I have a '97 4X4 4.6L with both the off road, and towing packages. While I'm driving on smooth flat roads about 50 MPH (1K-1.5K RPM) , after the Torque Convertor locks up in OD, I get a stutter for a fraction of a second. It almost feels like a miss-fire in the engine, but it doesn't do it in any other gear, or during idle. I originally thought that it was my A/C compressor engaging, but it does it even with the A/C off. I've asked Ford to check into it, but suprisingly , they cant find anything. ARGH!

I'm not sure which tranny I've got, but I just had a full service a couple thousand miles ago, didn't seem to do anything.

If anybody else has this problem, or has any insight directing me to a solution, I'd greatly appreciate it!
Thanks!

 

First, you have the 4R70W transmission. That's the only automatic available with the 4.6L.

You have the classic symptoms of torque converter shudder. Changing ALL the fluid in the transmission almost always cures this.

When you say you had a full service, what does that mean? The best way to change all the fluid is to use one of the machines that taps into the cooler lines. This will flush out the old fluid and replace it with new fluid. You need to use MERCON V fluid, too.

Mark

 

The service I had done was the pan drop and filter change. I've had the tranny flush done several times before at the local oil swap place, and I'm sure that they've never put mercon V in it but rather what they consider to be a comprable fluid. I'll have to go ahead and try the flush to see if it takes care of the problem.

Thanks for your input Mark!

~Julien

 

Dropping the pan changes less than half of the total fluid. I think a flush may produce a big change in your transmission.

Mark

 

I know exactly what your talking about because my 97 4.6 with 4R70W, and tow package does the smae thing too. I usually feel mine on very light acceleration or slight incline while traveling 40-50mph and 1-1.5K RPM. It will sometimes just shudder once sometimes it will do it 3 or 4 times. I have noticed it does it right before a downshift point, almost like the TC is stuck or the PCM can't make it's mind up to shift or not. It will also do this on the interstate at right around 70 mph and 1900-2200 RPM, again it feels like it's right before a shift point. If you go ahead and accelerate a little more it will stop or go ahead and change. I have bigger tires but have changed speedo gears and speedo is accurate withinn 1-2 MPH. It was off up to 3 mph with stock tires and gear.
I had a complete flush done by a Ford dealer with a BG flush machine. They used regular Mercon but added Lubeguard's Instant Shudder fix. After 1000 miles the problem is still there. The tech took the truck for a drive and did feel the problem but said it felt like a dead spot in the engine. He had no further clues on what it is without it a code flashing or spending major $ to throw parts at it. He siad it could be engine or trans.
If nothing worse happens between now and 5000 miles from now. I plan to drop the pan, change filter, refill with quality Mercon V, and possibly add a shift kit with the two Sonnex valves, especailly the bypass clutch control valve. Which helps to prevent and eliminate torque converter clutch slip and shudder concerns in 4R70W transmissions. I have also thought about a recalibration of the PCM or total replacement of the TC. A stock TC is under 200 I think and performance units go for as much as 1000. I plan to have AAMCO perform a free diagnostic on the tranny whenever I can. I have also thought about and had suggested such things as the transmission range sensor and the TPS too. If one of these was it I would think it would thorw a code or do it more often. It must be a mechaical problem somewhere.
Let me know, if you find anything out. This little quirk is bugging the hell out of me. I know none of this really solves your problem but things I have thought about.

 

If you decide to change the fluid again, use MERCON V. It was developed to eliminate shudder. Also be sure to drain the torque converter, too. If you only drop the pan you will change less than half of the fluid.

Even better would be to use a flush machine. This will change about 95% of the fluid.

Mark

 

psyberjules,
I am having nearly the same problem as you. I have 2000 F-150 w/ ORP and tow package, and I'm having this 'vibration' between 40 and 45 MPH. I've changed the tranny fluid to no avail. Had new tires put on, didn't help. Rotors were turned, still shook. I had the wheels and new tires balanced again Friday, and it seems to nearly have gone away for now. I now only feel a very small vibration around the shift into OD. I've had the truck to Ford probaly 5 times over the last 1.5 years and 20 k miles.

The Ford techs really don't feel it, but they aren't used to how the truck drives. They told me it is NOT in the tranny because it shakes when accellerating or decelerating, and even when coasting in nuetral.

We (me and the techs) are beginning to believe it is a harmonic oscillation based on the geometry and mass of some part on the truck. They are supposed to be checking for similiar complaints and getting back w/ me. I personnal believe the problem is originating from one or more of the wheels. I'm supposed to be hearing from the Ford rep on this issue soon also.

Have your wheels/tires road force balanced and make sure they puts weights on both sides of the wheel. When they put the new tires on my truck, for some reason they only put weights on the inside of 3 of the tires, and on both sides of 1.

 

Ask your dealer to use an NVH(noise vibration harshness analyzer) if they have one in their shop. If they dont, you might want to consider another ford dealer that does for this problem. Using the NVH will almost always find the source of a vibration concern. It's a great tool, but a lot of dealers do not have it.