This bulletin applies to 1996-2009 Isuzu Ascender 4WD vehicles. Issues may involve poor acceleration, detonation ping at idle in drive or reverse, and/or possible DTC P0101, P0106 and/or P0121 set in the PCM. The vehicle will perform properly after attaining a speed of about 30-40 mph.
The condition may also be described as a hesitation, stall when placing the transmission into gear, or a surge on acceleration (similar to a fuel cut-off or rev limiter). The ultimate cause may be a non-holding torque converter stator or damaged stator support shaft within the automatic transmission.
The IAC counts throttle angle and/or MAP voltage, and KPA should be compared to a like vehicle in park and in gear after reaching operating temperature. If the counts and map are high or throttle angle is open excessively in comparison, this may be a result of high engine load and a torque converter and/or stator shaft.
The transmission oil cooler outlet line should be checked for excessive heat. The Tech II scan tool may be helpful on vehicles equipped with the transmission fluid temperature sensor in the cooler line. On vehicles that do not have the temperature sensor in the cooler line, a temperature probe should be used to check temperature. The temperature readings should be compared to a like vehicle.
A stall test (brake torque) may point to a damaged torque converter. The stall rpm speed will be lower than a like vehicle.
If the torque converter stator or stator support is suspect, the transmission should be removed and the stator support should be inspected for spline damage. If the stator support splines are damaged, the transmission should be repaired and a new torque converter installed.