Valve Float at Higher RPM???

[Ryatt-Motion]

Tony, I am using 91, its all we got out here, and she seems to run the best on Mobil gas. I will ge the car to the exhaust shop as soon as I can and have them flip out my old Y-pipe and my O2 sensors.

Is checking the pushrods on these engines the same as an older style engine, where you just pull them out and roll them on a level surface?

[mustang muncher]

Originally Posted by Ryatt-Motion

Tony, I am using 91, its all we got out here, and she seems to run the best on Mobil gas. I will ge the car to the exhaust shop as soon as I can and have them flip out my old Y-pipe and my O2 sensors.

Is checking the pushrods on these engines the same as an older style engine, where you just pull them out and roll them on a level surface?

Yes...makes friends with some one with hptuners or the like and take it for a ride...and what year is it?...01 and 02 sound totally different from 98-00

[Ryatt-Motion]

Muncer, the car is a 2000 with an M6, with everything stock, right down to the LS-1 intake manifold.

[mustang muncher]

As far as the old 02s go...at WOT u dont run off of them, but they do set ur fuel trims...however if ur experienceing KR which would pull timing...then it can be as simple as loose exhaust or bad sensor or even bad balancer or power steering pulley causing vibrations that set off ur knock sensors.....Ur best bet is to data log it...so that u know if its KR or somehting else.

[Ryatt-Motion]

I have often thought my problem might be a bad balancer too, as mine looks pretty crunchy, but who knows. I know the car has had exhaust work done before from the dealer, because it was in the report on their computer when I took it there a few months ago. I have the wrong cats in it right now as they are magnaflow direct fit units that are 49 states legal, I have a set from a 2001 B4C that I am going to put on, and then attach my new 02 sensors to. I will also check the manifolds to make sure they are not cracked or anything.

[knightmarez28]

Yes, at that many miles, you need something a bit thicker to compensate for the wear, that'll reduce engine noise a little too. If you're getting excessive KR, very possible the sensor may be going bad and is recieving false-knock. Give us an update after the oil change (10w40) and the replacement of the o2 sensors and we'll go from there.. just so we can rule those out. Oh and one more thing, just incase, check the fuel pressure.. possibly not delivering enough fuel @ high rpm's unless you've already replaced it..

[Ryatt-Motion]

I have not replaced the fuel pump, it does not whine or anything. Can the fuel pressure be checked with a log as well, or do I need an external guage?

Thank you all too much for your help with this.

[pmr253]

Originally Posted by Ryatt-Motion

I have not replaced the fuel pump, it does not whine or anything. Can the fuel pressure be checked with a log as well, or do I need an external guage?

Thank you all too much for your help with this.

You have to look at the fuel pressure at the rail, there should be a shrader valve that you can screw a small mechanical gauge into. Stock LT1/LS1 fuel pressure regulators will hold fuel pressure once they are primed(something to do with emissions) and it should be in the 40's. Aftermarket regulators don't hold the fuel pressure if the pump isn't running.
If you could get that car on a dyno you can really see what is going on. Valve float is not to hard to see and you could be sure your car is making the power. You could also check the fuel pressure and see everything you needed in a data logger.

[Ryatt-Motion]

Thanks Mark, I will see if I can get the car on a dyno, I dont really know anyplace nearby with one, but I may have a trick up my sleeve.

[Ryatt-Motion]

Well, in light of everything else going on with the codes in the car, I have put in a new set of o2 sensors and the car is still pinging like crazy when I stand on the throttle. It almost feels as though she is running lean. I really need to find someone with a data log and find out what is going on with the car, this is totally getting ridiculous.