used SHO, new problem

FORD TAURUS
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FD946
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I am a pretty well educated shade tree mechanic, have been wreching on cars since I could walk, and I am also a part time parts guy for the local parts store. I have recently purchased a 1993 Ford Taurus SHO 3.2 ATX and the car has a few problems that I believe are related to the Vehicle Speed Sensor. First of all, while driving at any speed, the assist form the power steering changes and causes what feels like a jerking in the steering wheel. Secondly, the trans holds gears until about 3000 rpm before shifting and downshifts rough when coming to a stoplight. Third, when at cruising speed, the trans does no downshift under heavy throttle. Fourth, the O/D cancel switch seems to do nothing. And finally, when the car fully warms up, it tends to stall when coming to a stop, almost like the Torque Converter Clutch is staying engaged, that is if it has one. Idle quality also seems to be affected after warmup, with the idle surging between 500 and 900 rpm, no matter what gear is selected from Park to 1st.
Any help with this would be greatly appreciated.
Apr 19, 2007 at 2:37 PM
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MERLIN2021
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if the vss was ng the speedometer would most likly also be affected? as for downshifting, the detent cable is either broken or out of adjustment. Any way to tell if a shift kit was installed? the idle could be the IAC. I repeat I don't think it's VSS
Apr 19, 2007 at 3:21 PM
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BIGNICK
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I agree with the last post, could you have a stall converter on your car? Also, is it shifting gears when it feels like the steering wheel jerks? Could be a loose motor mount, Taurus and Sables are notorious for busted engine mounts.
Apr 19, 2007 at 3:47 PM
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FD946
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I appreciate all of the input! Let's see...as for mileage, it does infact have 150,000 miles on it. The steering issue is not shift related as it happens at low speed and cruising speed, shifting or not. I contacted the previous owner and he said that it had a shift kit installed, but he too agreed that it should not be "hammering" into gear. I had no clue that they even made a shift kit for a V6 sedan. I also did not mention on here that I replaced the TPS to no avail. I back probed it and it is getting sufficient voltage and sending out the correct signal. I had also considered the IAC Valve, but I also probed it and found good voltage and ground. I performed a diagnostic scan on it today and received a multitude of codes in the memory and KOER areas, but no faults in the KOEO. The ones that concern me the most are MAF volts too high, MAF volts too low, and no signal from the VSS which again points back to my original thinking. I did also consider the MAF, but I checked the resistance, cleaned it, and it is good. I was also told that a faulty MAF would cause a rich condition, but I also received codes for lean mixture in bank 1 and 2. This car absolutely boggles my mind. My hat is off to the engineers at Ford and Yahmaha for coming up with a technical masterpiece that we call SHO. I also aquired the use of a Ford shop manual for the Taurus, including the SHO, and it made mention of thepressure control solenoid in the trans, AKA the EPC. But anyway, I found procedures and specs for testing the various sensors, and I will let you all know what I come up with. Thanks once again!
Apr 19, 2007 at 8:48 PM
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FD946
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[quote:617695a6f1="merlin2021"]if the vss was ng the speedometer would most likly also be affected? as for downshifting, the detent cable is either broken or out of adjustment. Any way to tell if a shift kit was installed? the idle could be the IAC. I repeat I don't think it's VSS[/quote:617695a6f1]


Actually, according to Ford...No, it would not be affected. The speedo in these cars is cable driven, and the VSS piggy backs off of the cable and sends a signal to the PCM and the Speed Control Module (AKA cruise control). If the VSS on this car is faulty, the cruise will not work, or the speed may wander if the problem is intermittent. It may also affect other things such as shift timing and firmness, and anything else the is vehicle speed related...I.E. Variable Assist Power Steering. That is what I have gathered so far from the 1000 page plus Ford shop manual.
Apr 19, 2007 at 8:54 PM