewhere

 

[Beachbummer]

No, but testing the injector can be done on the bench later too, so no big deal. Maybe others have a thought?

 

[Beachbummer]

If you end up needing to remove the injectors, please take video or lots of pictures. It's a job in my near future and I could use some help. Best of luck on it.