Intermittent acceleration problems...fuel pump?

[Orkin]

I've been experiencing intermittent (about 40% of the time) acceleration problems on my SHO. Usually when I step on the gas, it goes. But sometimes when I step on the gas, it's very sluggish, to the point that the transmission doesn't find it necessary to downshift, even at WOT.

Last night I replaced the O2 sensors because I hoped it would take care of my CEL with lean codes on both sensors, and maybe even this problem as well. Well, it cleared up the CEL, and I've noticed a decent performance boost( when it's working right), but it will still be very sluggish sometimes.

My question is, could this be a dying fuel pump causing this? The reason I ask is because my fuel pump whines alot sometimes, but is fine others. Wouldn't low fuel pressure cause this kind of performance loss? I'd check the fuel pressure, but a gauge costs ~$40, and if the problems intermittent there's no gauruntee I'd catch it when it's acting up.

Thanks for any input!

 

[masho95]

How old are the plugs and wires?

 

[Orkin]

I don't know, I bought the car 3k miles ago with no service records (I'm at 114k now).

 

[sdpatt]

If both oxygen sensors were showing a lean code the engine was very likely lean. That would be from either an errant sensor input (MAF, barometric pressure, etc.) or a vacuum leak. You may want to tell us what other codes you found so we can help. If you don't provide all the information, we can't give all the assistance that is requested.

 

[Orkin]

I was getting 172 and 176, but if it was really lean, then how come replacing the oxygen sensors fixed it? The old sensors were in pretty bad shape, and appeared to be the originals. I didn't tell you any other codes, because I didn't get any other codes...

The previous owner probably just ignored the CEL long enough for both sensors to go out (he told me he thought the CEL was on because it needed a tune-up).

 

[muzik]

If you have a noisey fuel pump and lean codes for both banks you may very easily have low fuel pressure.

 

[masho95]

If you suspect low fuel pressure, get a fuel pressure tester and check the pressure at the schreader valve on the fuel rail. If the car is of unknown service history there's a few things I'd do first. Get some electrical contact cleaner and remove the top of the airbox. Spray the clean on the MAF filaments to clean them up. Also I'd definitely change out those spark plugs and wires. Pull a spark plug wire from the front and check for oil in the spark plug wells. Just a few of the first things I would check/replace.

<small>[ September 21, 2003, 08:15 AM: Message edited by: masho95 ]</small>