high RPM boost prob

92redsc

Registered User
Ok when im in second gear up above 4000 rpms my boost gauge almost pegs the gauge, im getting like 14 1/2 psi. in 3rd i get like 13 and 4th like 11. this is wierd because my car is stock except removed air scilencer. also when i get up to high rpms my car feels like it loses all its power, but if i shift to the next gear(the rpms go down) and it comes back alive. until you get high rpms again. is this exhaust restrictions? somthings up i think unless the SC becomes half gutless in high rpms. also at idle my vac reads 15. i know it should be 19-20. boost leaks? then how would i get 14 and 1/2 psi top end? runs pretty good other than that. small oil leaks. i may have a blown head gasket though because i keep getting more oil on the stick even though i have oil leaks. but that may be a different story altogether.
 
Some ideas...

Improper 02 switching means poor part throttle performance.
And crappy economy.

If you have vacuum and boost leaks, there will be a reduction of engine efficiency. The computer is pulling in additional air than what is being measured by the MAF during vacuum conditions. This can lead to confusing the computer into thinking that you are running lean. So it'll jack up fuel.

At the stock or near stock power levels, the supercharger is known to flow excellent amounts of air even with several boost leaks. Check out Vernon's article in the sccoa FAQ's for further details. Get those vacuum/boost leaks sealed up.
 
i have good part throttle response and performance though. but in any case should i try boost leaks first and then 02 sensors or the other way around? i have checked and clamped all of the visible rubber hoses. not the intercooler tubes and the top collar etc. could my pcv valves be bad? how do you check those? i have clamped the hoses from the pcv valves though. and why is my stock SC putting out 14 1/2 psi? and are the intercooler tubes a likely leak point or are the hoses more likely?
 
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