truck shakes when in OD under 2k

[mdopole]

1994 ford ranger 4.0 auto 4x4. When driving it shifts into OD at around 40-45 mph truck shakes pretty good until rpm's climb up to 2k and above. You can press the accelerator and downshift and the engine smooths out. Runs like a champ in every other gear.

It also rocks back and forth when you first put it into gear and just let the idle move the truck forward or in reverse. When you hit the gas the shake goes away. The truck idles great in park but in gear the truck shakes, but the rpms are still 700-800.

No CEL code thrown. I have owned the truck 2 months now and it has been doing this ever since and has never thrown a cel. I pulled off a connector to see if the cel works and it came on but went back off once i reinstalled the connector.

List of stuff I have replaced to try and cure this problem with no success.

plugs/wires
fuel filter
air filter

tested fuel rail pressure 30psi at idle and reached 39/40 psi while driving
cleaned afm or maf

#5 plug had oil on threads and carbon buildup on plug which i read usually is lower intake gasket leak. I re-torqued lower intake and put in new plug and now looks very clean.

had tranny flushed

new tranny mount

new driveshaft center bearing

dosent smoke or use oil get a gas smell at idle sometimes out of exhaust

This problem is beyond my mechanical abilities. Anyone have any ideas? It not throwing an engine code is what really stumps me.

 

[AllanD]

Doctor! Doctor! My eye hurts whenever I drink Coffee!

Answer: Didja take the spoon out of the cup?

My advice, if the engine shakes at those rpms don't drive there.

The 4.0 isn't the smoothest running engine out there.
And the rather stonk power pulses every 120degrees tends
to make the torsional vibration noticeable so my advice to
you is if you preveive it as a problem "drive around" the problem

Frankly I have also have a 4.0 but with a 5sp manual and 4.10 gears
and relatively small tires and I still consider 5th geat essentially useless
below 55-60mph

My issue with the 4.10's in my truck is I can drive around all day
and NEVER use 1st gear, even way from traffic lights.

AD

 

[Hahnsb2]

Yeah, there's no reason to use OD under 2K RPMs.

 

[WIDTIO]

Im guessing you have the ability to shift between D and OD. For normal everyday driving in town there is no need to use the OD selection. The tranny is always going to work to shift to lower the RPMs, and in your case is causing the shaking. I used to have a 92 explorer and i always just left it in D unless i was freeway speed. At under 2k RPM your engine is 'lugging'

 

[mdopole]

ok thanks guys. Ill just drive in in D and then on the highway manual shift it into OD. I forgot to mention It has 15x8 steels wheels with 235/75 tires on it.

I really like this truck, Its just my first truck. I've always driven old bmw's and hondas the past 15 years and needed a work truck.

Thanks again for the info.

 

[rpkline]

Possible transmission shudder due to torque converter problem?

I don't have much experience with the '94 vintage automatics, but I think that was the last year of the A4LD auto trans in Rangers? I'm not sure how typical it was for them to experience a similar problem to the Ford AOD trans, but I'm having a similar problem in a '90 Ranger with a 302 conversion. The vehicle seems to buck back and forth when it shifts to OD. I drove it home one night and it ran smooth. I went to start it a few days later and it vibrated / bucked / surged mostly when shifting to OD. Based on everything I've changed out and read about AOD's, it seems like it's a torque converter issue on my truck. Maybe the same thing on this 4.0L / A4LD?

I'd think lugging would only be the issue if it was in OD going up a hill? On flat ground, you'd think he'd be able to cruise in OD below 2000 RPM's? Thanks in advance for comments.

 

[mdopole]

Well I think it might be a motor mount that's causing all my problems. The engine rocks back and forth about a 1/2 inch pretty good at idle. I noticed the rubber part of the passenger mount moves with the engine. The drivers side seems to stay solid. So maybe the rubber is torn but not completely busted, just enough to shake around under a good load.

I'll try and get it fixed soon and report back.