I have a 2000 Toyota Sienna SE with 156000 miles. Automatic trans. Recently it started running rough and stuttering when my wife accelerates from dead stop such as when trying to get across an intersection in a hurry. It quickly recovers and runs fine after the initial hesitation. I drove it myself, and from a dead stop if I floored the accelerator, it would hesitate and sometimes I would hear a pop somewhat like a backfire.
We thought it might be bad gas because she got gas from a place she does not usually go to. It improved somewhat over several days, again making us wonder if it was bad gas, but it continues to hesitate from a dead stop. I took it to my mechanic who is a former Toyota dealership mechanic who has been working on my Toyotas for years.
He kept it and drove it for several days, noticed the hesitation, scanned it for codes, but found none. He ended up telling me that he had no idea where to start since it was not throwing any codes, and I would have to drive it until it did. Do you have any idea how to diagnose the problem without codes?
Did it only start doing this after that bad tank of gas? If it’s been doing it for a while, the transmission may be starting to wear out a little, especially if the hesitation only happens when you accelerate hard.
It is the engine itself that runns bad.
Change the fuel filter, pressure test the fuel pump & take it from there.
I will ask my mechanic to try that.