Rough running Prius

Tiny
SMCGANN92562
  • MEMBER
  • 2002 TOYOTA PRIUS
  • 4 CYL
  • FWD
  • MANUAL
  • 145,000 MILES
My prius runs smoothly when it's cold and most of the time when it's warm. There are times when I pull over and go into a store and it's will run really rough for about 5 minutes of driving. The engine light comes on and gives a random misfire code. I took it into a mechanic and they found fuel in the number 1 and 4 cylinders. I had the injectors cleaned and inspected and the first time that I ran it and then stopped for 10 minutes it started misfiring again. The odd thing is that I can disconnect the spark plug wire on any cylinder and it will run fairly smooth. I'm confused!
Saturday, April 16th, 2011 AT 12:50 AM

4 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
P0300 Random misfires normally caused by vacuum leak and bad fuel fuel-
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Saturday, April 16th, 2011 AT 12:54 AM
Tiny
SMCGANN92562
  • MEMBER
  • 2 POSTS
Would that cause it to misfire when it's warm but not when it's cold?
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Saturday, April 16th, 2011 AT 1:23 AM
Tiny
SPREACKER
  • MEMBER
  • 3 POSTS
I am having the EXACT same issue with my 2002 Prius with 140000 miles. Did you ever find a cause? I had mine in the shop for 3 days and they replaces the o-rings on the fuel injectors because they appeared to be leaking some fuel, but it did not solve the issue. I have cleaned the mass air flow sensor and throdle body. I replaced the plugs last year. The only othe issue with the car is that the A/C only works for a little while and the green light stops flashing and it stops cooling. I assume this is unrelated but thought I would share as much data as possible since this is a tough one to solve.

Thanks
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Saturday, September 3rd, 2011 AT 4:54 PM
Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
As the spark plugs heat up, their resistance increases. That could cause it. It could also be a vacuum leak that doesn't happen until the leaking part heats up and expands. Try running a can of good quality fuel system cleaner through your tank, change the plugs and wires, and check to make sure the coils) is/are functioning properly once heated up.
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Thursday, September 22nd, 2011 AT 6:30 AM

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