08 m8 only pulls 7000rpm help please!!!!

[machinest660]

my buddies stock 08 m8 is only pulling 7000rpm rpm, we checked the eghaust valves they were good. he is running 73 gr weights at about 8000 feet. clutches are all clean and run nothing but premium fuel. could it be a faulty o2 sesor but there is no alarm or code that shows up. any a ideas would be great thanks.

 

[SaberKitty]

First, if the engine and pipe is stock, run 87 octane for BETTER performance and running quality.

There's no O2 sensor on a M8; the sensor in the pipe is exhaust temp.

Check the spring in the primary for a broken coil.

 

[Frostbite]

Doesn't 73 grams at 8,000 feet sound a bit on the heavy side for a stock M8?

What secondary and primary spring is he running?

 

[0neoldfart]

70 gram weights required

You need to lighten the weights in the primary - either 70g or perhaps even 68's - depends on your pipe setup (target rpm) Seems to me the 08 M8 spins around 7500 RPM, 8000 if you are running an aftermarket single.

 

[RACINSTATION]

70 gram weights at 8000 feet.

A good 130-310 ish spring in primary and make sure your weight pin nuts are not too tight.

List any mods if he has them as that could be a factor

 

[machinest660]

the cluthing is all stock and so is the motor. the springs are all good when we cleaned the cluthes about 100 miles ago, we will try 87 octane fuel after tomorow and try lighter weights to

 

[Frostbite]

Yes, the 73s are too heavy.

I was using 73 gram Cat weights at 6,000 feet with a SLP pipe and pulling 8,000-8,100 last spring.

I agree 68 or 70 gram will be the answer.

 

[ripsass]

First, if the engine and pipe is stock, run 87 octane for BETTER performance and running quality.

There's no O2 sensor on a M8; the sensor in the pipe is exhaust temp.

Check the spring in the primary for a broken coil.

What he said. All of it.

 

[SaberKitty]

The stock 73 gram weights were not heavy enough for my stock M8 at 9-12k'. For 8k', something else is wrong or there is an aftermarket mod screwing things up...I know, inconceivable that would ever happen.

 

[machinest660]

All stock just a can.

 

[dmkhnr]

It will have no problems pulling 73# at that elevation, but if your going higher then 70# would be better.
#1 check for a glazed belt.
#2 check your belt deflection.
#3 check for flat rollers in the secondary.
#4 check spring
#5 check powervalves

 

[SaberKitty]

And from personal experience, check the 15 amp fuse that is in the little black holder near the CCU (chassis control unit). If that fuse popped, the power valves won't open as rpm goes up.

 

[machinest660]

today he put in 69g weights and pulled 7900rpm all day long. thanks for all the posts