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rowekmr's avatar
rowekmr
Explorer
Apr 12, 2018

2007 Ford Explorer 4.6l 3v Missing/Bad Coils

I just got a 07 Explorer Ltd with the 4.6l 3v engine that sounded like a lawn mover when running. The CEL light on with codes P0171 Bank 1 system lean,P0300 random misfire,P0304 Cyl 4 misfire, P0305 Cyl 5 misfire, P0355 Ign coil 5 malfunction.

I have owned a few Fords with mod engines and know the coils go out with time but in the past I had the stealership do them but this time I decided to try to tackle it myself. I got 2 motorcraft DG511 coils and replaced the #4 coil but when I got to #5 it was disconnected from the engine harness and the coil was pulled up out of the hole partially. I replaced that coil also and when I started it the idle was still bad at first but it slowly cleared itself and eventually idled smoothly.

I drove it for 20 miles mainly city driving with no issues but noticed on highway when cruising that the engine missed when I gave it a little gas to accelerate. After that driving it there was no codes so my question is do I need to change another coil? If so how do I now try to find out which coil is bad?

I saw on YouTube that many people put dielectric grease in the end of the coil boot but I couldn't find any at home when I did this. Could that be the problem, should I buy some and use it on the 2 I installed?

Also when I installed the coils they did not sit all the way down on the plug I had to tighten the hold down screw to get them to seat completely, is that normal?