INTRO
Hi all, I have an ES300, and ever since I got it, the engine starts bucking when it has been running for a while and/or I floor it.
THE PROBLEM
What specifically happens is when I accelerate, before it shifts into second or third, (it only seems to have problems with these gears) the RPMs spike to 5,500 to 6,000, the car slows way down, the engine seems to buck (it feels like I hit a speed bump going about 30mph).
POSSIBLE COINCIDENCE
The bank 2 (front) catalytic converter code starts to show whenever this happens. I don't know if this is a coincidence, but it's frustrating. I see the problem isn't the catalytic converter because I bought a new one and put it on, and it didn't fix the problem, so I cleaned the old cat and put it back on. after that, the code for the catalytic converter didn't come back on for a while.
WHAT THE MECHANIC SAID
The mechanic said that it was most likely either the transmission or the catalytic converter. I mentioned knock sensors but he said that he has never had a knock sensor not throw a code when it died.
WHAT I DID
My friend had the same problem in his ES300 that was from the previous generation, and he said that they replaced the knock sensors and fixed the problem, even though the dealership told them it was the transmission. So I replaced the knock sensors and all the gaskets we took off in the process.
THE FIX
It seemed to work, I took it on the freeway and kept flooring it to get the engine hot, and it didn't buck when I had previously tested it, and it failed, with the new catalytic converter. So to make sure, I took a drive that was pretty much the same drive I had taken the summer before when I realized this was a big problem. This time, with the engine only resting about an hour or two before I drove back, the car had no issues. all seemed well in the world.
THE PROBLEM RETURNS
the other day I wanted to race my friend, and for the first time since I had tested the car on the freeway, I floored it. but this time it bucked again when it was trying to shift into second or third (I can't remember which one) and a few days later the same cat code I had before appeared.
POSSIBLE FACTORS
since I got the car, it has jerked whenever I put it in reverse
I think there are 5 motor mounts in the car, and 3 or 4 of them are bad
the power steering pump was leaking very slowly for a while, which made me burn through belts very fast (fixed now)
I appreciate any tips that you guys have for diagnosing this, I want to get this fixed but i don't want to pay a mechanic an insane amount of money to diagnose it and be wrong. Thank you all for your help.