Stuttering drive train

[corey@lfgpottery]

Given the amount of information presented in this forum I have no choice but to assume this very issue has an entire thread devoted to it. But given the size of this forum and my inability to determine the actual problem, I think I’d be an old man before finding the thread.

At present my 2005 XLT 4.6 has a stuttering/chugging/slipping/slamming issue in the drive train.

Initially I assumed it was a tranny issue and proceeded to buy a rebuilt unit and have it installed. The tranny guy I took it too disagreed and though it was instead a result of chain slippage in the transfer case (TC). After draining the TC he noted no metal in the fluid or any damage visible though the TC plug so we moved on to the tranny.

When the tranny was drained it became obvious that the tranny had issues. The magnet was “fuzzy” and the fluid was almost completely black with metal. Based on this we swapped the 5R55S tranny with the like rebuild and took her for a test drive. And yes my Explorer is a “her”. She’s a pretty red lady.

During the test drive the stuttering was experienced again. As a result I purchased a used TC and had that swapped out. Tested it again. And alas, still stuttering. My tranny guy was confounded as he was sure the stutter was coming from the TC so he unplugged the TC electronics and drove it again. Smooth as butter. Well in an explorer it’s more like smooth as marmalade but you get the picture.

Based on that, we assumed that the recent removal and subsequent replacement of one of the pressure sensing valve stems with a standard non-sensing valve stem was causing the CPU to repeatedly engage the front drive shaft and then immediately disengage it.

The engaging and disengaging does seem to be the issue, however replacing the valve stem didn’t resolve it. I am now mostly at a loss as to what is causing the shuddering in the drive train.

Is there a controller unit or some other electronic component out there that could cause this?
Has anyone seen this shuddering problem before?

At present I really can’t drive the vehicle as the shudder will cause other issues if driven like this for long. As a result I have been out of a vehicle now for 40-weeks. I am getting so confounded and frustrated that I have even daydreamed of sending the vehicle back to Ford through the dealerships from window.

If any of you know what this issue is please help me to love my lady again and prevent me from further dreams of a high speed introduction between my lady and the Stealership window.

 

[fusseli]

Sounds like the usual unintended engagement of the transfer case. How unevenly worn are your tires, and are they the same size?

 

[Exproblems]

My tranny guy was confounded as he was sure the stutter was coming from the TC so he unplugged the TC electronics and drove it again. Smooth as butter. Well in an explorer it’s more like smooth as marmalade but you get the picture.

Based on that, we assumed that the recent removal and subsequent replacement of one of the pressure sensing valve stems with a standard non-sensing valve stem was causing the CPU to repeatedly engage the front drive shaft and then immediately disengage it.

The engaging and disengaging does seem to be the issue, however replacing the valve stem didn’t resolve it. I am now mostly at a loss as to what is causing the shuddering in the drive train.

.

If your tires are unevenly worn, different sizes or you have a miss-matched set of tires on the vehicle, the auto 4x4 system(going into to 4 wheel drive) maybe kicking in and out causing the front end noises you hear. When I test drove my EX at the dealership, the rear tires were worn down badly and unevenly(fronts appeared okay) and while I drove down the road(snowing at the time), I kept hearing a clunking sound in the front drive train/wheels area, especially when I took off from a stop. I didn't know anything about auto 4x4 at the time, but I told the dealership about the clunking front end noise and told them I wanted new tires put on it which they took care of. They told me they put a new chain in the transfer case, but I think that was BS just to make me happy. It was the new tires that took care of the auto 4x4 kicking in problem because the tires that were on the vehicle, were badly uneven in wear. So check your tires for uneven wear, sizes or tread patterns.
On the Tire Pressure Monitoring System valve stem change, don't know if changing one valve stem with a non sensing stem will cause the auto 4x4 to kick in, but my EX came with all 4 TPMS valve stems removed from the rims and all it causes is for me to see a TPMS warning message fault on my message screen when I start up the vehicle. I just clear the message by hitting the "reset" button, but it does not cause auto 4x4 to kick in not having the 4 TPMS valve stems in place in the rims.

 

[n2epv]

I have a 2004 4.6 explorer and wanted to add my experiences after 85,000 miles. My 'ex developed a problem a few years ago with the transfer case clutch engaging when it should not. It was doing it on dry smooth pavement at speeds probably between 40 and 60 mph, and was a rythmic on/off about once every 5 seconds. Others in the forum have posted about this and the feel and sound it makes is similar to running over a garden hose (or those traffic counter rubber hoses). In other words, not very loud or harsh.

There are a number of threads for dealing with this - look for 'brown wire mod'. One common observation seems to be that the transfer case clutch problem never very harsh when it happens. In fact, I had it for 6 months or more before I realized it was the truck and not road surfaces.

On a related note, my '97 mounty 5.0 has a problem where the torque converter clutch slips under acceleration at certain conditions. This seems to be a common problem with that model transmission (plus at 210,000 miles, things are bound to act up). This slippage problem is loud and harsh enough to be very obvious (unlike the third-gen 4X4 clutch slippage). I added a switch similar to the 'brown wire mod' to disable it.

 

[n2epv]

I read through the posts again for this thread and another thing occurred to me - unlike a 5-speed automatic transmission, a transfer case is stupid-simple. If the chain is indeed slipping (I'm not a mechanic, but would think this is a really serious issue and you should not drive the truck) - anyway - pulling the case apart on the original unit should make it quickly obvious if this was the problem.

Again, I am not a mechanic, but I've been driving, abusing and breaking 4X4's for years... other ideas:

- the valve stem TPMS's only control the light on the dash. The 4X4 system is controlled by the wheel speed/ABS sensors. By the way, if you live in an area where your vehicle encounters road salt, expect these sensors to give you trouble sooner or later!

- a broken gear tooth in a differential will cause some really loud and nasty things to start happening. The truck will still drive, but you want to get this fixed promptly!

- the 3rd gen 4X4 system is not the best. But, if you can get around without 4X4, leave the fuse out (or the connector on the TC off) and see if the problem stays gone. This won't hurt anything - just avoid spinning the rear wheels. If this eliminates your shuddering, then the problem is probably in the front diff or transfer case.

- find an honest mechanic that does trucks/4X4 drivetrains and have them diagnose it. Shop rates being what they are, this may be several hundred $$$, but will be money well spent.

- my '04 V8 explorer has been well worth what I paid for it, but not exactly trouble-free. It's always fun to drive and with the safety factor, I would have trouble going back to a car that weighed 1000's of pounds less but got twice the MPG.

 

[n2epv]

One more thing - I used to be a civilian contractor for the Navy and worked in Bremerton/Silverdale for a while. I really miss the summer weather there!

 

[corey@lfgpottery]

I had a bad set of tires on the vehicle. I realized this when doing the brakes, before I noticed the stutter. I then replaced the set with a used set which exhibited similar wear, that wear being such that the back tires have about 1/8 more wear than the front. The set I put on as used is in good condition.

It sound like this is the issue and I will be looking at doing a 4 tire replacement to confirm. Now what I want to know is what damned engineer designed this system to react after only a difference of about –inches circumferentially. As an engineer I find this to be a serious design flaw intended to line the pockets of tire manufactures.

Is or was there a class action related to this issue? If I designed a building to be rendered useless after only –inch of deflection I would be sued, repeatedly.

 

[corey@lfgpottery]

I had a bad set of tires on the vehicle. I realized this when doing the brakes, before I noticed the stutter. I then replaced the set with a used set which exhibited similar wear, the back tires have about 1/8 more wear than the front. The set I put on “as used” is in good condition.

It sounds like this is the issue and I will be looking at doing a 4 tire replacement to confirm. Now what I want to know is what damned engineer designed this system to react after only a difference of about 0.125-inches circumferentially. As an engineer I find this to be a serious design flaw intended to line the pockets of tire manufactures.

Is or was there a class action related to this issue? If I designed a building to be rendered useless after only –inch of deflection I would be sued, repeatedly.

 

[fusseli]

It's not a design flaw, it's how the A4WD system is intended to work. Allowable uneven tire wear (if you actually read your owners manual) is 2/32" for all 3rd gens.

 

[oshp367]

Stuttering

I too am having the same problem in my 2003 Explorer. I have replaced the 4x4 module, throttle control sensor, and so far it still does the same thing. Put it into 4wd high and no problem. Back to Automatic 4wd and the stuttering come back. This has been going on for 2 years on and off. I do have one worn tire on the rear but really dont want to buy news tires just to test the theory that a worn tire causes this problem...

 

[Exproblems]

I do have one worn tire on the rear but really dont want to buy news tires just to test the theory that a worn tire causes this problem...

One overly worn tire will cause the problem you are having. When I bought my Ex, 2 of the tires were badly worn down due to out of alignment, 2 tires looked good, even tread, and the auto 4x4 kept kicking in and out as I test drove it down the road. I knew nothing about auto 4x4 till I found this forum. Once the dealership installed 4 new tires, along with a new wheel alignment I requested as part of the purchase agreement, the problem with auto 4x4 kicking in and out stopped and hasn't done it since in 2 1/2 years.
Since you don't want to spend money on a new set of tires, you can always pull fuses #17 & #18 to disable the auto 4x4 system and this will stop the problem you now experience unless you have some other type of problem going on.