Slight miss/knock

19 km/liter = 45 mpg which is quite good.

It wouldn't hurt for you to check the iridium spark plugs and spark igniters, to see if some water has gotten into the spark plug wells.

 

Normally I start driving away and don't notice, but when I stay parked and listen to the engine after startup, it does sound like it misses an ignition every few seconds. It has done this since new, and I have always assumed that it is normal.

The Prius fuel injection system goes almost immediately into closed loop mode on startup. That allows it to run cleaner and leaner, but not quite as stable as with the traditional over rich fuel mixture at startup.

Perhaps you could describe the symptoms a little more precisely, and/or find a nearby dealership or Prius owner and listen to another Prius for comparison.

If I remember correctly, misfires are detected, and recorded in an electronic control unit (ECU). A certain number of misfires is normal. If this number is exceeded, then an error code will be activated which can be read from the on board diagnostic (OBD) system. Someone please correct me if I am mistaken, but I think I read somewhere that, with the proper equipment, the exact number of misfires since the last startup can also be read from the ECU memory.


Patrick Wong has a long record of giving good advice. I agree; it wouldn't hurt to first check the spark plug wells for water.
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Just an fyi kind of thing, but my 2007 Prius almost always idles rough right after a cold start - However, there are no misfire events recorded at all when I look up the history on Techstream or other error codes. Therefore, after reading about it on here often, I feel that its not an actual fault occurring, its just the normal nature of a cold Prius running lean in closed loop (as designed).

 

you show a 2012, what year is the second gen? 35,000 km would be very little use on an 09 or earlier.

 

Please see his previous posts.

 

thanks, not sure what a reconditioned prius is.

 

My guess is salesman's euphemism for "used" or "repaired".

Remember how your engine sounded just after startup?

 

i always attributed the roughness to the valve timing they use. it also shifts rpm's a lot, making it seem even rougher. then again, he might be experiencing the intake manifold problem.