Do I have a transmission problem?

[benenglish]

I think the answer is "I'm about to" but I know better than to trust my instincts.

2002 Mercury Gran Marquis, 121k miles, last routine trans service @ 50k or 60k. No history of trans problems.

Trans fluid smells fine; I know what burnt fluid smells like. Level is fine.

Potential problem - Over the last week, the upshifts have changed. Upshifts with this car have always been a tad firmer than you would expect. Now, they're suddenly butter-smooth. Shift points remain the same. Under gentle acceleration , the 1-2 is at ~25 mph, the 2-3 at just under 40. Revs don't go past 2000. Under moderately spirited acceleration, the speeds remain the same but the revs go up to ~2500. I have to concentrate to feel them, they're so smooth.

Under full throttle from a standing start, the upshifts don't happen. The trans stays in first, the revs go past 4000 and I lift off, panicked because I think I've broken something.

I've observed this phenomenon exactly once. Since it happened, I've been driving it like a little old lady, babying it as much as I can.

I really need this car functional since I will have to use it to transport my sister home from the hospital, maybe as soon as tomorrow. Her back injuries are so severe that making the trip in my truck would be far too painful and (realistically, seriously) would threaten to fracture more vertebrae. A breakdown of this car with her in it would be even worse; the last tow truck I rode in would have definitely broken bones for my sister.

I mostly trust my mechanic shop but there have been changes recently and that trust has eroded. I figured I'd first ask people I trust who don't have a financial interest in the answers.

So, anybody seen this sort of behavior before? Any ideas what's happening?

 

[ZX9RCAM]

With it floored, I wouldn't expect it to shift till past 4000 rpm.
Probably not till after 5000rpm.

 

[Lonesome Dove]

Clogged filters do weird things. Get it serviced at a Transmission place rather than an oil service joint regardless before it goes south.

 

[benenglish]

Clogged filters do weird things. Get it serviced at a Transmission place rather than an oil service joint regardless before it goes south.

I tried to do that at ~90k miles. Since I had no documentation of the earlier service, just my memory, two shops refused the job.

I could do it myself. I've done it to multiple cars so I know how.

I am, however, a bit distracted at the moment. I may have to just baby it until other matters are handled and I can do it myself. Thanks for the input.

 

[Brains]

At wide open throttle the upshifts won't happen until approx. 6,000 rpm.

The transmission in there is a 4R70W, which is the evolution of the AOD-E, itself an evolution of the AOD. It's a well proven, well trusted, reliable unit. These are relatively simple, and not prone to sudden failures. That said there are some somewhat issues that will creep up (internal cracks and whatnot) that will over time cause issues, but they likewise gradually get worse over time vs. sudden failures like the 4R100

 

[benenglish]

With it floored, I wouldn't expect it to shift till past 4000 rpm.
Probably not till after 5000rpm.

I've done lots of imitating a drag race in every vehicle I've ever owned. This one has never gotten past ~3500, no matter how severely I accelerated.

 

[seeker_two]

Clogged filters do weird things. Get it serviced at a Transmission place rather than an oil service joint regardless before it goes south.

Agreed. And it's due for a service anyway. Just had my ATF changed & filter replaced. It smoothed things out noticeably....

 

[ZX9RCAM]

I've done lots of imitating a drag race in every vehicle I've ever owned. This one has never gotten past ~3500, no matter how severely I accelerated.

Of course I'm talking about holding it to the floor.
Gentle acceleration will shift much earlier.

 

[Gordo]

Clogged filters do weird things. Get it serviced at a Transmission place rather than an oil service joint regardless before it goes south.

This!

 

[benenglish]

At wide open throttle the upshifts won't happen until approx. 6,000 rpm.

If that's the spec, mine has always been out of spec.

However, that's good news. Very good news that tells me I might get away with just driving like an old man for the next couple of weeks.

TYVM.

 

[oldag]

So don't floor it??

 

[Gordo]

Of course I'm talking about holding it to the floor.
Gentle acceleration will shift much earlier.

Lack of pressure, change the filter.

 

[ZX9RCAM]

If that's the spec, mine has always been out of spec.

However, that's good news. Very good news that tells me I might get away with just driving like an old man for the next couple of weeks.

TYVM.

Okay, that's weird.

 

[benenglish]

Of course I'm talking about holding it to the floor.

I assumed that. I put my right foot on the floor way too much and always have.

 

[Brains]

I've done lots of imitating a drag race in every vehicle I've ever owned. This one has never gotten past ~3500, no matter how severely I accelerated.

Unless you were manually shifting, that raises an eyebrow. With the selector in D or OD, the EEC-V (computer) should be commanding WOT upshifts near the horsepower peak, which on the 4.6L is (I think) 6k. At light throttle, factory calibration in a Marquis will have it shifting ~2k. You got a brick under the pedal?

 

[Steve In Texas]

Complete Transmission fluid change out with new filters can cure automatic transmissions in some cases for a lot less than the rarely needed rebuild.

I have had luck doing just that with three transmissions. I have only had one automatic transmission where more work than the fluid filter fix above did not work.

 

[benenglish]

You got a brick under the pedal?

I'll check. I mean that.

I've had enough problems in the IT world that had insanely weird solutions to "that's not possible" problems. I know to check the most basic things so I'll wedge myself under there and make sure the pedal has full travel.

Yeah, it was a funny quip but it points to the need to cover all the bases. I appreciate the best practices reminder.

 

[ZX9RCAM]

Maybe it's not going WOT.
Could be an issue with the linkage.

 

[jrbfishn]

Have you tried to see if you can get a free diagnosis at a transmission shop? Most of the ones around here do that.

Sent from my SM-S906U using Tapatalk

 

[Sam7sf]

Ben, that’s definitely not ok for the service and mileage. I’m not sure if that year still had valve bodies or not but if it does you could have shavings from god knows what. Also your torque converter might be going out. If a transmission doesn’t have all the new chips and computers in it where the valve bodies would be, transmission problems aren’t too hard to figure out. Speaking from experience and rebuilding my own c6.