1991 Buick Park Avenue Ultra Problems

[sarotara]

Over the past few weeks I've ran into several problems with my '91 PA Ultra.

1) Engine coolant temperature does not exceed 110 on the dashboard display regardless of how long the car is driven.
2) The car vibrates in all gears at low (below 2000) rpm. With increasing rpms the vibration diminishes. There is also a loss of accelerating power. (Is the problem with the ignition coil or the spark plug wires?)
3) All of the inside heater/fan vents (except for the defogger) don't work. There is air coming from the defogger but it takes approximately 10-15 minutes for that air to become warm.
4) Horrible gas mileage (13-15 mpg).

Any help with fixing any of these problems would be greatly appreciated. Thanks!

[Cntrysthbst]

Vacuum? Sounds like a problem I had! I had a vacuum hose come off by the master cylinder. Hopefully someone else will reply to this, but till then maybe check your vacuum lines, listen for a hissing sound, make sure they aren't dry rot or craked, disconnected, etc., Good luck!

[Cntrysthbst]

Originally Posted by Cntrysthbst

Vacuum? Sounds like a problem I had! I had a vacuum hose come off by the master cylinder. Hopefully someone else will reply to this, but till then maybe check your vacuum lines, listen for a hissing sound, make sure they aren't dry rot or craked, disconnected, etc., Good luck!

temp gauge is a mistery unless its a bad sensor, faulty gauge, bad wiring, etc, don't know for sure but it doesn't hurt to check these until someone else with more knowledge replys! Maybe do a code scan on it as well, may tell ya something!

[sarotara]

5 out of 6 of the spark plug wires had white deposits on the metal surfaces. One of them was rusting on the inside. I replaced all the wires and the car runs a bit better now (there is no vibration) however... it now periodically surges when steadily accelerating.

[Loekee75]

Originally Posted by sarotara

5 out of 6 of the spark plug wires had white deposits on the metal surfaces. One of them was rusting on the inside. I replaced all the wires and the car runs a bit better now (there is no vibration) however... it now periodically surges when steadily accelerating.

Haynes Repair Manual- Vehicle surges while holding accelerator steady:
1)Intake air leak
2)Fuel pump faulty
3)Loose fuel injector harness connections
4)Defective ECM
Check out the first 3, I doubt the ECM has a problem. Also, did you replace your plugs when you changed the wires?

[HotZ28]

Originally Posted by sarotara

5 out of 6 of the spark plug wires had white deposits on the metal surfaces. One of them was rusting on the inside. I replaced all the wires and the car runs a bit better now (there is no vibration) however... it now periodically surges when steadily accelerating.

The plug that was rusting on the inside may not be firing due to a dead coil on that cylinder. Replace the coil.

[sarotara]

Originally Posted by sarotara

Over the past few weeks I've ran into several problems with my '91 PA Ultra.

1) Engine coolant temperature does not exceed 110 on the dashboard display regardless of how long the car is driven.
2) The car vibrates in all gears at low (below 2000) rpm. With increasing rpms the vibration diminishes. There is also a loss of accelerating power. (Is the problem with the ignition coil or the spark plug wires?)
3) All of the inside heater/fan vents (except for the defogger) don't work. There is air coming from the defogger but it takes approximately 10-15 minutes for that air to become warm.
4) Horrible gas mileage (13-15 mpg).

Any help with fixing any of these problems would be greatly appreciated. Thanks!

An update on the situation.
1) The problem was a faulty thermostat. Drained the cooling system, changed the thermostat, O-ring, and the gasket and used the orange (silicate-free) coolant (60/40 coolant/water mixture) to fill up the cooling system. Ran the car in idle for a bit while refilling the coolant reservoir and then drove it for a couple of miles and refilled the reservoir once again.
2) Changing the spark plug wires seems to have solved the problem. The vibrations disappeared and the surging acceleration problem diminished, but right now the car occasionally backfires once or twice when accelerating. Time to change the ignition coils?
3) Draining the cooling system and changing the thermostat partially fixed the problem as the heater warms up a lot faster now. However, the front air vents still don't work. Not sure what could be wrong with them.
4) I'll update what mpg I get once I drive the car for a while.