2019 RXP-X timing surge at 7000 rpm

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08-29-2023
truckmann

3 Attachment(s)

2019 RXP-X timing surge at 7000 rpm

I just can't figure this out. I can't find anything wrong but this ski won't run much over 8000 rpm @ 71 mph. The most annoying thing is a bad surge at around 7000 rpm. The logs shows the timing with a significant drop in that area at 140-160 kPa and I have no idea why. The tune is mostly stock with mainly speed limit removal and I don't see anywhere in it that should be pulling timing and KR isn't an issue. This is driving me nuts. Does anyone have any ideas before I run this thing into the rocks and let it sink?

It has an IMUK delete, intake girdle, Fizzle intercooler, Fizzle hoses with BOV, Worx catch can, and a 90 rear intake. New plugs, Rotella T6 oil not over filled. Compression is 130-135 for all cylinders. I set the supercharger slip to 15 ft-lbs. New wear ring, new 21+ impeller. I also tested it with a new MAP sensor today with no improvement.

I will say the AquaSport IMUK delete kit is shit. Don't buy it. It's not made right and requires a bunch of extra plastic to be removed to fit. However, I don't think it's leaking so I don't think that's my issue, but I'm pretty lost and open to any suggestions at this point.

I have a few other logs from today, but this one looks to show the surge issue the best.

Attachment 136342
08-30-2023
Tbranella

try raising your rev limiter to 8800 and see if you get more rpms.
just want to see if theres another limiter in play.
08-30-2023
truckmann

Quote:

Originally Posted by Tbranella

try raising your rev limiter to 8800 and see if you get more rpms.
just want to see if theres another limiter in play.

I'll give it a try. I'm totally baffled at what's going on.
08-30-2023
racemonkey

Did you modify values under Torque Model -> Optimum Torque ? If yes try putting it back to original, when I increased the 180 engine load row to 100% it caused some weirdness.
08-30-2023
truckmann

Quote:

Originally Posted by racemonkey

Did you modify values under Torque Model -> Optimum Torque ? If yes try putting it back to original, when I increased the 180 engine load row to 100% it caused some weirdness.

Yes I did on a suggestion from someone and that is right in the area it starts acting up. Putting that table back to stock right now.
09-01-2023
truckmann

The surge is gone and it feels so much better! It's still maxes out at only 72 mph @ 8000 ish rpm but I'm so glad that surge is gone. I'm still at the lake so I haven't looked at the log yet.
09-01-2023
racemonkey

Nice!

Hard to say why its not pulling more RPM, ignition timing is there and throttle is fully open. No signs of any limiters holding it back otherwise either ignition or throttle angle would show it. It looks like the motor is simply not making the power.

Did you try going for a ride with the seat off? This would rule out exhaust gasses leaking into the hull which would reduce oxygen.

Stock impeller?

Get a wideband installed to rule out fueling issues.
09-01-2023
truckmann

1 Attachment(s)

I've tested with the seat off before. Picked up maybe 1-2 mph. I'll try it again though.

New 21+ oem impeller. (I got it cheap)

Might not get to it until next year, but a wideband is on my list. I might buy the Riva race plate just for the 02 sensor port so I don't have to mess with drilling and taping the manifold.

I actually have a PLX SM-AFR, but I think it's a version 1 so it's probably best if I get something newer. lol

On another note I also changed out the IMUK plug. I don't really think it was leaking, but the MAP sensor hole wasn't as tight of fit as I'd like and the AquaSport one is a shit design. You can see here they didn't put the recess in for the lip that's there after drilling the hole so you have to remove the whole lip to get it to fit.

Attachment 136477

I really need to clean the hard water spots off bad.

If anyone needs a new map sensor this one sure looks to be exactly the same as the OEM one for dirt cheap. If it's a knockoff I sure can't tell. I didn't really need it but it was a cheap check.
https://a.co/d/dGOlOAg
09-03-2023
RUTHLESS

Quote:

Originally Posted by Tbranella

try raising your rev limiter to 8800 and see if you get more rpms.
just want to see if theres another limiter in play.

raise limiter to 8800 with our retainers oh wow
09-13-2023
Tbranella

Quote:

Originally Posted by RUTHLESS

raise limiter to 8800 with our retainers oh wow

you of ALL people should know raising the rev limiter does NOT mean you'll see more RPM's.. ;)
and my suggestion to raise the rev limiter was to see if there were any other RPM based limiters still affecting his tune. (I know for a FACT there's one that most people miss. ;) )
09-13-2023
truckmann

Quote:

Originally Posted by Tbranella

you of ALL people should know raising the rev limiter does NOT mean you'll see more RPM's.. ;)
and my suggestion to raise the rev limiter was to see if there were any other RPM based limiters still affecting his tune. (I know for a FACT there's one that most people miss. ;) )

It's all good with me, I know what you meant. I made a tune for it, but I never got around to loading it. The temps cooled down last weekend a little and it got up in the 8160-8200 rpm range so I don't think I've got any limiters still causing issues. I figure there's either some kind of drag on the ski holding it back or it's just not making full power for some reason. As soon as I get all the stuff I need I'll get my wideband installed and see how the fueling looks. The weather has also cooled down even more here this week.
09-14-2023
Tbranella

Quote:

Originally Posted by truckmann

It's all good with me, I know what you meant. I made a tune for it, but I never got around to loading it. The temps cooled down last weekend a little and it got up in the 8160-8200 rpm range so I don't think I've got any limiters still causing issues. I figure there's either some kind of drag on the ski holding it back or it's just not making full power for some reason. As soon as I get all the stuff I need I'll get my wideband installed and see how the fueling looks. The weather has also cooled down even more here this week.

Quote:

Originally Posted by RUTHLESS

https://www.youtube.com/watch?v=GCjqnRPr7_E

nice! I'm doing 82 @ 8400rpm just a tune, 13/18 and 4" rear air intake.
09-14-2023
RUTHLESS

Quote:

Originally Posted by Tbranella

nice! I'm doing 82 @ 8400rpm just a tune, 13/18 and 4" rear air intake.

oh nice we getting 81 @8180 with oem prop with our 13/17.5 we get 8400 rpms we get 83-84