Taurus Car Club of America : Ford Taurus Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter · #1 ·
My daughter has a 2005 Taurus SE V6 flex fuel, with approximately 130,000 miles. For some time the check engine light has been on and the Ford dealer told her it was the fuel gauge unit in the tank - wanting, of course, $6 - 700 to "fix" it.

I rummaged around in here and found out about the flex fuel module, so I got one and just changed it. Light is off, fuel gauge is now working.

BUT, she says there's a "hesitation". So, I drove the car, and under normal acceleration it shifts at approximately 2500 rpm, then IMMEDIATELY downshifts and stays in the lower gear for several seconds before upshifting again. I'm not sure if it's the 1-2 shift or the 2-3 shift, but it happens at fairly low speed - 25-30 mph. It doesn't have SEVERELY every time, but it does jerk and downshift the vast majority of the time.

She took the car in and had the transmission serviced, and they found no problems, no metal, nothing. The transmission shop says there's no problem with the transmission and "hoped" it was related to the check engine light.

Question - Is this related to the hopefully now correct fuel gauge issue? Or is there some other likely problem? As I said, with the new flex fuel module, the check engine light is off and the gauge is working, but the sudden downshift is still there.

Ideas?
 

·
Premium Member
Joined
·
17,415 Posts
Hmmm interesting. I would unhook your negative battery terminal, rehook it back up after a few seconds and drive it around for a bit...let the car relearn shift points, etc. Take it for a good drive, like 50 mile drive to let the drive cycle happen. See if the light comes on...

The way the OBD-II system works ( OBD2HELP ) you may have a pending code waiting, but it hasn't popped up yet. AutoZone and the like should have a code reader on hand that can check for you...report back if you do or don't get a code :)
 

·
Registered
Joined
·
3,748 Posts
I can't think of the damn sensor. I want to say the VSS, but I'm not sure. My friend had a sensor replaced because his SHO would stall, we almost got stranded on the freeway, but had enough 'juice' to get off, and the power eventually cut off. There was weird up and down shifting too. I'm looking into it.
 

·
Registered
Joined
·
1,392 Posts
Does the speedometer bounch up and down at all? Have you tried the cruise control? It could be the vss, but when was the transmission fluid changed last, and was Mercon V atf used?
 

·
Registered
Joined
·
3,748 Posts
So, I checked with my friend. It was the VSS. Does your car completely shut off? Or just hesitates and chokes?
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #7 ·
Thanks for the replies everybody......

When I replaced the Flex fuel module I unhooked the negative battery terminal and had it off for the 15 minutes or so it took to change. So, it should have reset whatever its going to reset.

I drove it around the neighborhood, but I don't know how far she's driven since Sunday. In conversation with my wife yesterday, my daughter said she thought it was "better" (whatever that means - even after 60 years I haven't figured out how to translate wife/daughter to mechanical symptom)...

So far, the check engine light hasn't come back on, and the fuel gauge continues to work correctly.

She had the transmission serviced last month. And I confirmed they used the right fluid.

It doesn't stall or lose power or do anything other than downshift. It doesn't happen at full throttle (I presume 'cause the upshift is happening much later), only when driving "normally". It makes a normal, smooth upshift, the immediately downshifts for a few seconds, then upshifts normally again. Tach is fine, speedometer is fine. Looks like all the gauges are fine. Just jerks into a quick downshift, engine revs for a few seconds, then upshifts fine again...

It feels almost exactly as though the driver, just at the moment after it upshifted, applied enough throttle to force it to downshift and accelerate.
No hesitation, no choking, just the downshift.....
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #8 ·
OK, check engine light is still OFF after a week. Offspring has DEFINITELY driven the car well over 50 miles. It still doing what it was doing...

Upshifts normally, then instantly downshifts, and upshifts again after a few seconds.....

With no check engine light, I presume it's not throwing a code. Which means I SURE can't take it to any of the dealers around here, 'cause with not SPECIFIC code that tells them what part to change, they'll be randomly messing with every mechanical system on the car...

SO, somebody out there knows what this most likely is... And unfortunately I need to know, 'cause GUESS WHO is going to have to pay the ^%$#@ bill?
 

·
Super Moderator
Joined
·
8,623 Posts
Possible TPS problem like a dead spot? To check, use a graphing scan tool to watch TPS PID as you drive and see if there are any rapid jumps or discontinuities in TPS output. Could also monitor TPS output voltage with a DMM (key on) while opening / closing throttle to look for voltage jumps / glitches.
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #10 ·
Well, I certainly wouldn't discount the TPS, although the styles of driving when the problem occurs kinda points me away from there.......

Very, VERY, slow - my wife (think 60-year-old granny) - works fine. Upshifts and stays up. VERY little throttle

Aggressive - daughter ('nuff said) - upshifts, then jerks down, then eventually upshifts again. "normal" to fair amount of throttle.

VERY aggressive - (me) - Since it doesn't upshift 'til 5000+ rpm, it stays in the next gear. Runs fine, works fine, no problem.......

Seems like a WIDE range of intermediate settings from moderately gentle to pretty aggressive throttle will provoke the behavior.
 

·
Registered
Joined
·
53 Posts
I am watching this one too!! I have the EXACT same issue with my 04. I initially thought the problem was in the trans, but what I found is that along with this issue if you take your foot off of the pedal at the time you are experiencing this, throw it in neutral, the RPMS will fly up to 3500ish and hang there for a few. Sometimes they won't come down until I stop the car. The trans is shifting this way because of an engine issue.

I did replace the TPS, and it seemed to make the problem go away - for about 2 weeks.....now it's back. So now I am wondering if I got a punky TPS, or if there is a wiring issue.. not sure. I am going to swap the TPS (under warranty) and see what happens, if no better, I am willing to bet that I have a bad wire somewhere.
 

·
Registered
Joined
·
53 Posts
Update on mine.....Apparently I got a bad, brand new BWD (Borg Warner) TPS.....seems to be a bad lot of them out there right now from Borg. At least at O'Reillys... Warranty exchange, all better - nice solid shifts, smooth downshifts, rock solid idle... Perfect!!!

You would be amazed at what type of drivability issues come from a poor TPS signal..our bulls just give some mild nuisances to our driving...my 2004 Durango went into limp mode and shifted into 2nd gear (at 75mph on the highway mind you!!!) and refused to shift out of it. This happened on our way to Cedar Point in OH - 100 miles from home....thankfully I swapped it with a new one in podunk OH, and we only lost about 45 mins....

The symptoms can vary widely...oh yeah, in neither case did I get a CEL....
 
1 - 13 of 13 Posts
Top