9th Apr 2011, 17:33

How do I find out why my 2003 Buick Park Avenue Ultra will not work in overdrive? When it is scanned, it says that it is working.

12th Aug 2012, 20:05

Crank sensor may need to be changed.

23rd Oct 2013, 15:11

Check the fuel pressure regulator and crank position sensor.

24th Apr 2014, 17:19

Rented an Ultra once, covered 4000 miles. Have to say it was best car I've ever driven in the US, and on that trip I averaged 31 MPG, and I wasn't pussy footing around either. The supercharger was a revelation! Far superior to a turbocharger. Pity we never got these cars in the UK.

That 3.8 V6 supercharged Ultra was returning better MPG and performance than the 2.0 liter Volvo automatic I had at home. It could only manage 26 MPG with a tailwind!

3rd Aug 2014, 18:32

I have a 2000 Buick Park Avenue Ultra supercharged. It needs a new starter. Will the regular starter work for this, or do I need to get the starter for the supercharged model?

4th Aug 2014, 22:53

The supercharged engine requires a higher torque starter.

27th Feb 2015, 02:51

O2 sensors have shown to rob your car of a lot of MPG. Did you have a garage do the tune up? If it's someone who doesn't know what they're doing, they could have caused more harm, or you could have had a corrupt garage doing stuff to your car, so you go back for repairs?

Timing is important, did you use the right spark plugs? Did you get new wires, cap and rotor? Did you do the fuel filter? Dirty or clogged injectors could also be a problem, EGR valve, catalytic converter, fuel pump, transmission slipping, coil or coils. Did you see if they're pushing out the right amps?

Cheap gas is another one, and goes down to the tires you bought. So it could be a bunch of factors? Usually when I do a tune up, I replace everything, do a fuel filter, timing, clean the injectors there, change the oil and filter, and keep the same tires for that car. Tires also play an important role in MPG, not just the right air pressure.

1st Jul 2015, 08:17

Anything gas mileage that is within + or - 4% of the computer is within spec. The last 10% of the miles you put on the car before filling up can make a large difference in your results. Most people get gas in an urban setting, therefore the results can register lower than they would if the driver had not been in stop and go traffic.

And it sounds like you got bad gas. Anything done to the car that would result in that big of a gas mileage difference should feel noticeable while driving.