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

[Dennis P]

My Port side engine did exactly the same thing yesterday, max rpm 6000. It had been stalling on idle the last couple of times out. I pulled the plugs at the beginning of the season and they all looked good , No corrosion on the plug threads, etc, I have a 2008 232 Llimited and the previous owner had been running NGK CR 8EB, the current plug in the heads, and has been running fine the last two seasons, is this the correct plug. Should I be using NGK CR 9EB. I will pull the plugs and see how they look when I return to the marina.

 

[Gym]

@tahmad575 what octane fuel are you running? You can get preignition by using high octane fuel in an engine not designed for it. I don't know if the ECU will adjust for that or not.

 

[tahmad575]

@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

 

[tahmad575]

@Dennis P I believe you have the mr1 engines correct? If so what I can say is definitely check your plugs and get back to us because with my experience I changed them in the beginning of the season and less than half way through the season 5 out of 8 plugs broke on me so let's hope it's just a spark plug issue. Check the spark plug gap as specified by ngk.
If they have been in there from two seasons ago and they are not the specified ngk cr9eb I'd strongly encourage you to change them out for the correct ones. Apparently we're supposed to change them out for fresh ones every season
If you think about it we cruise at 7k rpm and just leave the throttles there, the plugs are firing an insane amount of times per minute, to get a sense of what I'm saying whens the last time you drove your car and left it at 7k rpm for more than a second, let's hope your issue is just worn out plugs if so you'll be back at full power in no time ?

 

[Gym]

Nice pics @tahmad575. Very glad to hear it was only a spark plug issue but am very curious as to what caused it. You asked about fuel additives. I use Yamalube Ring free (similar to your Lucas product) to help reduce carbon buildup and also the marine Stabil as you do. Keep an eye on those spark plugs. I hope they were just a bad batch.

 

[tahmad575]

@Gym Thanks and yeah it's honestly been keeping me up at night, I have no clue like how can relatively fresh plugs just break like that
I just want to know for certain a reason that caused it so we can prevent it from happening to me and anyone else.

I'll post an update tomorrow night once I check the plugs

Where do you get the Yamalube ring free I've been looking at that just trying to find a good price on it, Hoping I can find a bulk sale like what I did for the Lucas and marine 360

 

[Gym]

@Gym Thanks and yeah it's honestly been keeping me up at night, I have no clue like how can relatively fresh plugs just break like that
I just want to know for certain a reason that caused it so we can prevent it from happening to me and anyone else.

I'll post an update tomorrow night once I check the plugs

Where do you get the Yamaha ring free I've been looking at that just trying to find a good price on it, Hoping I can find a bulk sale like what I did for the Lucas and marine 360

I buy it online wherever I find the best price. Usually mid $40 range. I don't know if it's any better than your Lucas product.

 

[tahmad575]

@Gym I like to think since it's Yamaha it's probably better for our engines than Lucas which is universal, my marina charges $70 for the Yamalube ring free so thanks I'll look online ?

 

[Gym]

@Gym I like to think since it's Yamaha it's probably better for our engines than Lucas which is universal, my marina charges $70 for the Yamalube ring free so thanks I'll look online ?

Yup, $50 is close to the top price online.

 

[tahmad575]

Ok maybe they were FAKE? I bought them off Amazon, total came out to $28
Genuine ones at advanced Auto were $9.99 each

Here's a link showing fake amazon ngk irridium plugs....

 

[Beachbummer]

Hey, Hold up.

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.

So as far as I am aware the engines are different, and the HO engine has higher displacement and different components.

If it was the ECU only folks could swap that for the extra 20 hp, and it's not that easy.

You can gamble again, but if you want oem reliability you need the correct ECU for the engine.

Since it runs OK normally I would keep the rpms within the normal range of what the engine did from factory. (I'm confused both engines should Max out at 10k)

Anyone else has concerns with the ho ecu in a non ho motor? Different CCs and different intake in some cases.

 

[swatski]

Correct me if I'm wrong

Not sure how to say it strongly enough (yes, you are wrong) but without sounding like a dick...

Well, let's put it this way: Your new incompatible ECUs are running your engines ~1,500 RPM above redline.
And no, new spark plugs are not likely solve your problem, long term... IMO. I'm afraid if you continue doing what you are doing next time you will not need a borescope but a new engine block.

Sorry I don't mean to sound awful, it's just is not a good idea for a mod, if "non-HO" to "HO" conversion was that easy evryone would be doing it. In reality it is not, there are simply too many internals that need to be replaced.

--

 

[tahmad575]

@Beachbummer @swatski I appreciate it and don't worry the criticism helps
Do you think if I never go over 8000rpm I should be good? When I swapped the ECU's I didn't do it to gain hp I thought it wouldn't be a huge problem and I saved a grand and had the seller overnight them, I still have my two old ECU's and am in the process of sending those in to get repaired, once I get them fixed I'll put those back in and sell the two high out put ECU's currently in my boat

 

[Dennis P]

@Dennis P I believe you have the mr1 engines correct? If so what I can say is definitely check your plugs and get back to us because with my experience I changed them in the beginning of the season and less than half way through the season 5 out of 8 plugs broke on me so let's hope it's just a spark plug issue. Check the spark plug gap as specified by ngk.
If they have been in there from two seasons ago and they are not the specified ngk cr9eb I'd strongly encourage you to change them out for the correct ones. Apparently we're supposed to change them out for fresh ones every season
If you think about it we cruise at 7k rpm and just leave the throttles there, the plugs are firing an insane amount of times per minute, to get a sense of what I'm saying whens the last time you drove your car and left it at 7k rpm for more than a second, let's hope your issue is just worn out plugs if so you'll be back at full power in no time ?

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

 

[swatski]

@Beachbummer @swatski I appreciate it and don't worry the criticism helps
Do you think if I never go over 8000rpm I should be good? When I swapped the ECU's I didn't do it to gain hp I thought it wouldn't be a huge problem and I saved a grand and had the seller overnight them, I still have my two old ECU's and am in the process of sending those in to get repaired, once I get them fixed I'll put those back in and sell the two high out put ECU's currently in my boat

It’s not just RPM/going over the redline, it’s also ignition timing, air fuel ratios etc.

If I were in your position and wanted to continue to operate this boat while waiting for the correct ECUs... I would run it very gently not exceeding 8- 8,500 RPM, whatever it is for non-MR-1, and use premium (93 octane) or highest octane gas I could find - to minimize the risk/effects of preignition/detonation/knocking.
Probably the best you can do...

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[fireflymedic]

Just a note and someone please correct me if I'm wrong. Once you've compressed the spark plug washer ie taking it out and and putting it back in that 1/4 turn may not work as washer is already compressed not sure how much titer you need thought.

 

[tahmad575]

@swatski I'll definitely go easy on it until I get my ECU's back which should be in 4 weeks or less.

I eventually want to replace every single item on the boat with a new part to make it as new as possible in the coming years

In the event that both engines fail on me, could I swap in the high output mr-1 engines?
I know this will stir controversy but how bad of an idea is it to lets say drop in the HO 1.8 TR-1 engine? I know the jet drive has a certain limit but what if I replaced my entire jet drive with the newer one as well?

 

[swatski]

@swatski I'll definitely go easy on it until I get my ECU's back which should be in 4 weeks or less.

I eventually want to replace every single item on the boat with a new part to make it as new as possible in the coming years

In the event that both engines fail on me, could I swap in the high output mr-1 engines?
I know this will stir controversy but how bad of an idea is it to lets say drop in the HO 1.8 TR-1 engine? I know the jet drive has a certain limit but what if I replaced my entire jet drive with the newer one as well?

There is no controversy surrounding it, it is just simply cost prohibitive. MR-1 engines use a different shaft, so you can not just swap 1.8 engine in place of a mr1, you’d have to swap the pump as well, or at least the shaft and the main pump bearing, and impellers. That said, the pump design is almost identical so the MR-1 pump would easily handle 1.8 engine but the modifications are simply cost prohibitive.

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[swatski]

I eventually want to replace every single item on the boat with a new part to make it as new as possible in the coming years

If you get the original ECUs fixed you may not need to change the engines. Sounds like you might have dodged a bullet there.

You could swap the non-HO with HO but that may cost more than a HO boat.

There are almost no performance mods that matter too much in HO MR-1s, per Group K publications, the experts.

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[Beachbummer]

Cheapest option for MR1 HO engines.. Buy 2007+ boat. And sell yours. It seems outrageously expensive, except for all the other ways to do it, which cost even more money.

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.

For the next few weeks I would keep it under 8500. Once you get your ecus you may find the boat still does 10,000. As it should.