2005 Buick Park Avenue hesitation

2005 BUICK PARK AVENUE
107,000 MILES • 6 CYL • 2WD • AUTOMATIC
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GHWHITE1937
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For the past 8 monhs my car has been hesitating when going up hill at 50 - 60 mph. It runs fine on level road or down hill.

The rpm indicator bounces between 1,500 and 2,000.

If I step down on the gas pedal, it has good pick-up and no hesitation. The problem happens when I have relatively even pressure on the gas pedal.

It only does this when in gear, and runs smoothly when in neutral.

The car had this problem before the 100,000 tune-up, and still does after the tune-up.
Mar 16, 2010 at 8:32 AM
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JACOBANDNICKOLAS
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Have you checked for vacuum leaks? Is the check engine light on? Has fuel pressure been checked?
Mar 17, 2010 at 1:44 PM
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GHWHITE1937
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The is no engine light. If there had been an engine light, I would have mentioned it.

I would think that fuel pump pressure would manifest itself when accelerating, and not only on inclines. Is that correct?

My first thought was the fuel pump; but, after 8 months, I would wonder why it hasn't gotten any worse.
Mar 18, 2010 at 10:04 AM
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JACOBANDNICKOLAS
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Yes and no. Over a longer incline, the pump is required to produce more. However, it could do it on acceleration too, but not always.

Regardless, you seem to feel as if it is ignition related, which I trust because you drive the car. Without a check engine light it becomes a guessing game. If it only happens under a load and on inclines, It could be a crank sensor, plugged EGR, injector... Have any of them been checked?
Mar 18, 2010 at 1:36 PM
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GHWHITE1937
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Thanks, I have not had those things checked out. I will do so.

Thanks again.
Mar 18, 2010 at 1:42 PM
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JACOBANDNICKOLAS
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Let me know what you find.

Take care,
Joe
Mar 18, 2010 at 10:25 PM