I have a 2001 Toyota Echo. When pushing down on the accelerator, sometimes it won’t accelerate. It slows down, almost as if it’s going to shut down. I pump the gas pedal, and it’ll rev back up to move. It only does this when I’m stopped, like at a stop sign or stop light, and if it’s been sitting for any length of time. (e.g. in the garage over night, at my workplace all day, in a friend’s driveway for a few hours). A friend checked the battery, and it wasn’t snuggly fitted in place the way it should be, so he put extra bolts in to hold it in place good and tight. Before that, though, my car had been sitting for a month, and when I tried to jump it, it wouldn’t even turn over. That battery, though, is good and I just got it in Jan 2015. My friend also checked the alternator, and it’s also in good shape.
Is the Check Engine light on?
Tester
So the current problem is that the battery and charging system are known to be good, and it starts ok, hot or cold, but after a cold start it hesitates when accelerating from a stop? After you’ve been driving a while, and the engine is warm, does it do this hesitation thing too?
Just a guess, but when you press on the accelerator, that allows more air into the engine. The fuel injection system is supposed to respond reading the MAF sensor, realizing more air is coming in, and injecting more gasoline. So you could have a problem with the MAF sensor.
But that’s just a guess. And w/modern cars you can run out of money faster than you run out of guesses. So what Tester says is correct as the first course of action. Have a shop check the computer for any diagnostic trouble codes. You may find a code for a faulty MAF sensor, then you can check back here for recommendations what to do about it.
I think you may have a bad TPS (throttle position sensor). I would have that checked out.