M8 Major Studder - Help !

[Hangtime]

07 M8 All Stock . Have a friend with same sled, so have been swapping parts . From idle to half throttle all is fine. The upper half is another story , studders real bad and lack of power.


Here's what we've checked or swapped

ECU
CCU
Power valves, clean & Tested
Fuel pump
Checked injector screens
Tested TPS
Exhaust sensor
Looked at stator , may swap this next.
Checked out air box .
Tested coolant sensor - seems normal
swapped knock sensor

I should have just swapped his Hood ! Where should I look next ??!



Hangtime

 

[high time]

I can help...........

Keep this post on top anyway.

Did I here you say the studder is under heavy throttle, but so much at a RPM. point?

Owen

 

[Hangtime]

m8

When running the mountain weights Rpm would go to 8000 at half throttle , so doesm't seem to be RPM related . I don't believe it's due to a heavy load, testing going down a hard pack trail .

Open to any ideas ...


Thanks

 

[diggerdown]

If you have an after-market can on it....can it!

 

[Hangtime]

m8

Already did , went back to stock set up ....

 

[diggerdown]

Do you have a fuel pressure guage that you could watch as you accelerate?

 

[darrick]

Do you have a fuel pressure guage that you could watch as you accelerate?

I had the same problem....I have an 05 M7 with an MBRP can on it. I did exactly the same thing! The reason it does this is because there is to much fuel pressure and its loading up. My fix was a fuel pressure regulator. You put it in the main fuel line from the tank to the fuel rail. The magic number i found was about 42 PSI but thats for the 700. Hope it helps!

 

[Hangtime]

M8

Put it on the stand wide open 42# I do have the inline kit. I do not have the jet in it to reduce the flow, figured it ran good once so I didn't want to change things .

Have a stator coming , will try that on Friday ...

Thanks Hangtime

 

[Hangtime]

M8

Thanks goes out to some friends at the Cat Factory ! It was the Stator !


Hangtime