150000 miles Yaris 2011 poor acceleration and power fluctuations.

[Charlieclangers]

Originally Posted by mirageman

If you are driving along in the same gear and same pedal position and you feel power fluctuations, that tells me you potentially have enough power, as opposed to an engine that needs replacing which would run with low power all the time. Are there times when it feels like you have adequate power? That p420 is a concern. Perhaps your catalytic converter is clogging up? First things first, spark plugs and BG44K fuel injector cleaner. Clean your throttle body too. EGR could do that power fluctuation too, but not sure if you even have one. Variable valve solenoid problems can be a pain when they are sporadic, and you should get a code if it were the solenoid. No code other than the 420 looks like it may just be the second oxygen sensor, but I am still a bit suspicious of the catalytic converter despite the pressure check you mentioned. That could be a big job. There are many things to check before getting an engine. Compression testing is also an easy check for each cylinder, and you'll get to see and/or change the spark plugs while you're at it. A code reader could also tell you if there are any PENDING codes, codes that haven't tripped the computer enough times to make a light on the dash. Could also be a fuel delivery problem, meaning pump and/or filter. Tough to test that on your own too, so I would go the easy route and go with a fuel injector cleaner, my favorite being BG44K, and checking compression and spark plugs. Good luck if you're still dealing with this.

I have to say well done - You outdid a Toyota main dealer without even seeing the car. When i took the car back to the trade seller i brought it from for them to replace the engine they said they wanted to double-check somethings before removing the engine and they discovered a clogged first stage Cat. So rather than a £600 job it was a £250 job.


Thanks for all the suggestions everyone



MYSTERY SOLVED