FocusVince

Well my never ending saga of trying to find out why my car lacks any high end power drags on...
The car starts up quickly and idles great. I checked the fuel pressure and its normal. I don't get a high rpm miss at all. It just lacks power, past 4000 rpm is just slowly creeps up and the car doesn't accelerate very quickly. I have to shift into 3rd in order to reach 60 mph.
I have a very bad exhaust leak at my manifolds (stock) but at WOT I understand the car doesn't use the o2 sensors, so that can't be it. I'm replacing the manifolds with long tubes soon so that will be fixed.
Could it be valve float? The engine has 174000 miles on it and runs perfect other than this, I have a feeling it could be the valve springs. It doesn't hit a "rev limiter" so to speak, the rpms just slowly climb.
Sorry for the novel, I just want to know what could be causing this. Other than that it runs fine.

96LT1355Z28

iTrader: (2)

I'd look into the valve springs, I believe there's a tool that can check them on the car but I could be mistaken. With 147K it wouldn't hurt to throw some springs on it anyway.

355z28

iTrader: (8)

Does it still have a cat. converter? Id take some exhaust temps before and after. If ones plugged it will run normal down load but will lack power.

FocusVince

No cat converter, so that's not it. I'm going to look into the valve springs soon..

FocusVince

Could it also be false knock because of the exhaust leak? Its pretty loud and I was wondering if that would cause the car the pull timing..

ahritchie

iTrader: (1)

Your exhaust leak is probably making your car run rich as hell 95% of the time due to the false lean condition with all that O2 in your exhaust...probably fouled your plugs. Had a similar issue on my car, changed plugs and gained over 70 WHP. Fix your exhaust leak and change plugs and wires.

96capricemgr

iTrader: (1)

At WOT the O2s are not used BUT if at cruise the O2s were reporting a lean condition as they likely are with an exhaust leak the pcm does add fuel to combat what it believes was a lean condition reported at cruise.

The pcm will not take away fuel at WOT based on cruise O2 input but it will add it because a true lean condition could otherwise damage the engine.

FocusVince

That makes sense...well the exhaust leak will be gone as soon as the headers come and I install them.
But I was also wondering if the leak could cause any false knock. Could that also be a factor?

96capricemgr

iTrader: (1)

yes it could be

FocusVince

alright, well I'll see what happens
thanks for all the help!