02 QX4 w/22K hesitates on hills

[graingertom]

My 02 QX4 has recently started hesitating at highway speeds especially on hills. It is felt as a jerking motion. No engine lights have come on and I can not tell if it is coming from the engine or drivetrain. Dealer says I need my fuel system cleaned ($100 not covered by warranty). This vehicle has only 22K miles on it. Can anyone offer any advice on what could be causing this problem?

Thanks-

[Q451990]

The dealership should run a full Consult diagnostic, including a power balance test to determine what needs to be done. The power balance test will indicate problems with injector clogging. At this point I can think of several things - torque convertor shift shock (lockup/unlock chatter), partially clogged fuel filter, knock sensor failure (unlikely), or any other number of things. Induction cleaning shouldn't be necessary at this point unless you have a lot more blow-by than you should.

Heath

[gbxk86a]

This also happens to my '93 Q45. The car now has 110,000 miles, but I remembered I complained that the transmission seemed to hesitate at around 22K too. When it goes uphill, it jerked (although mildly) and the car hesitated as if it could not make up its mind to shift or not. It tended to smooth out quickly if I gave it more gas (is it because the rpm is changed to make a more smooth transition in the transmission, I don't know). As I said, the hesitation was mild but it was irritating when you have a relative young car at 22K miles. I complained to the dealer, but they kept on telling me they could not find anything wrong.

I have settled and been driving with this characteristics for many years now. Once I got used to it, it does not bother me any more. I have flushed transmission oil, clean injectors (2 or 3 times already), changed spark plugs as routine maintenace but none of these maintenance seemed to change this characteristics at all. Whatever it is, it has not deteriorated after all these years and I learned to live with it.

[Q451990]

For the 93Q - check your knock sensors. I had this problem, and a bad KS harness was the problem...

Heath

[gbxk86a]

Questioni for Heath:

Thanks for your advise.Did your problem occur on going uphill too.Did it occur around certain speed range only. My problem occurs around 20-30 mph with transmission at "D" with normal easy driving.If it is the harness, then there is no need to take out the knock sensor then, right?If you check it yourself, how can you tell if it is the harness or the sensor itself? Any idea how much this is going to cost doing it yourslf? by the dealer?

Thank you in advance for your answers.