5.7 Vortec Excalibur Knock Sensor

[Muzzab]

Hello from Australia to all my Nautique friends.
Been lurking on this forum for many years as its a wealth of information on these fantastic boats.

I have been lucky to own two Nautiques having converted from a Flightcraft.

First was a 1994 Ski Nautique with the Pro-Boss.
and the current ride a 2004 Team 206 with the 330 Excalibur. 203 hours young.

My problem is the knock sensor warning keeps occurring and I'm running out of options to fix this problem.

Process so far.
-Original sensor replaced and fault code cleared via Diacom. Fault reappeared " See Dealer-Knock Sensor "
-Checked the following 1- Traced the wire back to the PCM-No problem
2- New Knock Sensor installed and tensioned OK and not installed with thread tape.
3-Check and set the Cam Retard to spec on the Diacom (42 - 47 Deg. )
-Ran the boat on the trailer and the warning fault had disappeared.

Put the boat on the water and as soon as it was under load ( skier in tow ) the fault reappeared ( Knock Sensor- see Dealer).
We do not have the extremes of temperature here in OZ so winterisation is not an issue for me.

I had seen on other sites that you may be able to mount the sensor remotely to "De sensitize " the sensor. Has anyone tried this???

I have to take the boat to the dealer every time to clear the code so this issue is starting to sour the Nautique experience.

Any advice would be appreciated

[Nautiquehunter]

Are you sure the sensor is working and you do have a spark knock [detination] at high load?

[Muzzab]

Knock Sensor

Are you sure the sensor is working and you do have a spark knock [detination] at high load?

Thanks for the information.

I have checked the old vs. the new sensor on the bench with a multimeter and can see an AC voltage output from each sensor when you tap the threaded end of the sensor.

How would I check if there was a spark knock at high load ?

[Muzzab]

Hi. Still have the Knock sensor issue re-occurring.
Re-set the error code on the Diacom and went out to test two different set ups.
First was with an extension fitting on the knock sensor. ( see picture )
Second was a right angled fitting bolted to the front of the engine next to the harmonic balancer.( see picture )

Both times the error code appeared only after accelerating to around 3000rpm.
No error is present at slower speeds.

Also checked hat the engine has had the up-dated / recalled coil to distributor cap wire replaced.

This does indicate that the is detonation at higher speeds but I'm at a loss to solve the problem.

Any advice would be appreciated.

[Paxdad]

I believe that your problem is associated with the fittings located on the sensor. The sensor should be mounted directly in the engine block. Just thinking out loud is that the fitting is interfering with the frequency at which the sensor detects a knock in the motor. The sensor acts like a microphone of sorts and is set to signal the ECM in the event of extreme detonation knock.

[Paxdad]

I also just noticed in the second photo that you have the sensor located on the front of the block just under what appears to be the harmonic balancer. I have never seen one in the location shown. Most all of the knock sensors are located opposite one another on the side of the block as seen in photo 1. This could also be a contributing factor.

[Muzzab]

Thanks to Paxdad for the reply's.
The two previous post were alternate options I was trying to remove this Knock Sensor problem.



So I now sourced a Genuine Knock Sensor from Nautique parts that arrived today.
Installed in the boat/ torqued to 16 ft/lb and connected the single wire.
Ensured there were no DTC showing on the Diacom.

Went out to the lake and my daughter had a ski with no problems.
My friend had a ski and it came on around 2 minutes into his run on the open lake.
It only seems to happen when we put a larger load behind the boat?? but not when were pulling the skier out , but a distance into his run????
BTW , he is only around 220 lb.

So we cleared the code again via the Diacom. and the fault re-appeared in nearly the exact same scenario.

I have attached the Diacom report to show the parameters and the DTC at the bottom of the report.
However I noticed the DTC says ( 44 ) Knock 2 Inactive.

This is a 5.7 Excalibur engine with a MEFI 4.

Why would it be looking for a second knock sensor signal?

If anyone has any ideas please let me know as I'm nearly out of suggestions.

Is it worth trying to change the Cam Retard away from Specification ( 42-47 Deg )?????
Maybe to retard a few degrees at a time?



Thanks in advance.

[jhersey29]

If you think the sensor is now good take a look at what causes knock. 3 common: Low Octane fuel, carbon deposits, incorrect spark plugs. Low Octane - old gas, water in gas(drain FCC into 24 ounce jar and see if you get water to separate), run higher octane fuel. Carbon Deposits - you might run a bottle of 44k through it to clean up the system. Spark plugs - check that they are tight, not cracked by accident. Wires, cap and rotor good on boats that have them. Correct plugs?
Sent from my RM-877_nam_att_205 using Tapatalk

[Muzzab]

Thanks jhersey29.
I have definitely gone with a few of your suggestions.
1- Removed all the gas and replaced with 98 octane / removed the FCC and replaced the filter.
2-Replaced the spark plugs- even tried to run a lower heat range plug with no success.
3-Checked the leads / cap / rotor and they are all near new.

What is 44K - ???? Not familiar with that here in Oz.
Thanks for the help.

[NautiqueJeff]

Not sure if it is available there or not. Here's what he's talking about:

https://www.bgprod.com/catalog/gasol...ystem-cleaner/

[Muzzab]

Thanks Jeff. I will see if I can find this product or something similar.

[jhersey29]

http://clubsearay.com/showthread.php...7653a926589ad8

Might be of some help. Last post page 2
Sent from my RM-877_nam_att_205 using Tapatalk

[Muzzab]

Hi all.
Was checking the timing " Cam Retard" settings on this engine ( 5.7 Excalibur ) and was going to run the boat at a setting a couple of degrees below spec to see if would remove this " Knock Sensor " problem I cannot seem to get rid off.

The attached photo shows the distributor cap mounting screw touching the inlet manifold when the timing is set to 40 Degrees.That is only 2 Degrees below spec.

Could I ask someone check there engines and post a photo of the distributor and see how much clearance it may have to the intake manifold if it was set to 40Degrees.

Thanks in advance.

BTW , I have found an equivalent product to the recommended K44 which is a "LIQUI MOLY" product fuel system cleaner to remove carbon deposits
I will try this next time out on the lake.

Cheers.

[jhersey29]

The manual shows 43-47. Are you getting the rpms above 1000 when checking?
Sent from my RM-877_nam_att_205 using Tapatalk

[Muzzab]

Hi. Yes I have been running the Cam Retard setting at 43 Degrees and this was set with the RPM above 1000. Viewing the graph on the Diacom software you can see that it only moves around 1-2 Degrees from that setting when running the engine.

I'm more interested in why the DTC that comes up says ( 44 ) Knock 2 Inactive when it clearly shows only one sensor on the 5.7 ?

I'm thinking of running two sensors to the ECU ( one to Jp1 the second to Jp17 ) . Has anyone tried this? Will it harm anything?
Cheers