Engine has a misfiring after replacing the water pump

SHANNON LEONARD

MEMBER
2002 JEEP LIBERTY
3.7L
6 CYL
4WD
AUTOMATIC
180,000 MILES

I changed the water pump and after putting it back together it starts and runs but it's got a bad miss to it. When I put a code reader on there it said misunderst on cylinder number five, but when I pull that plug out it seems to have nothing wrong with it. So could my vehicle have jump time when I change the water pump and if so how do I put it back in time the easiest?

Saturday, November 28th, 2020 AT 2:12 PM

1 Reply

JACOBANDNICKOLAS

MECHANIC
110,176 POSTS

Hi,

Removal and replacement of the water pump wouldn't have caused the timing to jump, so you are good there.

I'm not sure what you mean by, "I put a code reader on there it said misunderst on cylinder number five." Is there a code you found? As far as cylinder 5, recheck to make sure the connection is tight, clean, and not damaged. Also, make sure the boot that goes over the spark plug is in good condition. Check the rubber boot for gray spots which could indicate the spark is jumping and not making it to the spark plug.

In pic 1, I highlighted where to check the wiring and circled the point to check for evidence of the spark jumping.

Let me know if you did anything other than the pump. Also, make sure the crankshaft position sensor on the right side of the engine block hasn't been damaged. (Pic 2)

Let me know.

Joe

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