Engine Troubles

[Sabin]

So my 2006 Explorer stared running very rough recently. After looking into the codes I made some repairs which included replacing the plugs and coilpacks as well as some wiring. This fixed some of the issues and most of the codes, however, I how have P0171 (too lean) and a misfire on cylinder 7. The issues include major engine/body shaking in all gears (P/R/N/D) and really poor gas milage (around 5 mpg).

Any recommendations on what I should look into next?

 

[Bazz270]

What brand of spark plugs and coils used?

 

[Sabin]

What brand of spark plugs and coils used?

I don't remember off the top of my head but I know they are not the issue. The ones I replaced were Motorcraft and I tested each new one by swaping them out with a working old one and there was no change, I only replaced them because I needed to to remove a U0101 code.

 

[94Eddie]

History here has shown that using non OEM plugs and coils have caused many issues. Even brands like MSD can cause issues. Below are a couple of good videos about trouble shooting lean conditions but you'll need to have access to live data to see what long and short term fuel trims are doing. Miss fires for a single cylinder is most always a coil, spark plug or fuel injector issue. Since you have a 2006 model it could also be degradation of the insulation on wiring cause shorts or impedance changes from specs which is a known issue with the 2006-2008 model years. Look at the insulation for the wires running to the coil and fuel injector connection for cylinder #7.

 

[Bazz270]

I don't remember off the top of my head but I know they are not the issue. The ones I replaced were Motorcraft and I tested each new one by swaping them out with a working old one and there was no change, I only replaced them because I needed to to remove a U0101 code.

ok.

what is the 7th cylinder spark plug brand? How old the spark plugs are? why do you thing the spark plugs aren't an issue?

misfire simply means bad coil/moisture on the spark plug /high mileage large gap whatever carbon built spark plug/deteriorated insulation/clogged catalyst ..there is no magic

if you are in case of high mileage or non OEM spark plugs, replace the whole set and comeback for a feedback. spark plugs a with 50+ k miles are potentially suspected for a misfires and other ignition troubles, especially the aftermarket ones.

 

[Sabin]

ok.

what is the 7th cylinder spark plug brand? How old the spark plugs are? why do you thing the spark plugs aren't an issue?

misfire simply means bad coil/moisture on the spark plug /high mileage large gap whatever carbon built spark plug/deteriorated insulation/clogged catalyst ..there is no magic

if you are in case of high mileage or non OEM spark plugs, replace the whole set and comeback for a feedback. spark plugs a with 50+ k miles are potentially suspected for a misfires and other ignition troubles, especially the aftermarket ones.

I just replaced the spark plugs (I don't remember the brand but they were some iridium ones from rockauto) and coilpacks which is why I believe they are not an issue. I also moved the set from #7 around and the issue stayed at #7 which is why I'm leaning towards them not being the issue. I'll try and check the fuel injectors next as well as the wiring. I already had to rewire two coilpacks but I was getting codes for the ones that weren't working so I don't think the wiring is the issue.

 

[Bazz270]

Camshaft rocker mechanism issues?
Check compression on #7 cylinder