Loss of Power, backfiring - 1991 90 20vq sedan

[Brendan]

On Monday 14 July 2008, Huw Powell wrote:

These are always, always at 3400-3600 and feel almost like something 
doesn't "Catch".

> This may be irrelevant, but my 10v 90Q exhibits "dead zones", sometimes
> from cold starts on the highway, sometimes after stopping for a bit.
>
> I suspect knock sensor stupidity, but I can't prove it.  Perhaps it's
> just an issue of being 285000 miles old... aren't these things supposed
> to run forever?
>
> > Ok, I made it a few years without wasting bandwidth, so here goes:
> >
> > --- *Only* when in gear in driving ---
> > No matter what gear (but feels different in each gear), car will hit an
> > odd powerloss between 3400/3600 RPMs if accelerated slowly through that
> > band. If you rocket through, there is nearly no powerloss. This powerloss
> > keeps going unless you downshift and/or somehow accelerate quickly over
> > 4200 RPMs or so at which point, you feel the car drop out of wimpy and
> > back into Hefty. If you stay driving in what I think of as "power loss
> > mode", the car will backfire eventually.
> >
> > Been happening for years, but I have adjusted my manner of driving to
> > compensate, namely, I just speed all of the time.
> >
> > New parts since problem began:
> > timing belt, water pump, tensioner
> > plugs, cap, rotor, wires, air fuel filters
> > wheels, tranny/diff mounts
> > entire suspension
> > exhaust, o2 sensor, cat
> > shifter
> > MAF was gently washed with alcohol until clean, but not replaced
> >
> > Ideas? My mechanic and I are nearly out of them.
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