Knock Retard Limit warning

[duknowme]

I have a 2020 23 MXZ with the new Monsoon M6Di engine.  I have recently had a check engine warning and the engine diagnostics states, "Knock Retard Limit".  This has been causing the engine to slow on its own and making wakeboarding impossible since it won't maintain speed for more than 10-15 seconds at a time.  Spoke with Dealer and they state this is generally a fuel quality issue.  I have always used 91 octane.  The Manual reccomends 93 octane but I don't know where to find this??   Since this I have used 91 octane ethanol free gasoline and also bought octane booster to try and boost the octane level.  I am still having the issue and the boat is now in the shop.  Any thoughts?

[csleaver]

Many alarms and controlled engine derate (reduced power) are designed to not only to alert the owner when there is a potential engine damaging situation occuring, but limits the amount of power available to prevent severe damage when someone needs to move the boat in an emergency situation as opposed to the engine just shutting off.  If you are not sure why an alarm or power reduction occured, sometimes it is just better to turn the engine off and get a tow back in.  Depending on what the problem is, it could make the difference of the boat being in the shop for a few days or a few months.

Without knowing the SPN FMI code from the alarm it is difficult to look it up in the diagnostic manual for possible causes.  I would expect the dealer to possibly take a fuel sample to check for contamination, take a diagnostic recording from the ECM, then use that data and a diagnostic guide from Malibu to determine possible causes for the alarm and then go through the recommended repairs.  An on the water test after the repair would be a good idea, too.

That is basically what the dealer and the manufacturer warranty is there for.  That way you don't have to take the boat back to Tennessee, or fix it yourself when there is an issue. 

Let us know what they find out.

[23LSVOwner]

8 hours ago, duknowme said:

I have a 2020 23 MXZ with the new Monsoon M6Di engine.  I have recently had a check engine warning and the engine diagnostics states, "Knock Retard Limit".  This has been causing the engine to slow on its own and making wakeboarding impossible since it won't maintain speed for more than 10-15 seconds at a time.  Spoke with Dealer and they state this is generally a fuel quality issue.  I have always used 91 octane.  The Manual reccomends 93 octane but I don't know where to find this??   Since this I have used 91 octane ethanol free gasoline and also bought octane booster to try and boost the octane level.  I am still having the issue and the boat is now in the shop.  Any thoughts?

It will run fine on 91. You could have possibly gotten some bad gas.

 

I also think I heard of a new engine calibration(?) that may help?

[duknowme]

I recently had my 20 hour break in service done per the dealer reccomendations.  The oil level does seem a little high.  Do you think this could contribute to a Knock?

[23LSVOwner]

High oil level can contribute to knock.

[dwc032]

I have the same boat. This past weekend I had the same code SPN731 knock retard at limit.  I will try non ethanol super and see if the code goes away.  Mine went into limp mode or whatever it’s called and I couldn’t go past 8MPH. Limped it back to dock and put it on the trailer. I believe it is fuel related and with either 93 with some startron or non ethanol fuel the code will stop. Hopefully the code goes to inactive and it doesn’t keeep putting the boat in limp mode.  

[csleaver]

Take the boat to you dealer so they can check it out.  Anytime you have an engine alarm that also causes a power derate I would recommend this, especially if it has warranty coverage.

[dwc032]

5 hours ago, csleaver said:

Take the boat to you dealer so they can check it out.  Anytime you have an engine alarm that also causes a power derate I would recommend this, especially if it has warranty coverage.

Yeah I know, it’s going in Tuesday. 

[BlindSquirrel]

Doesn’t the manual say 87 up to 10% ethanol pump gas is okay too. I know I’ve seen that somewhere on my brother’s  m6, whether it was in the manual or a sticker somewhere. Either way, that’s all he runs and just got past the 80 hour mark on this 2019 lsv 25 m6 with no running issues.

Edited August 10, 2020 by BlindSquirrel

[23LSVOwner]

Could be a crappy tank of fuel.

 

You wouldn't believe what I have seen some test out at.

[csleaver]

There are recent service bulletins from Malibu involving some M5 and M6 engines regarding ECM updates for performance enhancements that include octane scaling and temperature regulation, Y-pipe coolant relief valve replacement, and transmission shift valve inspection.  It is difficult to tell if any would apply to a particular boat without the engine manufacture date and ECM calibration information.  That is why it is best for the dealer to identify the cause and correction for these issues.

[dwc032]

1 hour ago, csleaver said:

There are recent service bulletins from Malibu involving some M5 and M6 engines regarding ECM updates for performance enhancements that include octane scaling and temperature regulation, Y-pipe coolant relief valve replacement, and transmission shift valve inspection.  It is difficult to tell if any would apply to a particular boat without the engine manufacture date and ECM calibration information.  That is why it is best for the dealer to identify the cause and correction for these issues.

I talked to the dealer and he thinks its bad fuel. I was told it was filled with non ethanol 93 super when I took delivery. I put 3/4 of a tank through it and then the code popped up. I thought ok bad fuel filled it with non ethanol and code didn’t go away. I am sure the code will need to be cleared in order for it to go away. I have a diacom code reader but didn’t want to clear it so the dealer could see the code and diagnose it. 

[duknowme]

So, I was told that it was bad fuel too.  I did everything all of you have posted here to upgrade the fuel and the code persisted.  Boat Dealer's tech came out on water with me and hooked up the computer in real time to witness the issue.  He sent the info into malibu and next day Malibu sent a software patch.  Software has been updated and boat has run great since.  I am in AZ and you can not find 93 octane fuel.  Best we have is 91.  Since the software update, I have put 25 more hours on it and there has been zero issues with 91 octane fuel.

[Texan32]

10 hours ago, duknowme said:

So, I was told that it was bad fuel too.  I did everything all of you have posted here to upgrade the fuel and the code persisted.  Boat Dealer's tech came out on water with me and hooked up the computer in real time to witness the issue.  He sent the info into malibu and next day Malibu sent a software patch.  Software has been updated and boat has run great since.  I am in AZ and you can not find 93 octane fuel.  Best we have is 91.  Since the software update, I have put 25 more hours on it and there has been zero issues with 91 octane fuel.

it would be nice to know how they actually addressed this.  Did they de-sensitize the sensor by raising the noise floor threshold?  Did they pull timing at a certain RPM or load value?  Did they add fuel where it was knocking to try to quench it? 

I know engine management has gotten very sophisticated.  But if an engine is designed to be able to run on 87 octane (as a minimum), you should not be seeing issues with that fuel.  The ECU may have the ability to increase power when it senses higher octane fuel.  But as long as you are meeting the min. value, it should not pull power. I do see in the 2020 Bu Manuals that they "strongly recommend" 93 octane which makes be think that the ECU might be able to lean out or add timing to boost power.  Also, based on your elevation, 91 may be the highest octane that is available. 

[csleaver]

According to Malibu, 93 octane fuel is recommended for all Malibu engines, but the M5 and M6 can run on a minimum of 87 octane and the LT4 can run on a minimum of 91 octane fuel.  Most engine management systems will retard timing and enrich fueling to prevent knock which also reduces power output.