Fella's,
When I fire up the engine, it seems to run on three (out of four ) cylinders. After 5-10 seconds, engines runs fine again.

Any idea what could be the cause? Temp sensor?

THANKS !!

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2011 Prius

With out knowing anything else about the car, my first guess is plugs

John Roncallo

I would guess leakdown on one injector, if the missing is rhythmic and not erratic. Pull plugs before startup and check for one cylinder with a gassy smell.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7

If it's a bad plug(s), shouldn't the engine run bad all the time??

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2011 Prius

The missing is indeed quite rythmic. It happens when the engine is both warm or cold, but always (so far at least ) disappears suddenly and completely after 10-15 seconds, and never returns for as long as the engine runs. Prob seems something electrical to me, and related to the start up procedure. Any more ideas??

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2011 Prius

Nope. Only if they are really bad.

But heres a quick test. You say it runs good after about 10-15 sec. Give it a full throttle acceleration , preferably uphill on a highway, when it's warm and appears to be running good. That will stress the plugs to the max. If it misses under load thats usually plugs.

John Roncallo