02 Mountaineer V8 Problem - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

xanders8 · 02-18-2010, 10:05

Hi all,

Thanks in advance for the help I'm sure I'll get.

I've got a 2002 Mercury Mountaineer AWD V8 with ~98,000 miles. The problem is that I'll be driving (mostly highway) and things will be fine for some time. All of a sudden it will feel as though I took a turn down a dirt road because the engine starts running so roughly that the steering wheel and pedals start vibrating. This can sometimes be cleared up by flooring the accelerator, but not always. Also, at idle, sometimes the problem surfaces and the engine starts running roughly enough that the whole truck shakes. Through this, idle RPM stays at about 800-1000. This happens both when the truck is cold and when it's warm.

The code that's been thrown off by the check engine light says cylinder six is misfiring.

I've had the coil and spark plug on cylinder 6 replaced, as well as on cylinder's 2 and 3 (a few weeks back).

Any ideas? The same engine code has come back (I don't know if the dealer forgot to reset it after replacing the plug yesterday).

Thanks!

**360ci** · 02-18-2010, 17:33

Sounds like a sensor to me. Most sensors are good for a few hours until a long drive. TPS (throttle position sensor), IAC (idle air controller) and even the MAF can affect the vehicle in different ways, such as cutting power, erratic idle even with cruise on going down a flat road, etc. They're all fairly low cost $35-50 each and it's what I would look into first, before buying parts that aren't needed, as these sensors will eventually fail (lifespan of around 70-125K) and replacement will be necessary anyway.

xanders8 · 03-01-2010, 17:46

Turns out I had a bad injector. After trying a few other things the new injector seems to have cleared up the issue.

Thanks for the suggestions!

**Bert** · 03-01-2010, 18:50

Thanks for the update. Always nice to here what fixed it and that you're running good.