This is the next episode of the "herky-Jerky" problem with our 95 Park
Briefly, the car sort of loses power momentarily, making the car do
what I call the herky-jerky. This is an intermittent thing,
mostly at freeway speeds... 60-70 mph. I believe it is an engine
causing the torque converter clutch (TCC) to engage/disengage, thus
effect at the wheels. Throughout all of this (several months now) the
Check Engine light never came on UNTIL
TWO DAYS AGO. Read on...
Here's what's been done so far:
Plugs and secondary wires replaced. Did this myself. This gave
immediate improvement, but the problem
returned and worsened a couple weeks later. Discovered one of the new
plugs had stopped firing.
Replaced it, with immediate positive effects.
Air Mass Flow sensor replaced. This was done when the problem returned
after the bad plug was replaced.
No effect at all.
Took the car to a GM dealer where they supposedly had "all the right
diagnostic equipment." Wrong. They
found nothing for $88.
Back at the independent garage, fuel filter and pressure regulator
replaced. This was done after testing rail pressure. I checked it at
getting a reading of 34 PSI. I was advised here (and by my garage)
that 41-47 was normal. I thought this fixed the problem
because we did not experience the problem for a few days.
Then two days ago it started doing it again
on the freeway. I now suspect the fuel pressure thing was a red
herring, as a careful reading of AllData (which
I finally subscribed to for $25) I see that the 41-47 pressure is the
correct range after
letting the pump run a few seconds by turning the ignition on but NOT
starting the engine. At idle, it can be
6-10 PSI less and still be in spec. So, there was probably nothing
wrong with the regulator. The reason I
thought the problem was fixed was we had not been doing any freeway
driving. BTW, the problem might
not happen until 10-15 miles of driving, so when the techs drive it
they are quick to proclaim "it's OK."
Now the new development. The same day that we had the freeway
herky-jerky we went out to dinner
in the evening. Right after backing out of the garage, the Check
Engine light came on. Don't think it had
ever happened before, as we both said "What's that?" It went off for
a bit on the way to the restaurant,
then cam back on and stayed on. Next morning I took it back to the
garage, light on most of the way.
The tech called after a bit and said it was a 171 error, Lean Running
condition. Later in the day he called
to say it was fixed, the problem being the O2 sensor wire too close to
a spark plug wire. Unfortunately,
the light came back on before we got home. Today, it's back in the
shop, with the tech working his way
down the diagnostic chart I suppose.
Two more things: (1) the Traction Off light also comes on
occasionally. (2) the heater/AC is doing
crazy things, i.e., hot air out the passenger side vents, cold out the
I used to think my '76 Jaguar V12 was a problem car... weird things
going wrong that no one could
diagnose. After retiring I started doing my own maintenance on it
(well, some of it anyway),
and now think it's all pretty straightforward. I'm proud to say that
on our way to recover the
Park Ave from the garage my wife commented "this thing is running
pretty good, isn't it?"
Maybe one day I'll discover the Park Ave is straightforward too, but
at this point it's hard to imagine.
Any further suggestions will be appreciated, and thanks for listening.