Recap: I have a 92 Bonneville SE (non-supercharged 3800 engine). Pretty
good car, except that when it gets hot, it starts losing power. After
the car has been driven a while, and while actually under load (not
power-braking, not revving in neutral), the tach won't go above 3000 rpm
or so and bounces a few hundred RPM up and down.
"Hot" means the car has to be driven for an hour or so. The more time I
spend on surface rods and in heavy traffic, the worse it gets. Heavy
traffic especially makes the car malfunction.
When I'm experiencing the problem, the car lurches forward and backward,
and won't stop this behavior until I let off the accelerator. The
threshold RPM it does this at becomes increasingly lower the more I drive
it, eventually stopping me from maintaining speed up hills and merging
onto highways. The engine sounds like it's racing (but at variable speed)
while it's in this mode, but very little net acceleration is delivered.
This car is possessed. It turns out that there was a severe exhaust
restriction (the cat was plugged up). A mechanic finally got the car to
exhibit the problem while he had a diagnostic computer hooked up to it and
said the synchronizers (WTF?) were off, and concluded that the exhaust was
restricted. He replaced the catalytic converter; the car's surging problem
wasn't fixed, although it does have more power when it's cold (and thus
* Plug wires
* Air filter
* Catalytic converter(!)
Fuel pump relay
I had someone test the fuel pressure, finally. The results were a little
odd: 30psi, increasing to 35 with the accelerator wide-open,
but no higher. The needle also fluctuated slightly, maybe 5psi total,
while the engine was on, which was worrisome. The specs state that I
should have 40-47psi. Could this difference explain the problem?
One additional piece of information: the fuel pump relay is warm to the
touch. Is this normal?
How should I proceed from here? It seems now that it's either an ignition
problem or a fuel one, but I don't know which.
* Ignition control module could need replacement
Coil packs could be bad
* Fuel pump could be weak
Could have a blockage in the fuel line(but why would the car only buck
after an hour of driving?)
* Dirty fuel filter (just replaced a few months ago)
The exhaust restriction is gone, but now I'm worried that whatever caused
my catalytic converter to gunk up in the first place (fuel in the exhaust)
will destroy this one too.
Thanks a lot!