I have a 2006 xB (auto trans) with < 14k miles on it and I am experiencing an odd hesitation from stops, meaning sometimes I will go to accelerate and the car barely moves (less than idle speeds). Here are a list of conditions at occurance :

Vehicle has reached operating temps (coolant light is off, shifting is standard)
Ambient outside temperature ranging from 75degF to 110degF
Several tanks of gas from different locations
No difference in throttle given at take off (from barely gassing it to wide open throttle)
No other malfunctions (CEL, Missfire, etc.)

Has anyone experienced anything similar before?

 

Have you checked the throttle cable? Maybe it's too loose.

 

you can also try cleaning out the TB take it apart 'n' all with some TB cleaner...

 

Injector cleaner time! And check your plugs for fouling after causing it to stumble a few times in a row if you can . . . that should foul the plugs enough to give an indication of what is going on. A while back some xB auto owners were complaining of really low power when taking off and no dealer could figure out what was going on. I think it may have been the VVTi not adjusting properly but they had that checked and said it was ok.

 

Mine's a manual, but it also does this sometimes and has done it since new. Seems to happen more often in the warm months. At first I thought it was the A/C kicking in at exactly the wrong time, but it does it without the A/C on. Two things to try: change out the plugs for one of iridium types and change your gasoline brand.

Of the 4 different major brands nearby, my xB seems to run the best on Shell gas. Between the gas brand and plugs, that eliminated the hesitation you described about 70% of the time. I've found that to almost completely eliminate it during the summer, I need to use premium gas.

 

The only time I saw a real problem with no power was when I turned the engine off at a red light then started it up and tried to take off. I had to keep riding the clutch and reving the engine to get it to move. If you hit the gas too quickly at low rpms like below 1000 rpm it may stall out - probably can't handle that inrush of air. Usually mine is a little too responsive and the wheels start spinning unless I have the steering wheel straight. If you are warmed up on a hot day sitting in traffic ther mey be something in the ECU to prevent engine knock when really hot air enteres the intake. AND you might try turning off your TRACKTION CONTROL since that cuts power to the engine if the front wheels start slipping. Both front tires have the same tread wear?

 

wow i have had this problem since i bought the car. and i evan had a new motor put in...water and intake not a good mix....but i still dont know what it is. i heard there is something in the ecu that makes it do this but i have not had any proof of this statement yet.

anyone know?

 

see if you can watch the live data on a scanner during the event. Look at the MAF readings, intake air temp, injector duration, and coolant temp. Sometimes a sensor can start to go bad, but not throw a CEL. I have an 06 with 14K, manual, but no such problem, and I doubt the TB or much else is very dirty.

My experience with a lot of MAF sensor cars, is this is the first sign before it goes bad, doesn't mean it has anything to do with yours (and definitely not for the ones that have had it since new).. but anyway, live data can answer a lot.

 

my car does the exact same thing. i hate it. I was getting horrible mpg too. After trying some things i found out it seems to run better on Chevron gas compared to what was my usual Shell. What really helped was a bottle of fuel injector cleaner. And i switched to full synthetic oil at the same time. Seems to be running mostly normal now. I still can't break 30mpg even highway driving. (avg. 80 mph on frwy) Good luck.

 

try to drive 15-20mph slower and see what you get...

 

Is it throwing you any trouble codes?