56mph to 64 mph miss/skip/studder?

[my87bomb]

I have searched however, while driving(outside temp doesn't matter engine temp doesn't matter) between the speeds of 56 to 64mph my ranger will start to skip/miss when I try to accelerate the skipping gets worse and turns into a bucking feeling almost as if it is loosing fuel. Driving at 54mph and below and 66mph and above I do not have this problem. I am thinking MAF or TPS? BTW this is on my 99 3.0 flexfuel ext cab auto. 2wd ranger130,000 miles...I recently replaced the plugs and wires(motorcraft) and coil pack(autozone). It was running like dirt when cold prior to this and I searched and found a hose missing from egr area to the pulse sensor. now it runs like a champ except between the speeds as stated above...I have not replaced the fuel filter yet...but...something like that should be constant this is at any rpm just between those certain speeds. only codes (DTC) are lean banks 1 and 2.
Thanks in advance for any and all help.

[kodex]

Could be your EGR system causing your computer to do screwy things with the fuel/air ratio. Try popping it off the throttle body and soaking it in some carb cleaner, but don't you dare get it on the electronic part! Another option would be using MAF sensor cleaner, which is safe on electronics (just gotta make sure it's dry before putting the valve back on.)

-Steve

[Rearanger]

Originally Posted by my87bomb

I am thinking MAF or TPS?

No guarantee that TPS position is always the same at any speed. Throttle opening depends on engine load. MAF measures air flow/density/temperature so speed I'm thinking is not going to be that defined there as well. I agree that fuel filter does not fit the symptom, although it would be a cheap test. Bucking could be electrical or fuel starvation.

A quick OHM test might see if you have a flat spot in the TPS windings but Ford calls for volt testing the TPS.

How does it behave in all gears independent of speed?

[my87bomb]

Steve - I will have to try that, worst case I need to get an egr valve gasket....

Rear - I did replace the fuel filter, to no avail symptom is still there.
I however, have noticed under very hard acceleration(flooring it) it will produce the same symptoms, i very quickly let off though because of how violent the truck bucks jerks and shakes. When i get back on the throttle...no more than about 30% it accellerates smoothly...untill i hit about 58 or so...

[Rearanger]

Can you check fuel pressure?

[my87bomb]

Rear
Not without taking to a garage somewhere...which I think I am about to do! The speed range is getting bigger. It does it now from 54 to about 66.

I took the egr off it looked fine to me, no exsessive build up of carbon or anything. I am about to try the two different sensors by the throttle body.

[my87bomb]

UPDATE
I swapped the TPS and MAP sensor one at a time with used ones, no change in symptoms... I know...how do I know the used ones were good(i dont)
I cleaned the MAF w/ Electronics Cleaner(brake cleaner)
and today I performed a compression test...
when looking from the front
3-6
2-5
1-4
starting with #1 122, #2 128, #3 135, #4 137, #5 110, and #6 145...
yes I am concerned about a 35 psi difference between cyl # 5 and 6 but the engine does have around 130,000 miles
Refresh---its a 99 3.0ffv A/T

[Rearanger]

I thought the FFV had higher compression to compensate for less energy in alcohol. Those compression #'s look really bad (if gauge is accurate) but I can't see how compression is related to missing at certain RPM range. Was the engine hot when you did the test?

At about 11K miles my compression was between 192 and 185 (I can't find compression spec in my FSM). I don't consider your 130K a lot of miles. My 95 Camry has 185K and 170psi compression, just 8 PSI off new factory spec.

Have you tried getting to the RPM range in all gears and seeing if the problem is the same in all gears at same RPM range or just in top gear at those RPMs?

[my87bomb]

Rear
I've read where the valves are different in order to handle the ethanol but haven't heard wether or not the compression went up. As for trying it in different gears, thats the weird part. It has the same skip/buck but at higher rpms in lower gears. I thought it was slaming in and out of O/D. A friend of mind said it may be lock up acting up. So i ut it in low 1 to see if I could get the jerk/miss. It wasn't as violent but it was at higher rpm's
I am thinking of either installing a tach to verify the rpms or just send it to a garage. I personally think it's in my injectors. But I am at a loss when it comes to checking that. because the symptoms only appear while driving. I tried to power brake it with no signs of the skipping/bucking. ?????

[masterbrenden]

check the comprestion to what it should be. the flex fuel's do have valve problems and will suck the valve into the head over time and cause a miss at high speed or high load

[Earl43P]

Disconnect the vacuum line to the EGR valve and drive it.

If it quits bucking, replace the DPFE.


Lean in Banks 1&2 is very likely to be the infamous PCV 90 degree elbow leaking, which is very common.

[my87bomb]

Earl, tried it, and it made no difference...