I think she's runnin lean

[Mada]

Alright, I asked about the car bucking and bogging down at high RPM's, and now I'm pretty sure that she is running really lean. I went to the drag strip tonight and ran .3 seconds slower than I was running stock (all my mods are below). So obviousally there is a problem. Then I got to thinking and I got well over 250 miles on half a tank of gas. Kinda a good and bad thing lol. And on my last run I heard a sound from the motor at the top of first. It sounded like a PING (metal on metal). Any tips on how to richen the mixture or ideas on fixing my problem(s).

[MrFroge]

I'm guessing at this point since you haven't analyzed your engines performance. But it sounds like you might benefit from a step up in octane (you have had some carbon build-up in the heads) and that you are the victim of heat soak now that summer is here.. Those long injen metal pipes can be a problem..:cover:

[pgtatx]

First off...drop that 65mm TB...there is no reason for it, and I guarantee you're losing power from it. Bigger is not always better.

What year and how many miles, and tranny???

Next bucking can be caused by many things. What year is your car? If it's a 2000+ than it could be fuel pump related, as many people get bucking when accelerating when the fuel pump is going. If you have an early 99 especially (or some 00's), do you get dimming lights or a battery light in the high end? This is the wonderful alternator problem, that the car would literally die in the high end.

How's your cat doing?? Any rotten egg smell?? As cats clog, in the high end you'll get very poor performance.

How are your plugs and wires doing? Also another thing that will caue a poor idle and poor acceleration.

If you are running lean, you'll get a CEL, plus I run relatively lean in the high end and make some very nice hp gains.

If you are getting actual "Ping" that's a bad thing, if it's a metal tap sound that'd the standard valvetrain tap...a good oil change can help it...

Hope that helps...

[Mada]

My car is a 2000 with 58k miles and it is an ATX. The lights don't dim and there is no rotton egg smell. I threw a CEL for a while autozone said it was a front bank O2 problem. They didn't say what the problem was, but the light hasn't came on for a while. The plugs are pretty good, I pulled a couple to see what they looked like. What should the fuel pressure be if everything is running correctly? I was going to autozone to get a fuel pressure meter, and realized that I don't know what it should be.

[eurocrisp]

The problem the Autozone guy was talking about is still there. I guarantee you he turned off the check light just so it wasnt annoying... The guy told you one of your oxygen sensors is failing. Theyre about $80 to replace, and are easy to do if you can get at them.

[OSUStallion]

Save yourself tons of time.

Bucking and Running Like crap at high RPMS and when you really step on the gas is one of the big signs your fuel pump is bad and it is not supplying enough fuel pressure. Its burned out and it just can pump as much fuel as it used to, so yeah your car runs lean.

Basically, i heard what people did is hook up an auto tap or OBD-II and measure your fuel pressure while your driving. When you step on the gas your fuel pressure should drop way down. Like is should be at 30 psi or something but its at 2 psi when your full throttle.

Tony

[TMoney]

I've got a 99 ATX and I just went through this same problem. Although most of my lean troubles we because of both an o2 and a bad UIM gasket. Both were replaced and it runs like a dream now. Also upon inspection, I guess my plugs need to be replaced, so those are going in next. I'd check those too. Don't mess with switching octanes.

[Mada]

So, could a bad o2 sensor be the cause of this problem, or is that just something else that happens to be worng with my car? I hooked up a fuel pressure gauge to my car and when the key is in the on position it was at 27psi I couldn't drive the car with it on because it was a hand held meter and no one wanted to ride on the hood while I drove. (joke) I'm gonna try to take her to the stealership tomorrow to see what they can tell me.