Tiny win - figured out why my 3.6L kept misfiring on cylinder 5

After swapping plugs and coils twice on this Pentastar I still had a misfire. Finally grabbed my multimeter and found the ground strap on the harness connector was actually broken under the insulation. 20 minutes and a new pigtail later it ran perfect. Anyone else ran into hidden wire damage that throws off diag for like hours?

3 comments

3 Comments

sethfoster1mo ago

Had the same damn thing on a 2013 Wrangler. Wasted a whole Saturday chasing a misfire on cylinder 4. Pulled the harness apart and found a wire that looked fine but snapped clean when I wiggled it. Crimped in a new pin and it fired right up. Now I always check the harness with a meter before throwing parts at it. Saves a ton of headache.

jamie_webb671mo ago

Funny enough I found a cracked ground wire on a lawnmower once doing the same thing.

claire8721mo ago

Yeah I read a thread on this a while back on some jeep forum where a guy was chasing a misfire for like 2 weeks. Turned out the wire was pinched under the engine cover where nobody would ever think to look. I've started doing the wiggle test on every suspect wire now, even if it looks perfect. Saves so much time compared to throwing parts at it.