JDWalton

Hello all,
I am new to the fourms but would like to say thank you to anyone that can help or even takes the time to look for that matter. With that said:

98 Mustang GT
MAC Cold air fenderwell intake
Flowmaster Cat back exhusat
Short shifter

My problem I have is, in any gear if I mash the gas, right when my pony should be pushing its max power, all of a sudden it feels as if it is trying to putter out... throttle feels shaky, all around not good. It seems though that it is in a VERY definded RPM range though witch I do not understand.

It throttles up really well to about 4K RPM
4200 to about 4800 RPM, really really poor pickup, power drop offs, shaky
Stay on throttle to push through it and:
5000RPM to redline, picks up again, throttle response comes back, smooths out

The only thing to add to this is the car sat for over a year while I was deployed to Iraq, fresh high octane is in it with a bottle of Lucas fuel treatment.

04MustangGT

Did you dump the old fuel and add the high octane w/ fuel treatment or didboth sit in for a year ?

oxfordgt

If you didnt use a fuel stabilizer while you were playing in the sand then the fuel has water in it and needs to be drained. But since you already filled it it should run it all out. Just use regular gas (87) unless you are tuned and run some injector cleaner through it.

contentsunderpressur

+1 on the bad fuel. I just bought a car that sat up for a long time and had bad fuel and it did the same thing. I had to run two whole tanks of 93 through it before it straightend out.

JDWalton

I have run a few tanks of gas through it now and the problem persists. Plus, if it wer te fuel it would seem like it would be a problem across the board, but I am being affected in a specific range. Mine has a specific rang they stays consistant.

Also, I just brought it in to autozone and ran it on there programmer / scanner to see my codes. I had 4 codesthat I have seance cleared and havent come back yetbut here they are:

Bank 1 to Lean
Bank 1 to Rich
Bank 2 to Lean
Bank 2 to Rich

[sm=WTFsgign.gif]

I was not amused.........

Oh.... Also, I replaced the fuel filter last night, no signifagant change, today I am gonna clean my air filter and generaly just try to poke around some more to see if anything gives me any clues.

contentsunderpressur

How does the car idle? When it's messing up and you floor it does it still mess up or does it go? The TPS may have stuck. Try tapping on it while it's idleing.

JDWalton

Starts and idles perfectly, no issues at all. when I am in the rpm range while I have the problem, thr amount on throttle doesnt matter exept if I like downshift and it goes into that range and I am not giving it any gas (like if I were to downshift early going into a stop light). But if I were to step on the gas right then, it would start to "break up" again. You will have to excuse my noobism here... TPS?

JDWalton

Throttle position sensor?

yelw02GT

spark? sounds like fuel problem but IDK

contentsunderpressur

Yea, TPS=throttle positioning sensor. When they stick the car normally won't idle though. You might have a MAF problem. You need to get a fuel pressure gauge hooked up and check it with the car running and reving it.