I have a 1999 subaru wagon with 246K miles. The car has been a dream,
> and has not had any problems other than a bad oil pump and normal
> maintenance. About 6 months ago the car was experiencing a loss of
> power and wouldn't accelerate when I pressed the gas. I thought it
> needed a tune up. After replacing spark plugs the problem persisted.
> My mechanic is at a loss. He puts in on the diagnostic computer and
> everything checks out okay. The problem has gotten really bad
> recently. If I floor the gas the car won't get above 1,500 rpm and
> sometimes it stalls out completely. If I "tap" the gas peddle I can
> get the rpms as high as I want.
>
> My mechanic performed all of the obvious test, replaced fuel filter,
> checked fuel injectors, check engine compression, checked the MAP
> sensor, replaced the oxygen sensor, replaced the ignition coil,
> replaced the timing belt. We cannot find the source of the problem. >
> I have been driving the car for the past six months with this problem,
> but it is getting progressively worse. Has any one experienced any
> thing similar. Next we are going to swap out the Mass Air flow Sensor.
> Beyond that, the only thing we can think of is the computer has a > problem.
>
> HELP!!!!
>
As expensive as it is, my money's on the MAF sensor. Since "reckoning" mixture is primary and the ECU relies very heavily on input from the MAF, MAF failures too often don't show up as trouble codes. The MAF's too important to be wrong! And the symptoms are not unusual for a bad MAF.
Mike