EX343 misfiring

[MarkL]

Hi all,

Wondering if someone more skilled than me might be able to weigh in here. I have a PCM EX343. Boat starts and runs fine up until about 22-23 mph, and then if sounds like it is misfiring above that. There a hic-cup in the normally steady engine noise and intermittent loss of power. I thought the gas might have water in it b/c its been doing it ever since I got it out of storage. But now with fresh gas, I'm a bit at a loss.

If anybody has some suggestions of how to diagnose the problem, they would be very welcome!

Thanks

[JohnnieMo]

I just recently had some bad vibration and an engine code. Misfiring on all cylinders. Took it to the dealer and they said the distributor was corroded. They replaced it and all the spark plugs. Problem solved. Still waiting to see if PCM will honour it as warranty. IT was about $700 CAD.

I asked if this was normal and they said their tech has seen it once before. So not terribly unusual, but not normal either.

[MarkL]

Would be great if that is all it is. They probably do need to be replaced. Thanks for the lead

[MarkL]

That was all it was. A bad distributor cap. Pretty decent corrosion on it. Thanks again

[JohnnieMo]

Glad to hear it. A relatively cheap repair in the world of boating.

But it sure makes you wonder why a marine grade engine is having these issues....

[IDBoating]

I'm no engine expert, but: Didn't we develop fully electronic ignition decades ago? Why does any engine have a distributor cap anymore? Why bother with the rotating parts, and the contacts, and all the stuff that is subject to corrosion and wear when a nice, sealed electronic module would fix that permanently?

[ericinmich]

The engine controls on boats (gas, small blocks) has until the last few years remained generally what was on cars 20 years ago. Cost and reliability are the main reasons for keeping them so long. Getting rid of the distributor requires newer cam/crank position sensors and target wheels, plus the crank times are a bit longer as things get synced. Not caring which side of the engine you are firing fuel to, and letting the spark choice be done by the distributor is easy and quick.

Newer systems will have about twice as many wires and connectors that can fail... etc.

[IDBoating]

Newer systems will have about twice as many wires and connectors that can fail... etc.

Seems like today's marine engines are already well instrumented. My EX343 (same engine as the TLP) is covered in wires, harnesses, black boxes, etc. I think that page has turned, we're 90% there. Not sure why we haven't finished embracing the last 10% of electronic engine control, when doing so would eliminate all sorts of purely mechanical maintenance problems such as the one highlighted in this thread.

[MarkL]

Dated thread at this point, but i'd just point out something I learned. My 2011 EX343 is basically a '98 GM Vortec 5.7L V8 engine. Can this be confirmed? The harness might be different, but so far the majority of the part are the same.

[h2o-ski]

The long block is the same, however each marnizer adds their own equipment.

The 5.7L has proven to be a reliable engine even with the distributor. My old ranger that I had, had an engine that Ford converted from distributor to electronic ignition. While the engine was bullet proof, I was replacing cam position sensors every 75,000 miles. A distributor cap is a lot cheaper than the cam shaft sensor on that engine.