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11/01/2022 9:08 am
Topic starter
2004 Pontiac grand prix, non supercharged, 270,000 miles,
When on the highway at 70 mph with cruise control on it runs fine on the flat sections but when going up hills it sounds like it's misfiring, rpm fluctuates about 500 rpm. If I drive the same stretch without cruise control it runs fine.
No trouble lights, car starts first hit every time, runs and shifts fine, no problem.
2 Answers
2
11/01/2022 9:22 am
It could be so many things, but my guess would be the the electronic parts of cruise control system. You have a 18 years old Pontiac with 270,000 miles, it is expected that some electronics might not works as when the car was new.
1
11/01/2022 3:00 pm
if your cruise control system uses vacuum to actuate the throttle, then you likely have a vacuum leak
