Strange problem

[Daz RXT]

Hi all, wondered if anyone can help me with the following problems im having:
Revs have dropped on my RXT05 With x-charger, xs intercooler, walbro Gss342 fuel pump, rrfpr 42's.
They have dropped to approx 6500rpm and when i try going WOT after 5seconds hi-temp alarm appears with long beep and then flashes MAINT.

I have checked the obvious things:
Supercharger washers/Slip is ok approx 12.5N/M
Compression ok in all pots 144,137,138
pressure tested intercooler and is fine
Checked for boost leaks all ok
Swapped out the coils for known good ones
Changed the fuel pump for another walbro Gss342
Pump/wear ring all ok
Coolant level ok and clean
Oil not creamy
Plugged into BUDs system and no fault codes shown also shut down each cylinder down individually and all ok with intake pressure all normal?
Runs ok on hose


???????????????????????
There is a small amount of oil in the bottom of the hull but am guessing this was when i removed the charger??
I am stuffed for any more ideas,or what to do next, would be very gratefull if anyone could assist thanks.

[sea-one]

i'd change the exhaust temp sensor located on the waterbox

[masta2000]

+1

[Danny]

What ECU, stock? What is your RRFPR set to? The fuel pump a larger capacity than the stocker?

If so, the pump is pushing more fuel, and when the boost kicks in, it dumps more. You might have to drop your pressure...Check to see if there is any water flow issues, like a plugged line.

[Daz RXT]

Yep its a stock ECU and used to turn 8100rpm, The walbro one is an uprated one due to the standard fuel pump not being able to keep up with the demand.I have been running 62PSI that raises to 72ish PSI for about a year and set up was running perfectly as fuel to air mix was good.

Would a faulty exhaust sensor cause a drop in RPM? thanks for your replies

[R88ory RXP]

What ECU, stock? What is your RRFPR set to? The fuel pump a larger capacity than the stocker?

If so, the pump is pushing more fuel, and when the boost kicks in, it dumps more. You might have to drop your pressure...Check to see if there is any water flow issues, like a plugged line.

Its stock ECU with RRFPR set to aroud 64 base and then around 71psi on full boost. Walbro pump as his fuel press wernt rising with the stocker.

I have basic same setup on my ski and with 72-3psi fuel I have 11.5-7 afr although Daz has not tested his we ride in same exact place so figued he is safe with same fuel press as me.

The only thing I can think is that 1 of his water lines is blocked some how and this means the intercooler is not flowing any water causing hot intake charge followed then by the high temp due to no water to exhaust. R88

[R88ory RXP]

Soz Daz thought I would answer for you. R88

[R88ory RXP]

Daz def check the water hoses. Just thinkin that it wouldnt show on the hose coz hose water goes to exhaust first I would unscrew your strainer on the hose and see if any water is flowing out. This would explain the low RPM due to very high intake temps and also the high temp coz of no water in exhaust. R88

[Daz RXT]

just double checked all the intercooler lines and they are free, also changed out the exhaust box sensor and coolent engine temp sensor and didnt make any differance?????
What shall i do next i need some expert advice please.

[RXP305]

just double checked all the intercooler lines and they are free, also changed out the exhaust box sensor and coolent engine temp sensor and didnt make any differance?????
What shall i do next i need some expert advice please.

Have you remove the J-pipe from the waterbox by anychance?