Jim Grant's Tech Tips
'98 Buick Park Ave, No Performance Warm
I have what I will
call a low end performance problem with a 98 Buick Park Ave, in
that the car loses pep and pick up once fully warmed up (185F and above).
I have had it to a maintenance shop (ASE certified) for loss of coolant
and it was determined that the upper intake manifold was cracked and allowing
fluids to enter the engine , the engine was scoped and nothing showed.
I later returned and the engine was scoped , indicating that the Mass
Air Flow Sensor was bad. It was replaced and within one week I was experiencing
the problem again. I have also changed the coolant sensor, idle air valve
and the O2 sensors. Once the car is fully warmed up it has no pickup and
The intake manifold
problem you described is a common occurrence on this particular engine
design. If the O2 sensors were replaced before the leak in the intake
manifold was found you might have to replace them again. O2 sensors are
easily contaminated by the chemicals found in anti-freeze. The anti-freeze
can coat the sensor and cloud the information it provides to the computer.
You stated that the Mass Air Flow sensor was replaced and the problem
returned a week or so later. You may just have a defective Mass Air Flow
sensor, it does happen. We had one vehicle in the shop that was diagnosed
with a bad Mass Air Flow sensor and a replacement was installed. The problem
was the engine ran worse with the new part! It happens more than you could
image. Just because it is new doesnt mean it isnt broken.
Start over with the diagnosis, youll likely find that the cause
may have been overlooked.