vcolfari

I recently purchased a used 2007 IS 250 with automatic/RWD. The car has a problem with unpredictable shifting, particularly from a stop to 1st and 2nd gear or when rolling to a stop and stepping on the gas again. At times, the shifting is very smooth, even as soon as I start driving the car when it's cold in the morning. Other times, there is a brief hesitation when I step on the gas and acceleration is momentarily delayed. I find myself feathering the gas what seems to be an unreasonable amount because I don’t know how it’s going to respond.

There are no codes coming back and I have already tried replacing spark plugs and intake gasket, transmission fluid exchange, fuel system service (cleaning throttle body, intake, valves and chemical cleaning of injectors with 44k fuel additive, and throttle body cleaning kit with 208, 44k, and 210 intake cleaner), air filter replacement, synthetic oil change.

I believe my mechanic considered the throttle sensor as a potential contributor, but I’m not sure if there’s a way to know if it’s “bad” if there are no codes. I'm hoping this is not a situation of “this is the nature of the beast and a problem that Lexus had to address in subsequent years.”

Gville350

iTrader: (10)

Try this free "fix" first. Disconnect the battery for 20 minutes, then reconnect, then immediately go out and drive the car how you'd want the car to perform/shift on a daily basis. This way your car is forced to re-learn YOUR shift points and YOUR driving style. Worth trying out since it's basically a free fix. If it helps...great! If not, nothing out of your pocket.