2001 QX4 Shift hesitation 1-2 and flare 3-4 on light accelaration

[Tom S.]

My 01 QX4 has developed a hesitation when shifting from 1-2 and a shift flare from 3-4 only on light accelaration. If accelerated normally or quickly the hesitation or flare do not occur. The porblems only occur on very light acceleration and at 1600 rpm. It also does not occur when the engine/trans. are cool. When the car is first driven after sitting in the garage overnight and the temp. gauge is down the trans shifts normally. Within about a mile and when the temp gauge rises the shift problems occurs. The vehicle has 95,000 miles. Used as a daily driver. Mostly highway but some city miles. Never been used for towing. It has been serviced regularly including trans fluid change at about 75,000. Neither engine or trans show any codes. Throttle body, Throttle position sensor, O2 sensors, fuel filter have been replaced. Trans fluid shows full, is the right color and does not have a burned odor.

I took it to the Infinity dealer today and they could not find a code either. They suggest that it could be a faulty trans solinoid assembly and/or a transmission control module based on a TS bulletin on 2-3 shift flare, but do not have a suggestion of what it might be causing the hesitation when shifting from 1-2. The dealer also said that changing the solinoid and/or control module may not fix the problem and a new trans would be needed.

Before I proceed to spend many hundreds on the solinoid and/or control module just to find that the trans needs to be replaced I thought I would post to see if anyone else has had this problem in hopes that they would respond with a less expensive repair suggestion.

Any help is greatly appreciated.