2012 Explorer Heavy Misfires / Highway Speed
 

Good afternoon fellow Explorer owners...

I have a rather weird problem that I'm hoping someone can help me diagnose.

Vehicle info: 2012 Explorer Limited, V6, 98,000 miles.

Already replaced the TPS module ... so this problem is obviously another sensor ... but I don't know which one.

Here are the Symptoms

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Regular Commuting / City Driving: Anything up 40-45 mph
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Vehicle starts perfect, idles smooth and drives great.
Commuting around town ... Perfect.
Tranny shift points are perfect, silky smooth.
No Issues of any kind

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Low to Mid Speed Highway: Anything up 45-65 mph
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Attempting to get out on the highway? Now. We gotz some problems.
Any attempt to accelerate beyond 50 or so will result in severe lurching, feels like severe misfires.
Check Engine light may (or may not) blink for a bit.
You must give it some heavy accelerator pedal to force it to get up and go.

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Highway Cruising: Anything above 70 mph
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Once you get yourself up to highway cruising speed ... Now we're back to smooth sailing. Car will drive perfect...
Unless of course you are forced to drop back down anywhere around 60mph... then you have to give it some juice. (and you'll probably flash the check engine a few more times)

A few things,
There are many things that can cause a misfire. The object is to find out which cyls are affected. Maybe 1 or 2 or maybe all To help get there the vehicle should be checked for codes and which cyls are affected, The flashing C/E light is telling us the misfire is BAD and polluting quite a bit. This leads to another problem that if not corrected promptly can destroy an expensive catalytic converter or two.

Did you just purchase gas and then the problem showed itself. If so, could be some unwanted water in the fuel . Good to have the fuel filter changed before the cold weather hits because if there is water trapped in the filter and the temp goes down that water can freeze in the filter and line and stop the engine completely. When the filter is changed it can be emptied and checked if it contained any water.

Trouble started - out of nowhere - about 2 months ago. We didn't know it was there because 90% of our use of this vehicle is around town / commuting.

It wasn't until I got it out on a trip last month that it made itself known.

ODB2 scan reads a single P0305 code. Cylinder 5 misfire. But the vehicle runs perfectly smooth at all times outside of a specific "load" ... meaning during heavy acceleration. That's what orogonally lead me to believe the Throttle position sensor was bad. But after replacement we still have the issue under heavy load.

You can even "trick" it when you're at highway speed... if you get it up around 70 or so when cruising... then turn off cruise... you just coast for a while. During that time if you manipulate the gas pedal up/down you can recreate the same symptoms of hiccup, cough and sputter. If you ease back off the pedal and bring it up to speed slowly you'd never know anything was wrong.

All signs point me to a SENSOR of some flavor... but it isn't Throttle Position.

Truly stumped.

You are probably on the trail of a problem with a dirty or worn electronic throttle control assy.
Get some "Throttle body cleaner" , a clean rag and have someone hold the throttle pedal to the floor with the key on. Then clean the throttle body inlet. DO NOT USE ANY OTHER KIND OF CLEANER ! See if that gets rid of the problem. If not, replacement of the electronic throttle control motor assy may be the solution..