Car problem at 40-50 mph

[qprint]

04 V6 LE VVT-i. When reaching 40 mph, I feel a hesitation or stumble or miss from my seat, until l reach 50 mph and then it drives smoothly. I had a tire replaced on the Passenger rear a month ago and I don't know if this could be it or is it a fuel issue. I checked my plugs to be OK, cleaned my air filter and air box. I can't find my fuel filter to check that. I brought the car to a Toyota dealer and a mechanic drive tested it and didnt notice it until afterwards but couldnt give me an answer and told me to return it another day for the Shop Foreman to test drive it. Can I get some feedback from you guys.

[qprint]

OK, I went to dealer and shop foreman drove the car and found a slight stumble and suggested both rear tires balance and both wheel runout test. Afterwards he found the right rear tire needing balancing 0.5 and the left rear tire was OK. Both wheels runout test were fine. The tire they balanced was replaced new by another Toyota dealer a month ago where I bought the car, so therefore; they didnt balance correctly. I drove the car home and found the same stumble. No change since whatsoever. Im going shouting tomorrow.

[qprint]

Dealer will try switching all wheels and tires to see if shaking still occurs.

[92Pony]

I just visited my local dealer with our '04LE (2.4l) for something very similar. Right at 46-48mph, I get a slight surging that felt like it was coming through the driveline.

The dealer tech diagnosed it, and supposedly they got on the phone with Toyota who confirmed the diagnosis as a "lean-surge". They said it was "common" and "normal", and recommended $150 worth of top-engine cleaning. Right at 1600rpm, the fuel mixture is getting lean, and the O2s call for it to be richened, and that goes back and forth - that's how it was explained to me. I protested that that shouldn't be "normal" and that Toyota needs to address that and make it so that "normal" is a smooth-running engine at all rpms....my protesting didn't do much.


Wade

[qprint]

fixed: rear tire had a bad belt. replaced tires with Yokoham TRZ and smooth all the way