98 Taurus: Shifting problems...

[shorod]

According to the service manual the P0708 code, if real, should result in harsh shifts.

-Rod

[mfaerber]

Right you are, I have read the same thing and it sounds just like what I have been experiencing. I may end buying a new one tomorrow, after more research.

[mfaerber]

Mini-Update: Drove the beast to work, about 15 miles city and highway; still definitely having shifting problems. Will do more research.

[mfaerber]

So, I tested my DPFE according to the instructions here: http://free-auto-repair-advice.blogs...gr-system.html

But, it turns out I forgot to turn key to RUN. So, my results are worthless and I'll have to do it again tomorrow...

Anyways, I found a couple cracks in a very short bit of rubber tubing attached to the underneath of the throttle body and attaching to a metal tube that I think extends to the firewall (could be wrong, it is long). I taped it up for now...

I also removed the EGR valve and throttle body and cleaned them with Carb Cleaner/Throttle Body Cleaner. There were not any blockages and the EGR seems to open/close/hold suction just fine.

Ran the car in the driveway for about 5 minutes, reved it once up to 3k. Before I reved it the OD light was flashing... By the time I turned the car off it was no longer flashing. The scan tool recorded two pending codes that I have never had before:

P0122 Throttle / Pedal Position Sensor / Switch A Circuit Low
P0760 Shift Solenoid C

Maybe, like with P0708, it's just something temporary because I was monkeying around with things... I'll clear the codes tomorrow before driving and update.

Also, I ordered a new PCM and will get it Wednesday. I'm hoping that it is actually bad and is causing my P0135 and P0155 (oxygen sensor heaters) problems.

[shorod]

Did you reconnect the TPS from having the throttle body off, or did you turn the key to run at some point with the TPS disconnected?

-Rod

[mfaerber]

I definitely always reconnected the TPS before putting the key in at all.

Could the TPS be one of my problems? I haven't read up on it before, but I am now.

I cleared the codes before I left the house this morning. When I arrived at work (15 miles city and highway) I had the three usual pending codes: P0135, P0155 and P0455. P0122 and P0760 did not pop up. The car did not drive any differently, still had a lot of trouble getting into the correct gears, and staying in them when it did.

EDIT
So, after reading about it, now I'm suspicious about my TPS. I'll test it tonight based on this: http://www.autozone.com/az/cds/en_us...rInfoPages.htm . The type of TPS I have is NOT adjustable.

By the way, my scan tool DOES record the "Absolute Throttle Position", it calls it "TP(%)". You can see the TP(%) in excel-chart form below the graphs that I made here: http://badsushi.net/images/livedata_graph_8sep08.gif . I couldn't say whether everything looks kosher or not...

I'm also going to inspect and test the IAC: http://www.autozone.com/az/cds/en_us...rInfoPages.htm

[mfaerber]

Final Update

The problem was the Neutral Safety Switch (aka Transmission Range Sensor). It was filled with water and leaking said water into the connector, causing erosion. The only place I could buy one was at Ford, so I did. Now the car runs like it's new.

Thank very much for your help shorod.

[shorod]

Great job, and thank you for the update! We should start a sticky with all the issues owners have found due to faulty TRS/DTRS units.

-Rod