Ok car is a 2001 SS 6spd, it runs amazing all the way to roughly 4500rpm then I get horrible valve clatter. (well what sounds like valve clatter) Im replacing the valve springs tomorrow morning to rule those out, but I had several people tell me that the valve springs in these cars do not typically wear out, especially since I "only" have 92k miles.

Ive used octane booster to try and see if that would rule out detonation or a mechanical issue, but since it only raises the octane from 93 to 93.3 im not to sure it did much. If the valve springs dont fix the problem im going to stick some c10 or something and try again.

Any other possiblities here? Knock sensor, tuning issues? The car only has plug wires, catback, lid and harmonic balancer.

*Also on a few occasions, trying to run it past 5k-5500 has resulted in the car falling on its face and the check engine light coming on flashing then staying on for a little.

Thanks!

 

Is the car stock? I would start small and work my way from there. Dirty fuel filter, Pump going out, dirty injectors, clogged cats, O2 sensors, etc..........

 

like mentioned above do your basic checks. to me it sounds like you have a fuel issue. what dtcs are you getting?

 

Check all your grounds, especially the one on the back of the heads

 

sounds like fuel issue if its failling on its face at some rpm. I had a friend put a turbo on his car(so eclipse looking thing) and it ran out fuel in the at higher rpm and it did that. I dont see that being very good at all for your motor.

 

Like I said the car is pretty much stock. Cat-Back, Lid, plug wires and harmonic balancer. I dont think its the fuel pump because it would have gone out a long time ago, its been doing this for some time now. Could very well be the cats clogged up. If it were a ground, wouldnt it affect me at all rpms? Or are yall saying that the fuel pump is not getting enough voltage at the higher rpms?

I dont have a scanner or w/e so I dont have any dtcs

It seems like ive had the car hooked up to a scanner before ( dont know what kind ) and it was showing misfires in every cylinder at idle.. so possibly injectors again?

Bout to head over to the shop to changed the valve springs... this is going to be fun!!! lol

 

Check the fuel filter. Could be pump, but I'd check the filter first. Happened to me at the track one day. Below 4000rpm, great. Above 4500, sputtering and bucking.

 

It's not unusual to see some crazy valvetrain instability/float in the high RPM's even with stock camshaft with the stock springs.

 

Thanks guys for all the replys, I figured out half the battle... My freakin aftermarket harmonic balancer was falling apart! There is still a tiny bit of valve clatter, but nothing I am worried about. Ran the car up to 5500 today with no problems Feels good hearing it scream again. Gonna stick the C16 in tomorrow to confirm that the rest of the noise is a mechanic valve clatter issue and not electronic/fuel issue. Maybe ill hit 6k

 

Please don't run that gas in your stock car. It will do more harm than good.

 

haha, c16 huh? That's not gonna work to well in your car. Change the fuel filter, plugs and hook it up to a scanner to see what it's doing.