I own a 2001 Prius (196k miles) which runs rough whenever the gas engine is off for more than 3 minutes, cold or warmed up. It runs rough for about 1 minutte than runs smooth.
My Toyota dealer has changes spark plugs and is now doing all sorts of diagnostics. They want me to okay a compression test (aprox $100) and replace the PCV valve (aprox another $100). They supposedly did a tune-up 2 weeks ago and did not find any issues except for the plugs. Check engine light is on, codes say multpile misfires.
Most of the problems started after Toyota did their 30,000 mile service a couple months ago.
Any guesses on what making it run rough?
Clean out the idle air control valve and see what happens
September, 3, 2011 AT 5:09 PM
My Prius is having the same issue. Did you ever get yours fixed?
September, 6, 2011 AT 3:53 PM
I have not been able to find a solution yet. My local Toyota dealer cleaned the throttle body and says this cleaned the Idle Air Control Valve(IACV). I then decided to replace the IACV so the next nearst dealer told me $1200 to replace it. This sounds like replacing the whole throttle body. The 3rd nearest dealer to me said there is no IACV, but a wire controlled by the computer.
I'm still getting 46+mpg suburban driving so overall so the rough running is not affecting my milage, and the Check Eng light went off for 1 day last week so I took it in and passed the "smog" test. Maybe a small piece of electrician's tape will fix the light, but I still do not know what to do about the rough running.
Let me know if you find a fix, I seem to have hit a wall that I can't get over without a lot of cash.
September, 6, 2011 AT 6:07 PM
Just to help narrow it down, which of these things listed above can make it run rough only after the gas engine was off 3 minutes(hot or cold) or more, but still runs great after less than a minute and still gives me fantastic gas mileage?
I'm not a mechanic, but it seems to me that all these listed possibilities would hurt the gas mileage or would result in a constantly rough running engine, not temporarily and only after 3 minutes of down time. If off for anything less the gas engine runs fine.
It almost sounds like a programmimg issue to me. I really appreciate your time on this.