Cylinder 2 misfire, cylinder 3 down on compression

[Gareth Randall]

I’ve been getting misfire issues for a couple of years now on my 2005 Jeep Liberty 3.7L. It’s always a P0300 random misfire at first, which after a while gets pinned down to a P0301 or 0302. Recently, it’s only ever been 0302.

I’ve changed plugs and coils twice, and now I’ve finally got around to doing a compression check. All the cylinders are fine except #3, which is down, but still within the 25% variance allowed by Chrysler.

Could reduced compression in #3 trigger a misfire code for #2? The firing order is 1-6-5-4-3-2, if that has significance.

Topic

[college man]

Usually with a specific cylinder it would equate to spark,fuel or compression.
see if this helps.

http://www.justanswer.com/jeep/6o41i-jeep-liberty-2010-3-7-p0300-p0302-replaced-plugs.html

[Bluesnut]

What kind of compression numbers are you talking about? I’ve seen a lot of erroneous information on compression numbers and allowable cylinder variation even in factory service manuals.

[Travis]

Just wondering. Was compression check done with all plugs out and throttle plate open? Not doing so can skew the results. Especially if you have compression going between two cylinders. Eric has a great video on dry and wet testing.

[Author]

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