Mysterious broken spark plugs + Bad compression test (With Pics)

[swatski]

What has me confused is why your boat did not do 10k rpm before. It is rated to do that at Max Rpm if you have a non HO 230.

Are you sure the non-HOs are rated to spin at 10k?

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[Beachbummer]

Yamaha SR230

The SR230 looks like a quality stern-drive but it's powered with four-stroke Yamaha jets.

www.boatingmag.com

I think so. And I have not found anything to the contrary. And I've looked. I've also heard from several owners that were selling their no ho boats reporting the same (when i was buying)

 

[tahmad575]

@Beachbummer the 2007 boats don't have the passenger side captains seat! Lol but seriously though what are the costs involved if you don't mind sharing? I was thinking it would be in the 10k range

so previously with the original ECU's and with new spark plugs new oil I remember only being able to reach 9000 rpm on my port and 8700 on my starboard engine.
throttle cables were also adjusted and the butterfly valves were confirmed to be opened 100% so that was my full throttle rpm, I've only hit 10k with the new ECU's but I sure as hell won't be doing that again now that I know I can risk blowing out my engine doing that

port engine was sbt rebuilt in 2017, starboard is as old as the boat (14 years)

 

[tahmad575]

@swatski I just enjoy the feeling of getting on plane and cruising, I'm not going to lie the speed is addicting

I think what you guys are saying is, it's better to keep this the way it is and restore it fully
More of an all around family oriented boat

If I want something fast, get a two or 5 seater high performance boat maybe in the 20ft range
More of a go fast boys only boat

 

[Beachbummer]

I recently made a mistake in swapping the impellers from side to side, and ended up on a wild goose chase for several months, so I learned a bit about how these engines work.

Max RPM under load is a result of many factors. Hull,pump and impeller condition and impeller pitch, engine compression, timing and sensor feedback, spark plug condition, and air density and flow all play a factor. With the right ecus you can troubleshoot. Any chance your impellers are not original and are more aggressive than originally specified? That would be my first guess for both engines to have this issue at the same time, knowing nothing else.

 

[tahmad575]

@Beachbummer yeah the impellers don't look in the best shape like they have some corrosion, they also wobble back and forth when I pull and thank on them

When I replace them in the winter should I get solas or stock Yamaha impellers?

 

[swatski]

@Beachbummer yeah the impellers don't look in the best shape like they have some corrosion, they also wobble back and forth when I pull and thank on them

When I replace them in the winter should I get solas or stock Yamaha impellers?

You should check the bearings for integrity and water intrusion, by pulling the cones off.

If your ECUs are mismatched, no performance mod or fuel additive is going to solve underlying problems, "performance" spark plugs are not going to help but likely aggravate those issues.
If your pump bearings are shot, aftermarket impellers will truly be just lipstick on a pig.

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[Beachbummer]

Wobble??? That's not good. The shafts are pressed to the pump, and the impeller is screwed on tight. There should be no wobble. I suggest you examine the grease and bearings and go from there.

I just purchased a used solas set and so far so good. My OEM impellers worked fine, I think the solas hook a little better, but no scientific tests from me, so it could be my subconscious trying to justify the expense.

@swatski has it right. Don't need with impeller swap yet, but certainly examine the pumps.

 

[Jgorm]

@Jgorm @Brad460 how do I check for or know what detonation looks like and can you please clarify what that is? Thanks

When I figured out that my ECU's were damaged as mentioned in a previous thread I changed them out with two high output used ECU's I found on eBay. I cross checked the part numbers and they were in fact the 2005 Yamaha sx230 High output ECU's. My boat is the 2005 non high output version but now it has high output ECU's controlling it and definitely providing me with much more power and 1k more rpms per engine. I was under the assumption from reading other threads on here the only difference in the high outputs is a different air to fuel ratio and a different intake / exhaust set up to allow for more air passage. Correct me if I'm wrong

@Beachbummer @Neutron @swatski how do I know if I have installed the plugs correctly? I thought it was pretty straight forward but could you please elaborate your procedure or tips to avoid improper plug seating?

I do it like this: firstly clean the threads with a shop towel wrapped around a screwdriver, apply anti seize to the new plug threads, apply dielectric grease to the part of the plug where the ignition coil will make contact, then I make sure the washer that came with the plug is all the way up and not in the threads, proceed to hand tighten the plug, back out the plug a quarter turn a few times while screwing it in to make sure the antiseize gets applied evenly, then after it's hand tight I use the ratchet to tighten it a quarter turn. Put the ignition coil back on and that's it

Also y'all are right, I used the irridium plugs because I want the best for my boat and thought they'd be stronger but now I truly see there's no difference in the regular and the irridiums, if we're going to be changing them out every season like recommended than it makes sense to use the regular cr9eb plug.

@Gym I'm running 87 octane as specified in the manual, I also add the required amount of stabil marine 360 with each fill up and the required amount of Lucas fuel injector cleaner.
What fuel additives do you guys like to you use? Some say it's snake oil some love a specific brand, I'd like your opinions and suggestions since I'm new to the game

Today I went out on the Hudson River again and the boat preformed really well and smooth, now that it's back in my warehouse since it's raining for a couple days I'll check all 8 spark plugs I installed 36 hours ago, got two trips out of them so far I'll keep you all posted on how they held up.

I appreciate the replies and help
Attached are a couple pics from my trip

You can't run ho ecu on non ho engine because they have different displacement. The afr will not work out correctly. Not sure if they run different injectors or a different map sensor either. All are critical to engine operation. Look for speckled porcelain for detonation. I would never ever run a ho ecu on my non ho engines. Never ever. Been tuning cars too long to know that tiny differences in ecu part numbers can destroy engines. I'd bet money that that is why you have detonation and why you are minutes away from buying new engines. This world be a park the boat situation for me.

 

[swatski]

You can't run ho ecu on non ho engine because they have different displacement. The afr will not work out correctly. Not sure if they run different injectors or a different map sensor either. All are critical to engine operation. Look for speckled porcelain for detonation. I would never ever run a ho ecu on my non ho engines. Never ever. Been tuning cars too long to know that tiny differences in ecu part numbers can destroy engines. I'd bet money that that is why you have detonation and why you are minutes away from buying new engines. This world be a park the boat situation for me.

Okay, that totally making sense, what I had thought all along, I just don't have the knowledge and experience to be able to say it. Glad you did!
Blaming this situation on iridium spark plugs or fuel additives seemed like a complete nonsense.

Yeah, throw a new set of spark plugs in those engines and carry on... (not)

EDIT: too bad it took like three pages of comments for the OP to finally mention the new ECUs were for a different engine...

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[tahmad575]

@swatski I should have included that in the beginning, the guy who sold me the ECU's assured me they'd work in my boat no problem I guess he just wanted to make his money. I made a seperate thread when I first installed the HO ECU's and no one mentioned anything bad about putting in ho ECU's into a non ho boat. I just updated that thread and have attached a pic

@Beachbummer I'm going to replace all the bearings and seals in the jet drive for both engines as well as the wear rings, the impellers don't wobble alot it's about 1mm of play and I'm sure at high speed that makes a huge difference. I don't like how both impellers have corrosion so I'm going to swap them out for new ones

@Jgorm thanks for the info, I was misinformed when swapping out the ecu's. I have my original ones over in California getting repaired. I'll use the originals and sell the high out put ones

Thank you all for the help and for saving my engines

 

[swatski]

@swatski I should have included that in the beginning, the guy who sold me the ECU's assured me they'd work in my boat no problem I guess he just wanted to make his money. I made a seperate thread when I first installed the HO ECU's and no one mentioned anything bad about putting in ho ECU's into a non ho boat. I just updated that thread and have attached a pic

@Beachbummer I'm going to replace all the bearings and seals in the jet drive for both engines as well as the wear rings, the impellers don't wobble alot it's about 1mm of play and I'm sure at high speed that makes a huge difference. I don't like how both impellers have corrosion so I'm going to swap them out for new ones

@Jgorm thanks for the info, I was misinformed when swapping out the ecu's. I have my original ones over in California getting repaired. I'll use the originals and sell the high out put ones

Thank you all for the help and for saving my engines

Thank you for clarifying the situation! Sounds like you have a plan!

As far as the impellers, many members here are happy with the OEM impellers. The OEMs are pitched slightly different for both sides, I believe the Port side has notches in the "neck", and those work really well. I have a feeling that a lot of the time aftermarket impellers get the credit for working better than OEM but in reality it may have more to do with the condition of an OEM impeller being replaced.

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[Dennis P]

Picked up the recommended plugs from the dealer NGK CR9EB, $51 CAD for the 8 plugs. Will be replacing them on the weekend. Thanks

Changed out the spark plugs and now she runs great, #1 and #2 on the port side were dead. so running on two cylinders would explain the lack of power. The starboard was all good till I got to the infamous #3 that wouldn't budge, so I left it alone since I didn't want to break it in the head. Its running well so I'll take a manual impact driver and tap it gently to loosen it up in the fall, don't want to lose the summer season over a cracked plug stuck in the head.

 

[Jgorm]

Changed out the spark plugs and now she runs great, #1 and #2 on the port side were dead. so running on two cylinders would explain the lack of power. The starboard was all good till I got to the infamous #3 that wouldn't budge, so I left it alone since I didn't want to break it in the head. Its running well so I'll take a manual impact driver and tap it gently to loosen it up in the fall, don't want to lose the summer season over a cracked plug stuck in the head.

I had a stuck plug that wouldn't budge (with moderate "non breaking" amount of force. I waited until winter (temps around 60 instead of 100+), put pb blaster in overnight and it popped out easily. Be careful with an impact, I'd use a wrench and go tight, loosen, a few times so you can feel the force and give. Mine was cross threaded pretty bad so i used the other 3 old plugs to chase it out about 8x until it was smooth.

 

[Beachbummer]

If you can find a torque wrench that works both ways, maybe set It to 15 or 20 or some other number you feel comfortable with, and move back and forth as suggested. Good idea to wait until winter. Pb blaster is awesome.

Best of luck.

 

[Dennis P]

Changed out the spark plugs and now she runs great, #1 and #2 on the port side were dead. so running on two cylinders would explain the lack of power. The starboard was all good till I got to the infamous #3 that wouldn't budge, so I left it alone since I didn't want to break it in the head. Its running well so I'll take a manual impact driver and tap it gently to loosen it up in the fall, don't want to lose the summer season over a cracked plug stuck in the head.

I used PB Blaster , let it soak for a couple of weeks, Went back today and out she came. There is no corrosion on the plug ( Happy) , I now remember that the dealer replaced this plug last season, must have been really cranked by the tech! Really pleased that both engine #3 have no signs of corrosion on the plugs.

 

[Ronnie]

A few thoughts after having experienced spark plug problems for the first time ever.
I had plug 2 on the port engine fail on me. When I pulled the plug I found that the ceramic was broken off and the electrode and core were gone. That engine was maxed out at 6k rpm, usually it gets to 7.6k rpm. The ignition coil for that plug was also badly deteriorated (the sleeve that goes over the plug end disintegrated). I ended up doing a compression check and found it had 120 psi whereas the other cylinders came back at 150 psi. I replaced the plug and coil, now that engine maxes out to about 7.3k rpm.

In checking the plugs on th starboard engine I found the second plug in the same condition as the OP (I.e., the center ceramic and electrode were gone). The compression check came back at 115 psi and the other cylinders came back at 150 psi. The ignition coil on the bad plug also showed signs of early deterioration.
What was odd about this is that the engine itself was performing great with the bad plug. I ended up replacing the plug and ignition coil on this engine as well.

I’ve been out twice since replacing the plugs and coils and think the boat is running great. I don’t get to 7.6k rpms max anymore (it’s between 7.3k and 7.4k now on each engine but I attribute that to the lower compression in cylinders 2 of both engines which were probably damaged when the plugs failed).

So what caused the plugs to fail? I’m going with the diagnosis of a member here, Jeff @Cobra Jet Steering LLC , which matches that of my two mechanics / friends, that is when I installed the new plugs last winter I cracked the ceramic part on both, the port side worse than the starboard. The port engine ran fine until the ceramic part that attaches to the ignition coil on the port engine broke off completely so the plug was not igniting the fuel in The cylinder. This caused the rpm in that engine to drop about 25% as expected when you lose 1 of 4 cylinders.

Lesson learned, don’t take changing spark plugs out for granted. That is, use the right high quality parts and tools and take your time to be sure you do not break the plug when you are installing it.

FYI I still use iridiums plugs and replace them every two seasons. There was never any noticeable performance increase but I feel better about using them anyway even at at cost of $10 to $11 per plug. I got a good compression checker at pep boys for around $40 but this was years ago. Don’t be surprise if you need to buy ignition coils the OEM parts are about $120 each on amazon, $250 at my local power sports shop.

I have a bit of experience with the mr1 engines, both ho and non-ho.
The ho has a 1,052 cc displacement, puts out 160 hp at 10,200 rpms.
The non-ho has a 998 cc displacement and puts out 140 hp. I’m not sure what the max rpms are but am sure it is not 10k to 10.2k rpm.

I sent the non ho ecu in to be repaired to a place in Chico CA. It came back a month later drilled and labeled “unrepairable”. The interesting thing about this is it came back in two boxes, the one I shipped it to Chico in which was inside a box from Europe. I think Carmo in Chico is a broker, they don’t actually fix ecus there, they collect them from US customers and send them to Europe for diagnosis and repair.

I couldn’t find an inexpensive ecu for my non ho waverunner so I sold the waverunner to a guy that rents them out locally. He called me back to let me know that another non ho ecu from a different model year worked fine. He went on to say this should always be the case even if the part numbers are different between the non ho ecus, as was the case here. Just need to be sure that you are replacing a non ho ecu with an non ho ecu not and ho ecu.

 

[Jgorm]

@Ronnie non ho will see 10k. I bounce my fx140 off the limiter around 10k when it cavitates.

 

[Ronnie]

Your probably right @Jgorm . I can’t check again until the waverunners come out of storage, around April. Generally I don’t pay much attention to the rpms but I know that my ho fx has a 58 mph top speed where as my non ho fx tops out at 49 in the same conditions. My ho fx also accelerated a lot faster but at least some of this maybe because of the aftermarket impeller installed in the ho fx. In any case, I do not think the Ecus are interchangeable between the two, at least not as a long term solution.

 

[Jgorm]

Maybe the pump or impeller is different?