rob_engineer

My 2012 jku is approaching 85,000 miles. Question is whether anyone replaces the spark plug coils as preventative maintenance. I ask because I've had two events within the past year on other vehicles when a coil went bad. The price for a a coil at the local auto parts store was more than double what the same part sells for on the internet. But, when those failures occurred, I did not have the luxury of waiting two days for the part. So, I'm thinking when the time comes to change my spark plugs, it may make sense to do the coils also. Your thoughts?

ronjenx

Might as well replace the PCM and TIPM, too. People have had problems with those.

Just kidding, of course. Where do you stop, though?
If I were worried about coil failure, the most I would do is have a spare one on hand.

rob_engineer

yeah, having one in hand is probably a good compromise. My recent experience was on a friends old Hyundai car that developed a sudden problem. Troubleshooting led to the conclusion of a bad coil. Auto Zone had one for about $80. On Amazon, I could get a whole set of 4 for about $50. It was frustrating to spend the $80, but the car had to be fixed that day. I haven't done plugs in my JKU yet, but I understand you have to remove the intake plenum. I'm not sure how easy or difficult that is, but that will factor into my decision of whether to replace those coils.

Four Low

Remove Intake Plenum to change SPARK PLUGS ? Say it ain't so ?
I think you have to remove the cab on Ford Trucks to replace rear plugs, so maybe not so bad

rob_engineer

the few "how to's" I've read about the 3.6 say you have to remove the intake plenum for one of the sides. I once had a 91 olds cutlass. For that car I had to remove the alternator which created just enough space to cram my arm between the block and fire wall to get the plugs. My arm was bruised and bleeding by the time I got the plugs replaced.

ronjenx

That was just from being pissed off the whole time, right?

According to the instructions I have seen, the upper intake manifold has to come off to remove the left bank plugs, (2, 4, 6), which requires a lot of peripheral disassembly.

rob_engineer

yes. And to make matters worse, on that Cutlass, the act of removing and reinstalling the alternator made the alternator fail a couple days after the spark plug job! The car had 140,000 miles at the time. Another thing that pissed me off was that at 43,000 miles I paid a mechanic to change the plugs. Years later and at 140,000 miles I discovered that mechanic never did change those rear plugs. They were still trying originals! He did change the easy ones though.