2001 Ford Taurus Transmission shifting Rough / Hard - Inter

AB_SOOD

MEMBER
2001 FORD TAURUS
6 CYL
2WD
AUTOMATIC
63,000 MILES

My Ford Taurus 2001, with 63K is having the intermittent problem of Rough / Hard shifting. Normally the transmission shifts good, but there are days, when in bangs into each gear, especially while shifting from 1 -> 2 and 2 -> 3, and sometimes the down-shift 3 -> 2 happens with a bang(when coming to stop). It do this for few days, and gets back to normal shifting, on its own. When it shift rough, it shifts rough all the time, irrespective of the fluid being Cold or Hot. After few days the problem dis-appears completely, and it shifts normally. Again after a month or two, it ACTS up for a week, and get normal. I got the codes read for the engine and transmission, there are no codes present, and the check engine and transmission lights NOT ON. The shop says there is no problem with the sensors and solenoids, and there is something internally wrong. And I believe that if there is some mechanical problem, it will happen all the time, and not intermittently. So, I guess its some electrical problem. But all the electricals are working fine. The speedo meter doesn't flicker, and the cruis control works fine. All the electricals - radio, power windows etc works fine.

5 Replies

JGAROFALO

MECHANIC
489 POSTS

This sounds like your EPC solenoid or pressure regulator valve is sticking. This solenoid controls the hydraulic pressure within the transmisison's hydraulic system. When it fails, the pressure will default to the max pressure to protect the transmission. The absence of trouble codes indicates that it is mechanically sticking while being electrically correct.

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Tuesday, April 13th, 2021 AT 12:03 PM

AB_SOOD

MEMBER
8 POSTS

Thanks for the reply !

Should the transmission flush help in resolving the problem?

The problem started after I added Slick 50, to the transmission in Nov 2008. This was a thick solution(like Jelly), can this make the valves stick?

But the problem is intermittent. Like few days in a month, and after that it becomes normal.

I added the SeaFoam trans tune to Tranny to loosen any sticky valves(Jan 2009). And after that have driven it for 1000 miles, all short trips no more than 35 miles.
It didn't seems to help.

What else can be done to resolve it?

I appreciate your help and support.

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Tuesday, April 13th, 2021 AT 12:03 PM

JGAROFALO

MECHANIC
489 POSTS

I'm not a fan of any additives to a transmission. For the most part, there is always the potential for chemical compounds in additives reacting unfavorably with compounds in the transmission oil. Transmission flushing is another that I question. Having disassembled and overhauled MANY transmissions in my lifetime, I cannot see how anything can flush out oil contained in drums and servoes.

But. Enough on my soapbox.

You say that the slick 50 was the beginning of the problem. There is a possibility that it could have contributed to the problem. There is also the possibility that it could simply be a coincidence. I might also suggest that there could be a connection along the way that may have built up some resistance (from age or corrosion). Sometimes. All it takes is unplugging the connectors and plugging them back in to solve a pesky electrical problem. Note that the main electrical connector on the transmission is almost directly under the battery box and battery. Check this connector on the top of the transmission for corrosion. A little resistance in a connection can be enough to affect the operation of the transmission without setting a trouble code. Otherwise, the next thing to do is to try cleaning or replacing the solenoid or removing the valve body and cleaning it out.

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+1

Tuesday, April 13th, 2021 AT 12:03 PM

AB_SOOD

MEMBER
8 POSTS

Thanks for the comments.
I can check the electrical connectors, and clean them.

For the valve and solenoids. Is it a good idea if I run full can of SeaFoam Trans Tune, its known to clear any sticky valves, gum and varnish.

And after the seafoam treatment, I can drop the pan and change the filter.

My understanding is that the detergents in the new fluid, will help clean any sticky valves, and the interior of Tranny. Am I right at thinking so?

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Tuesday, April 13th, 2021 AT 12:03 PM

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