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Jittery Driving

I have a 2007 Ford Explorer Eddy B model with 74K miles. When I drive it randomly “Jitters”. The event is difficult to describe. It happens any time; hot or cold, at start-up or after being on the road a while, when I accelerate or am at a constant speed, on cruise control or not. The only time it is not prone to happen is going up a steep incline.

The engine cuts out several times in very quick succession, or once for about 1-2 seconds. It sort of feels like a series of backfires, or that the transmission is trying to find a gear it wants to be in (as I said, this happens even on a level road at a constant speed). When the event takes place, the tach intermittentle and quickly goes from the hormal 1500 rpm (or so) to around 2500 rpm, then returns to normal.

This occurs more often lately.

There is no engine light, so putting it on a test machine is not yet an option. I have changes all the filters and uses the gas stuff to eliminate water. I let the tank get down to 50 miles of driving time and then always fill the tank.

What might be the problem?

Thanks,

Fat Old Fart

Putting it on a test machine IS an option.

First of all, ECUs can store codes without lighting the CEL.
Secondly, “test machines” can detect erratic spark pulses, erratic sensor signals, and other things that can point directly to the problem but can be felt only occasionally in routine driving. And then there are things like the fuel pressure regulator that can be tested but don’t cause a CEL light.

Don’t underestimate test equipment. In the right hands it can di far, far more than just read codes. And in this case it might even read a stored code.

Here, perhaps the attached link will be a revelation.
http://sunequipco.com/electronic%20test%20and%20measuring%20equipment/automotive/automotive%20index.htm

I’m thinking that the transmission is hunting between 2 gears. Why else would the tach show revs going up? If it was an electrical failure and the engine was stalling, the revs would go down. The fixes you tried are all engine related, but the problem sounds like a controller in the transmission.

Wentwest, I’m inclined to agree.

I also tend to agree. If this transmission has a lock-up torque converter it may be failing which would cause a shudder/jittering feeling in the driveline.

Torque converter lock-up dropping out was my first thought, though 1,000 rpm change is too much. So that suggests hunting between 3rd/4th.

It doesn’t really change what mountainbike said though. The first thing I’d do (ok - after checking the transmission fluid) is put it on a scanner and check out the throttle position and mass airflow sensor signals. Whatever speed sensors are around also need a look.

There’s also well over 100 (1700-series+) fault codes that a tranny can throw that a “test machine” can read.