i have a 91 lx 302 with e303 cam gt40 heads cobra upper and lower intake 19 lbs injectors pro flow mass air bbk fuel pressure regulator full exaust 2 cat h pipe 355 gear now the problem at half throttle car runs great when under hard acceleration it breaks up and feels horriable i did a compression test today got 148 all the way around i have good oil pressure i have the fuel pressure set high because that the only way it runs good its set at 45
also i have the timing high at 18 deg car runs great now but i did this about a month ago it ran good for a couple of weeks and the started breaking up when it wanted so i pulled the plugs and changed them today set the timing again fuel press and compression test again today and its running good again any ideas what the problem could be please help

 

Have you ran codes???

 

maybe step up the injector size to 24lb?

 

are you running 18* base timing or tatal timing? either way your timing is way off

 

first let me say thanks to every one who responded i apreciate it

i have not ran any codes yet i just played with the fuel and timing should i run the codes ?

i was thinking of getting bigger injectors i think that would help because my injectors have to be working beyond there duty cycle

18 deg is base timing i know its high but thats the only way it runs right i played with it alot i know 18 is not right i just cant figure out why it needs so much fuel pressure and timing to run right the engine pulls hard to 6000 rpm no dead spots like this but my plugs get messed up quick

i do have an automatic computer in my car i thought that was the problem because i converted the car to a t5 and left the auto computer but i found out the auto computer is more agressive

thanks for the help guys

 

running excessive timing will cause detonation which could be why your plugs dont last. set the timing to 10* and then see what you get. you cant fix one problem by creating another one.

fuel pressure means nothing if your not at wot. you could set the fuel pressure to 60psi and at anything other then wot, the computer will see the extra fuel going into the motor and shorten the injector pulse width to lean the motor back out. so are you saying you need extra fuel pressure for it to run correctly at part throttle? because if you answer yes, its all in your head.

and run your codes. you can get a code reader at autozone for $35

 

i have a code reader in my desk drawer. it's called a paperclip.