Questions and Answers

Runs Rough In The Summer Q. 1992 Buick Park Avenue, 3.8 liter V-6 SFI, Automatic Transmission, 144,000 miles, Fuel Injection, ABS (Self Adjusting) Brakes, P/S, A/C and Cruise Control.

When I bought the vehicle (used), I noticed that normal operating temperature was always about one quarter of the way up the temperature gauge instead of halfway up.

Now, during the Minnesota winter, again, normal operating temperature is never much more than ¼ of the way up the temperature dial, and the vehicle functions remarkably well.

When the temperature rises (eg. summer), normal operating temperature rises to about the middle of the temperature gauge- and now the vehicle begins to falter. It only falters in hot weather. It will feel , first of all, at very low speeds, as if the parking brake had suddenly become engaged (ie. it feels as if there is some kind of resistance to rolling). At the same time, the vehicle begins to shake and lose power. The entire vehicle shakes.

It functions wonderfully in winter , but horribly in summer. I've had it diagnosed and checked - mechanics say that they replaced the oxygen sensor and the thermostat, and that there is nothing else wrong with it - however it continues to present resistance and shake, starting at temperatures of 50° F +. The higher the temperature, the higher the operating temperature, and the worst it functions.

What is the problem?

A. You need to start by checking some basics. How's the fuel pressure? Condition of ignition system? Could it be the transmission?? A road test with a scan tool, fuel pressure gauge and transmission pressure gauge installed should help in greatly reducing diagnostic time and pinpoint the cause of the problem.

Additional Information provided courtesy of ALLDATA