2018 AR210 running rough below 3k RPM

[Coryd]

Hi all, trying to troubleshoot an issue with one of the TR-1 engines in my 2018 AR210. Boat has 420 hours on it and the starboard engine recently started running super rough under 3k RPM. Above 3k RPM, it runs fine with no noticeable power loss. Under 3k RPM, there is a lot of vibration from that engine and you can see it shake way more than the other engine when looking at it. There aren't any irregular noises coming from the engine and it starts right up. I made sure the pump is clear of debris so it's not a pump issue. Oil was changed 20 hours ago, air filter is clean, and just changed the spark plugs today. I doubt it's an issue with bad fuel as the other engine runs perfectly and the boat is used every weekend. Any ideas what else it might be?

 

[marcham]

I'd start with easy stuff... is a cylinder not firing?

 

[HawaiiBreeze]

Ditto on the above comment. Go through each plug wire. Reminds me of my vehicle (V6) with the coil over set up where a boot had just dry rotted and low rpm sucked. The spark was jumping out the side of the boot. Replaced the boot and it was all good. Good Luck.

 

[Coryd]

I think all cylinders are firing fine, old plugs all looked similar when I pulled them and there’s no excessive fuel smell in the exhaust. The coils/boots still look brand new. I posted my question in the Greenhulk PWC forum too and they mentioned cleaning or replacing the injectors so I think I’ll try pulling the injectors to see what they look like.

 

[FSH 210 Sport]

To be sure swap the coil packs between the engines.

Have you ever had the valve clearances checked?

Does the motor start and idle okay?

 

[Coryd]

To be sure swap the coil packs between the engines.

Have you ever had the valve clearances checked?

Does the motor start and idle okay?

I’ve never had the valve clearances checked and the engine started fine and idled at the correct RPM, just super rough.

I pulled all the injectors today and cleaned them. Still ran rough so I swapped the injectors from the other engine, still ran rough. Then I swapped the coil packs, didn’t help. A guy in the Greenhulk forum also suggested I clean the throttle body and check for carbon build up behind the plate as I guess that’s common in the TR-1’s. Did that and found a tiny bit of carbon and some oil-type residue. Cleaned all that up, still idled rough but then I revved it to about 3500 for a second and it smoothed out and runs fine now. Not sure what the hell it was but I ran it on the hose for a few minutes and it stayed running fine so who knows.

 

[Cobra Jet Steering LLC]

It's Christmas magic !

 

[Coryd]

It's Christmas magic ! View attachment 168655

Ha, guess so! We’ll see for sure when we take it out Sunday.

 

[David Martin]

Three things I would look at first compression on all 4 cyl. Second if compression looks good I would look at fuel injector spray............last is fuel pressure if it drops at lower rpm the engine will starve, and run rough.

 

[FSH 210 Sport]

I’ve never had the valve clearances checked and the engine started fine and idled at the correct RPM, just super rough.

I pulled all the injectors today and cleaned them. Still ran rough so I swapped the injectors from the other engine, still ran rough. Then I swapped the coil packs, didn’t help. A guy in the Greenhulk forum also suggested I clean the throttle body and check for carbon build up behind the plate as I guess that’s common in the TR-1’s. Did that and found a tiny bit of carbon and some oil-type residue. Cleaned all that up, still idled rough but then I revved it to about 3500 for a second and it smoothed out and runs fine now. Not sure what the hell it was but I ran it on the hose for a few minutes and it stayed running fine so who knows.

Hopefully it just keeps on running fine and life is wonderful!

 

[Coryd]

Well, about a minute after putting it in the water yesterday, it went back to running roughly again. It sounds and acts exactly like it does right after spraying fogging oil in, where it bogs down for a second but mine seems to stay bogged down at low RPM. The thought of the oil being overfilled did come to mind but the air filter and air hose are perfectly clean and I cleaned a very small amount of oil and carbon from the throttle body. I'm also very meticulous about putting the exact same amount of oil that I pumped out back in during oil changes. I feel like it has to be something fairly simple that I'm overlooking but I'm stumped at this point.

 

[Fordman]

I know you said you swapped all the coils from one engine to the other, but did you swap all the spark plugs from one engine to the other?

 

[Coryd]

I know you said you swapped all the coils from one engine to the other, but did you swap all the spark plugs from one engine to the other?

Before I pulled/swapped the injectors and coils, I put brand new plugs in both engines. The old plugs had a little over 100 hrs on them but didn't look bad and no oil or anything on them. All the plugs from both engines looked very similar in terms of wear.

 

[Cobra Jet Steering LLC]

By chance do you wash down the exterior of your engines after use, using a water hose ? if so DON'T ! Also get some silicon spray and un-plug every connection you can find on your engine , spray the parts and reconnect them , then clean your ground wires at the engine.

 

[Coryd]

By chance do you wash down the exterior of your engines after use, using a water hose ? if so DON'T ! Also get some silicon spray and un-plug every connection you can find on your engine , spray the parts and reconnect them , then clean your ground wires at the engine.

I don't spray them down after every use, just maybe once every 3-4 months and when I do, I use a light mist, let it dry, and then spray with Yamashield. I haven't rinsed them for at least a few months though. The engine bay stays super clean and the little bit of water that runs through from the ski lockers gets dried every time. Very little water, if any, comes out of the drain plug at the end of the day. I also keep it in a garage with all the hatches and engine bay open to make sure everything dries out. I'll check the connections but the ones I have checked were dry and look brand new. The fact that whatever it is cleared itself on Friday, ran fine on the hose for a few minutes, but then started doing it again once it was in the water baffles me.

 

[Coryd]

Well, I just now went out to look it over again on the trailer, started it and revved it a couple times, and it's back to running normally again. So the variable affecting it seems to have something to do with either being in the water or being under load. But then again, it's only at low RPM's and no perceived power loss so super confused on what the hell this could be. It really sounds like something is somehow getting in the air intake, exactly like when fogging the engine, and it runs rough. No water in the boat, no hoses loose or disconnected that I can see, air filter is still dry, everything in the pump is fine (it was actually pretty much all replaced around this time last year) so I'm at a loss.

 

[Cobra Jet Steering LLC]

hmmm un hook the air box intake hose and see if it runs ok without the air filter in the game, also when you run it on the trailer how much water exits the muffler when you first start it ?
If the engine giving you the trouble is holding more water that it needs it will create more back pressure in the exhaust and cause the engine to run bad and damage the exhaust valves but it is not all that common.

 

[Coryd]

hmmm un hook the air box intake hose and see if it runs ok without the air filter in the game, also when you run it on the trailer how much water exits the muffler when you first start it ?
If the engine giving you the trouble is holding more water that it needs it will create more back pressure in the exhaust and cause the engine to run bad and damage the exhaust valves but it is not all that common.

I actually had the air filter out this last time I ran it and it ran fine. When I first start it on the trailer, it takes a couple seconds for water to start coming out of the exhaust port, nothing appears out of the ordinary there in comparison to the other engine. And I always rev it a few times after shutting off the flushing water to clear some of the water out. Again, nothing seems out of the ordinary with the amount of water coming out.

 

[Cobra Jet Steering LLC]

ok if it runs good without the air box I would try replacing the air filter in that box

 

[Coryd]

ok if it runs good without the air box I would try replacing the air filter in that box

It did run fine without it but it's not like it immediately cleared up when I took it out. I removed it, started it and it was still running rough, then I revved it a couple times and it went back to running normally. Basically, the same situation as the first time (last Friday) it was on the trailer when I revved it and it went back to normal. Except the first time, the air filter was still in there. So I'm not sure the air filter is the culprit as it's almost new (replaced earlier this year) and very clean.