4.6L stumbling/bucking

[galbre]

Hey guys,

My 2002 4.6L has 168k miles. Over the winter (about a month and a half ago) it has at times bucked or stumbled. It feels like it is coming from underneath the center console. It doesn't do it all the time, maybe once a day. At first I thought it might be a coil pack but this doesn't feel like its coming from the engine nor is it throwing any codes. Lately, the weather has warmed up and it doesn't seem to be doing it.

Does anyone have any ideas what the cause is?

Thanks,
Gregg

 

[Number4]

Mine does this at times during down shift. The transmissions from what I've read are problem prone.

 

[Limited02]

Can you explain more about when it happens? Is it when you first start it up? When you are driving? Accelerating?

 

[galbre]

It happens when I'm driving (not idling at a stoplight) and when I'm either at steady speed or accelerating. The tricky part is that it doesn't happen all the time. We've warmed up recently into the 20s and 30s and it hasn't been doing it lately as much. Thanks.

 

[galbre]

It happened a lot tonight while snowing out. Could it be related to the auto 4x4?

 

[pet575]

Another possibility is the MAF sensor. Mine went completely bad when some snow got into my air intake.

 

[Limited02]

It happened a lot tonight while snowing out. Could it be related to the auto 4x4?

Doubtful on the 4x4 auto since I was playing around the last few days with mine on snow/ice. Then again, it's always something you'd never expect.

I had an issue each winter when my Explorer would stumble on startup when below freezing and would not idle. After several minutes of driving, it would all the sudden come to life and run great. Turned out to be the IAC was very dirty and after cleaning it, all was well.

I'd clean the IAC and the MAF sensor just to be sure since that would be the easiest/cheapest route. It's possible one of your COP's (Coil On Plug) would be going bad or spark plugs need to be changed. I had a bad hesitation at part throttle and it turned out to be the COP's.

When was the last time you did a full tune-up?