speed76demon

All i want is a fast car that runs good throughout all rpm's what do i have a fast car that runs good up until it really matters in the higher rpm's. I have no idea what is wrong with it i am puttin way to much money into this car for me to be going off to college this fall i have no idea what i'm going to do. I've replaced waterpump, opti,coil,02's,wires,plugs, checked MAF and i still have no idea what my problem is starts like sputtering or missing from 5k on then when it shifts it runs sweet again but hits the problem once it gets back up to 4500-5000rpm's. My car feels so strong up until this point. I'm thinking maybe the ignition module, or IAC, but have no clue and can not afford another part that doesnt fix my problem all the other parts did help just didnt solve. I just hope it's not the fuel pump

Josh-'04 GTO

It's easy to check the fuel pump. Just get a fuel pressure guage with an 18" long hose or so. Hook it up to the schrader valve and tape the dial to the windshield. Take it out for a run and watch the dial. I don't remember the exact numbers, but I believe about 38-40 psi at WOT means the fuel pump is keeping up. I believe Fred gave the numbers a week or two ago, try a search.

slashz28

i did a search on this topic last week, cause mine does it "sometimes" as well, and came to the conclusion of:

1)coil
2) coil wire
3)fuel pump

most likely #1 or 2 or both i got backups but was just too lazy to swap em hth

93formula

might be spark blow out? have you tried a msd or similar unit?

revtime

Now you know why almost all of the highly modded guys have beaters.
I have a moderately modded car and I have a beater to get me back and forth when the camaro breaks, notice I said when not if.
This is what you get into when you have more than a CAI and a catback, for the most part heavily modded cars are not as reliable as stock or mostly stock cars.
This is the nature of the beast.
If you need a reliable vehicle for college then you need to buy something like a cavalier or in my case a 92 sunbird I picked up dirt cheap and it runs great.

To try and help with the problem, I would hook up a fuel pressure guage and make sure your fuel delivery is not the culprit, that is my next thing to see why my car did not gain any trap speed with the LTs, after that I am gonna have to go after the opti.

frmula1

MAN.... that SUCKS if i spent all that money on parts... and it didn't help my problem...

i would seriously hang myself

94FBODY

My car has the same problem.. once i hit 4500-5000rpm the car doesnt shift into the next gear it just gets stuck and makes a bunch of popping noises. I have been trying to get it fixed.. i thought it was a losse of fuel in the higer rpm. I changed my fuel filter and that dident help. I was wondering, do you have a strong gas smell once this starts happening? because my car runs fine until it starts to warm up and then i smell gas and the problem starts.

frmula1

maybe you have a leak in your fuel lines dude...

either that or you have a spark problem... which is very possible