2006 aquatrax r12x won't go over 4200 rpm

[Kevlarss]

006 aquatrax r12x won't go over 4200 RPM
New ....
wastegate solenoid
Plugs
Air filter
Oil change 4.3 quarts
Both coolant/oil temp sensors
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Turbo turns freely lube w crc 556
Wastegate actuator checks out with air force and diaphragm holds with slight vacuum .
All lines and hoses checked for pinholes, dryrot, splitting
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Ski runs/starts perfectly but limited to 4700 rpms
No codes
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Double check the pill in vacuum hose
Ground oil pressure sensor and works
Pull exhaust manifold and pressure test inspect all turbo parts while disassembled.
All new gasket set when reassembling engine
Again new oil 4 quarts then lowering to 3 quartz
Still same thing 4200 max rpms and runs perfect for hours. No codes
It has to be in a limp mode as if too much oil
It's not in the restricted mode for beginners I have put it there and it revs to the same rpm but then starts cutting out like it supposed to.

Totally frustrated what can I try next my brothers on skis

[NitroShark]

Put a boost gauge on and take a reading at 4700 RPM and report back.

[Kevlarss]

In the water or out....i have 8psi on the trailer

[NitroShark]

You should take the reading in the water.

8 psi boost on the trailer seems to be abnormally high. You should not be revving the motor on the trailer in the first place. ItÔÇÖs not good for the ski.

There is a possibility that you have a case of a shared key on the fly wheel which would give you reduce ignition lead this would cause higher boost at lower loads. But letÔÇÖs not guess, take the reading at 4700 RPM in the water and report back.

Also, I assume you have ran a compression test on this engine and all cylinders are equal At or close to 170 psi while holding the throttle open during testing.

[Kevlarss]

In the water 4700 rpm......6psi
Good compression

[NitroShark]

When you disconnect the line going to the waste gate actuator does the ski Over-boost? It should easily spike to 12 PSI and try to shut down. Do this in the water and be warned it should try to shut off instantly.

Do that, take the reading and report back.

[Kevlarss]

Ok

[Kevlarss]

Mr nitro there was no differences when disconnecting vac hose from wastegate, when ski is out of water it will spool up to 7000 plus rpm until cutoff is reached .. You can hear turbo whine, remember I pulled off the turbo and split it. I examined the compressor wheel blades. I removed wastegate and rem0ved wastegate actuator. Waste gate valve is freely operating I even cleaned carbon and valve seat.....when actuator is installed valve is slammed shut you can't even open it by hand.only air pressure to actuator will open valve

[NitroShark]

There is your problem, little or no boost. Possibly -bad turbo, or leaky intake or exhaust. Revving the ski up under no load on the trailer is meaningless and could do harm to your ski.

What technique did you use when you checked compression and what were the 4 cylinder numbers you got?

[Kevlarss]

Mr nitro remember I get 6psi at 4500 now I'm thinking ecu limits rpm. I do have a turbocharger pressure sensor TCP on the cooler, should I change it?

[NitroShark]

The ECU and TCP has nothing to do with your problem. That's why I ask you to test with the wastegate actuator disconnected. You should of got instant Full boost. You did not, so now the turbo or it's intake or discharge tracts are suspect.

As for the motor mechanical heath check answer what I ask--What technique did you use when you checked compression and what were the 4 separate cylinder PSI numbers you got?

[Kevlarss]

Removed all plugs pull fuel pump relay and got 174, 171, 168, 172

[jlfx car audio]

Kevlarss
Never rev ski out of water .
Stock ecu only allows ski to go to 6540 rpm anything past that is free floating ,free spinning and could and one day will bend a valve ...
As for your boost issue . I think you have a busted coupling in the intake track . there are 3 and any of the 3 could cause this issue . a small rip 1/2" long is all it takes .
It could possibly be the ic but that can be checked while you have it out checking the couplings .
As nitro said , just to confirm your test you unhooked the small 1/4" line from turbo outlet to wastegate actuator and ran on water ?
If that is what you did and only got 6psi. Not sure if you have ever ran ski with eat off ? If you you might even be able to hear the boost leak..

[Okin]

Hello, im having the same issues. In the water the ski wonÔÇÖt go above 4K rpm and my boost gauge is reading 0 but I can see the turbine spinning. Is there anything else I can do to diagnose this? Thanks