help! breaking up at high RPM
help! breaking up at high RPM My car is all of the sudden running bad. It feels like it breaks up over 5k, but intermittently. Some info below for you guys to help me...
I recently put on an ASP pulley. I ataped immediately after and had ZERO knock retard. I have also thrown the A/C belt? It 'appears' to run true when the motor spins.
I have not over-revved by a flubbed shift. I have hit the rev limiter before, several times.
I have ataped and am getting ~ 3 degrees knock retard at WOT over 5k. I took off my MAFT and am running ~ 2 degrees knock retard. I haven't felt it do it since, but i also haven't driven a lot w/o it. It is running very rich w/o the MAFT. It ran ~.89-90 with the MAFT on.
Any thoughts or ideas would be wonderful.
Valve float (stock RPMS)? Bent Pushrod from NOT over-revving? Faulty MAFT? Again, it seems intermittent, and really only in 3rd or 4th gear, perhaps just because 1st and 2nd go by quickly.
__________________
SLP LT's w/ ORP
FTRA, Direct Flo Lid, Holley Powershot
Pace LS6 MAF Descreened, MAFT
02 ZO6 Clutch & hydraulics, drill mod
SLP Shifter
!tb coolant, cut egr tube
Mac SFC's
NGK TR-55's
Nitto Drag Radials
Granatelli LCA's
12.63 @ 112.2 mph 1.99 60'
I recently put on an ASP pulley. I ataped immediately after and had ZERO knock retard. I have also thrown the A/C belt? It 'appears' to run true when the motor spins.
I have not over-revved by a flubbed shift. I have hit the rev limiter before, several times.
I have ataped and am getting ~ 3 degrees knock retard at WOT over 5k. I took off my MAFT and am running ~ 2 degrees knock retard. I haven't felt it do it since, but i also haven't driven a lot w/o it. It is running very rich w/o the MAFT. It ran ~.89-90 with the MAFT on.
Any thoughts or ideas would be wonderful.
Valve float (stock RPMS)? Bent Pushrod from NOT over-revving? Faulty MAFT? Again, it seems intermittent, and really only in 3rd or 4th gear, perhaps just because 1st and 2nd go by quickly.
__________________
SLP LT's w/ ORP
FTRA, Direct Flo Lid, Holley Powershot
Pace LS6 MAF Descreened, MAFT
02 ZO6 Clutch & hydraulics, drill mod
SLP Shifter
!tb coolant, cut egr tube
Mac SFC's
NGK TR-55's
Nitto Drag Radials
Granatelli LCA's
12.63 @ 112.2 mph 1.99 60'
Re: help! breaking up at high RPM Well I get zero knock retard with my asp..dial up that maft a notch on wot..that should eliminate it assuming you are using premium fuel and its not something knocking under the car..ypipe etc..
That 3 degrees will cost some power.And you have autottap so go look at individual misfires..maybe you need plugs,wires..or some wire isnt on plug perfectly..and change fuel filter if you haven't for awhile..maybe run some injector cleaning stuff in there and if all that fails check your fuel pressure...a few misfires are normal on autotap at idle..my b1 cam gives some for sure but misfires should go to zero when you are under throttle ..if you have a lot of misfires and its one cylinder then check ,plug,wire,injector,coil.
And are you getting any codes with your autotap..
bad misfires will usually set a code..maybe you just have to gap your plugs down a bit more..they are supposed to be gapped down as horsepower increases.
That 3 degrees will cost some power.And you have autottap so go look at individual misfires..maybe you need plugs,wires..or some wire isnt on plug perfectly..and change fuel filter if you haven't for awhile..maybe run some injector cleaning stuff in there and if all that fails check your fuel pressure...a few misfires are normal on autotap at idle..my b1 cam gives some for sure but misfires should go to zero when you are under throttle ..if you have a lot of misfires and its one cylinder then check ,plug,wire,injector,coil.
And are you getting any codes with your autotap..
bad misfires will usually set a code..maybe you just have to gap your plugs down a bit more..they are supposed to be gapped down as horsepower increases.
Staging Lane
Joined: Jul 2002
Posts: 69
Likes: 0
From: Baton Rouge,Louisiana
Re: help! breaking up at high RPM You might want to take a valve cover off and make sure you don't have a busted valve spring.I have had the same kind of breakup and thats what was wrong with mine.
On The Tree
Joined: May 2002
Posts: 162
Likes: 0
From: Eau Claire, PA
Re: help! breaking up at high RPM This may not be the soltion at all...but its a shot in the dark. Last month my car was doing the same thing at WOT. I tried everything trying to fix it. I finally put a new fuel pressure regulator on...and the problem went away. Just a thought. Good luck!
Re: help! breaking up at high RPM i'm not so sure its the pulley. it ran fine after i installed it, and i ataped it and had zero knock retard.
no ses lights come on. could it be valve float? i think it is.
i did order the tr 224 and isky 295-d springs (i've seen 918's are starting to break?) pushrods and retainers. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> i'll do plugs (again) and wires at the same time.
no ses lights come on. could it be valve float? i think it is.
i did order the tr 224 and isky 295-d springs (i've seen 918's are starting to break?) pushrods and retainers. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> i'll do plugs (again) and wires at the same time.
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Re: help! breaking up at high RPM i *think* (hope) i've found the problem. the rubber bushing i use in between the y pipe and floor board had moved on me, and was banging (KR!). I put it back in place on the dyno today and it didn't break up at all, it pulled all the way to redline.
350 rwhp/363 rqtq 13.4 a/f (!)
Oh yeah a stock 02 ZO6 dynoed 356/348. MEAN.
350 rwhp/363 rqtq 13.4 a/f (!)
Oh yeah a stock 02 ZO6 dynoed 356/348. MEAN.
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