Someone want to tell me why in gear on an m6 car it hits rev limiter at 5000 rpms whereas in nuetral I can slowly rev it up to 6000? maybe the tach is slow but the car pulls all the way up to rev limit or when it does limit me. and I wonder if i am losing a bit of my high end.

 

ttt

 

Sounds like the tach probably lags behind. Most of the time your not spending too much time at the rev limiter to let it catch up, but if it revs up to 6k in neutral it should be fine..

 

Does it do it in all gears? Most of the tachs respond too quickly, indicating an RPM about 200 higher than actual.... I know mine did.

Are you sure it isn't just misfiring or floating the valves?

 

pretty sure its not a misfire or valve float. does it in 1st thru 3rd for sure. opti has 10k miles so it shouldnt be bad. revs fine in neutral. could it be the fuel filter causing a loss of pressure at high rpm on heavy accel?

 

What exactly does it feel like? The stock rev limiter completely cuts fuel with a "bang".... its not the gradual loss of power you might see with a random spark or fuel cut.

 

If it is a spark related problem, you can't compare when the engine is under a load and revving it in neutral. I would not be sitting and revving the car that high, anyway.
Was that a brand new GM opti you put on there?

 

yes it was. I dont make any habit of free revving a high mileage motor it was merely for diagnosis purposes.

 

my car does the same...and it isnt constant...only sometimes...when i listen under the hood..there is a ticking noise on the left side of the engine....it is also running very rich...could this be a valve sticking? burnt valve?