Consistent cylinder misfire

Toyota's greatest minds have been on the case for years and yet the problem remains for some. I doubt our speculation is going to improve on what the makers have already discovered.

 

yes, that's exactly how everyone describes it. grumpy is right, no home grown solutions other than avoiding the cause.

 

I do not know if this might help but here it goes. Back in September of this year I took a 15 day staycation. I own a Prius PHV and I did a lot of short trips on a daily basis during my vacation. If you know the PHV Prius, you know that you can trigger the engine if you go into the PWR zone. During those 15 days I had the engine engage a lot of times for just a couple of minutes due to my lead foot. This resulted in the engine operating while cold and never reaching full operating temperature. Once my vacation was over, I began to notice a rough start of the engine in the morning when I was going to leave for work. It began as a bit of a shaking and started to get progressively worse. It got so bad, that by the 28th of September the engine would misfire for several seconds. You could hear the engine trying to start, puff, puff, puff with the starter motor keeping it going. The problem started to occur more frequently, every time the engine got to ambient temperature. This was in September and I live in Texas, I can assure you the temperature was nowhere near cold. I recalled reading about water in the intake manifold causing the misfires and it sort off made sense to me. I had driven the car short distances without allowing the engine to warm up every time it started. We also had a humid climate this year in September. During the summer I had noticed from time to time a bit of a rough start but it was not anything major. Since I figured I had moisture problems within the intake manifold, there was only one solution. To get the manifold hot enough to evaporate the moisture and drive it out during the normal combustion process. Luckily I had a conference in Galveston that I needed to attend. Instead of driving or taking one of the company cars, I decided to take the Prius (It didn't hurt that the IRS has wonderful guidelines for mileage reimbursement!!!). So off we went, two co-worker and myself on a 5 hour drive from Fort Worth to Galveston, TX. We average 75mph all the way down and all the way back. In all, we put about 700 miles on the car when it was all set and done. I can tell you that the day after we returned from Galveston the car started right up with no problems at all. A few weeks ago we got hit with the polar vortex and we had temperatures hit 34 degrees for the high and 23 for the overnight low. The car started like a champ. I truly believe that in my case, I had a moisture problem within the intake manifold. While a road trip might not be feasible for everyone, it is worth a try. At the very least just drive the car on the highway for an hour or two. Hopefully this helps someone.

 

when you say 'the engine never reached full operating temp', did you shut it down before the warm up cycle completed?

 

I strongly suspect that he is wrong with that statement as I do not believe that the engine will automatically shut off, certainly not repeatedly, without coming fully up to temperature.

That does not, however, in any way invalidate his overall experience.
He obviously "burned off" something; maybe water in the manifold or maybe something else.

 

agreed, it does not turn off by itself until it has completed the warm up cycle for emissions reasons. i was thinking he either arrived at his destination, and the engine was still running when he shut it down, or, as some pippers do, pull over and shut the car down and start it back up, the ice will not come back on.

 

If that's the case, he's the problem.

 

yes, it has happened to others.

 

I'm getting the feeling there is a head gasket leak issue with GEN III Prius's - I went through all the symptoms you describe and all the typical Toyota fixes (ingition coil, fuel injectors, intake manifold gasket, EGR, etc.) - finally took the head off and found the engine cylinder block was warped due to prolonged head gasket leak/misfire causing excessive head in block (the explanation I was given). Car was impeccably maintained by dealership - end result - junking car, buying new. Made to 300K - early for a Prius.