98 Taurus: Shifting problems...

[mfaerber]

1998 Ford Taurus Station Wagon - V6 3.0L DOHC - 130k miles

I have a shifting problem...

(Full disclosure: I am currently trying to remedy P0135, P0155 and P0455. I have been told that my shifting problem should not be related to P0135 or P0155, but I'm not sure about P0455... I've done a lot of things, including replacing most of the vacuum hoses, replaced the PCV valve, replaced the fuel pressure regulator, cleaned the MAF sensor with MAF sensor spray, replaced the spark plugs. The engine had a tune up a few months ago, engine oil is good.).

THE PROBLEM

While driving I immediately notice that the car does not shift when it should. If I'm doing 25mph the rpms are at like 2k. If I'm at 60mph the rpms are around 4.5k. Now, this action does fluctuate. If I am at 60mph and I put on the cruise control, the rpms may eventually drop from 4.5k to a resonable 2.5-3k. But, a couple minutes later, the rpms might shoot up again. Some drives are worse than others. The engine oil temperature gauge does not change from it's ideal position.

Initially, I had this problem about 2 months ago and I took it to the shop where they did a bunch of things including a transmission fluid flush. They told me straight up that if the transmission is dying, that a flush would ensure it's rapid death, but that flushes are kind of necessary... So I had them do it. Since then I have been trying to fix everything that is throwing the current codes. It has been a month and half with no shifting problems and now the shifting problems are back.

Maybe my tranmission fluid is too high. It is almost an inch above the full line. I'll test the level again tomorrow though, because the criteria for reading the level are pretty specific (for example, my car is parked on a slope).

If it was really a transmission problem, I would think that I would get a code for the transmission... so that's where I need some veteran advice. I have a pretty good scan tool and a multimeter.

Thank you in advance!

[shorod]

I don't have much experience with transmissions, so I cannot comment on that to much degree. However I do know that overfull transmissions can exhibit some pretty odd behavior, so I agree with you that you need to make sure the fluid level is correct. With the car level and the engine up to operating temperature, you are supposed to check the transmission fluid level wtih the car idling in Park or Neutral. If you are checking the fluid level with the car not running, it will appear to be about an inch over full usually.

For shift timing issues, the factory service manual points to diagnostic routines 212 (electrical) and 312 (hydraulic). The items to check for section 212 are: Electrical Inputs/Outputs, vehicle wiring harnesses, powertrain control module, shift solenoids, Digital Transmission Range, Torque Converter Clutch, Turbine Shaft Speed, and Transmission Fluid Temperature sensors, Throttle Position, Vehicle Speed Sensor, Engine Coolant Temperature, Intake Air Temperature, and Mass Air Flow sensor.

If your scan tool has a datastream mode, you may be able to monitor many of these sensors real time to determine if they are working and reasonable while the car is acting up.

For hydraulic diagnosis, the manual suggests first checking the fluid for improper level.

Main Control Valve Body:

• Bolts out of torque specification
• Gaskets - damaged, off location
• Valves, accumulators, seals, clips, intermediate clutch shuttle valve - stuck, damaged

Vehicle Speed Input:

• Speedometer Gear - drive damaged
• Speedometer Gear - driven gear and shaft assembly
• Differential assembly - damaged or missing
• Speedometer drive gear - damaged

Torque Converter Clutch (TCC): Refer to Routine 342

• Shift concern: 1-2 Shift - Routine 220/320
• Shift concern: 2-3 Shift - Routine 221/321
• Shift concern: 3-4 Shift - Routine 222/322
• Shift concern: 4-3 Shift - Routine 223/323
• Shift concern: 3-2 Shift - Routine 224/324
• Shift concern: 2-1 Shift - Routine 225/325

-Rod

[mfaerber]

I recently recorded data on my scan tool while the car was acting up and graphed it, click here to see it.

[shorod]

Any idea what your sample rate is, specifically for the O2 sensor data? It would appear from the plot that the B2S1 sensor is quite slow to respond, but that could be due to aliasing because of the sample rate.

All your throttle position numbers are pretty low. Were you gently accelerating as these plots would imply, or is your TPS maybe not responding appropriately?

Any idea where within those plots the car was acting up? Were you just datalogging, or does your scan tool have a "trigger" feature where you press a key to start the datalogging process. Often the scan tools will record 20 seconds prior to the trigger as well as 20 seconds after the trigger.

Other than the B2S1 data, nothing stands out as being abnormal. The fuel trims are a bit higher than desired, but not in the area that anyone would say you need to be concerned about them. I don't believe that either of these would impact shifting anyway though.

-Rod

[mfaerber]

Yes, I ALWAYS accelerate slowly. And I have been particularly gentle with the car since this started.

If you are looking at the graph, any time the RPMs got high, that is when the car was acting up. In this case I did not use the "trigger" mode. I told it to start recording manually, once the car started acting up.

I should have put the RPMs and the MPH plots on the same graph... But look at those two anyways. If the car was having no problems, then the RPMs would have NEVER been above, say, 2.5k (in this case, I never went above 45, but I did go up a hill at a redlight, so that could have brought the rpms to 2.5k naturally).

Check this out, I recently learned about the "throtlle body". I took it apart and to me at least, it does not look good:



Note that there is not a rubber throttle body gasket. According the autozone repair guide, there should be...

EDIT: I take it back, the top photo shoes the gasket. For some odd reason the gasket is shiny and looks like metal...

[mfaerber]

I don't know what the sample rate it, because I don't know what that means, I'll look it up.

Freeze Frame:
DTCFRZF P0155
FUELSYS1 CL
FUELSYS2 N/A
LOAD_PCT(%) 39.2
ETC(°F) 189
SHRTFT1(%) -0.8
LONGFT1(%) -4.7
SHRTFT2(%) 2.3
LONGFT2(%) -4.7
RPM(/min) 1742
VSS(mph) 43

[shorod]

Interesting, that freeze frame data is for a code P0155 which is a code for the B2S1 heater circuit. That may explain why the B2S1 data seemed slow to respond as I mentioned in post #4 above.

From your description, it sounds like you may be experiencing a misfire. Maybe your PCM is telling the transmission to downshift or hold lower gears to compensate for the misfiring engine and load.

The code P0135 that you've also encountered is for the B1S1 heater circuit, so you could have a couple of O2 sensors that are faulty, or a problem in the wiring for them. This could contribute to the misfire or driveability issues. I'd suggest you fix the source of these codes before worrying too much about a potential transmission issue.

-Rod

[mfaerber]

I have been dealing with the o2 heaters on another website. From the suggestions of those fine people I have done extensive testing in regards to the O2 sensors. In the end, the conclusion seems to point towards something wrong with the PCM. I took the PCM apart today, and though I am barely a novice, the inside of it looks great. Nothing is burned or melted. So, I wanted to search yet again for another culprit before buying a new PCM (or used one).

The last test I did on the PCM was an ohms test on the pins respondible for the O2 heaters (with the wireing harness detached). Three of the pins read 0ohms and the fourth read 336Kohms.

All four oxygen sensors are no more than 2 months old.

EDIT:
I cleaned all of the gunk off of everything with a dry paper towel and q-tips (I know it would be best if I had throttle body cleaner...). I then drove around a few miles at low speeds and everything seemed perfect, for the first time all week. Of course, I need to do some highway driving to confirm.

From just those couple miles to pending codes, P0135 and P0155 cropped up. Seems to me that P0455 is usually slower to pop up, but I could be wrong. I'll do more driving tomorrow and continue researching.

[mfaerber]

For what it's worth: I drove the car for maybe 10 miles, got up to 45mph. The shifting problem did not arise at all, the car felt perfect. Still too early to be reassured, but whatever. P0135 and P0155 popped up as stored codes.

Freezeframe:
DTCFRZF P0155
FUELSYS1 CL
FUELSYS2 N/A
LOAD_PCT(%) 58.8
ETC(°C) 190
SHRTFT1(%) -5.5
LONGFT1(%) 0.0
SHRTFT2(%) -7.0
LONGFT2(%) 0.0
RPM(/min) 2201
VSS(km/h) 12

[shorod]

The pictures in your post #5 above didn't show up for me until today. Interesting.

The TB gasket in the picture looks correct. The carbon in it and in the milled passages of the TB are from the EGR system. Those passages go to (actually come from) the EGR valve and could lead to driveability issues if they're as plugged as they appear to be from the picture.

You really should consider picking up a couple of cans of throttle body cleaner (I've had the best luck with STP Throttle Body Cleaner), remove the EGR valve, and spray out those passages with the cleaner as well as letting the EGR valve section (not the entire valve) soak with the cleaner. When the passage is clean, the cleaner should flow all the way from the TB to the EGR mounting location.

I'm not sure that would fix your EVAP code, but could potentially help your misfire (which is what I think you are feeling as a transmission issue). It could also help get the STFT numbers closer to zero.

When you had the PCM disconnected, did you also check the wires from the PCM harness to the O2 sensors to make sure there were no opens or shorts to power and ground? How were you testing the resistance of the PCM pins for the O2 sensors, were you testing between the pin and case (ground)?

-Rod

[mfaerber]

About the photo... that's very strange...

Yes, I'll definitely get some official cleaner today. I'll be flippen ecstatic if that is all it takes to fix my "shifting" problem.

I tested the pins by putting one probe lead on a grounding bolt on the cars chassis and the other probe lead on a pin. I have not followed the wires to each O2 sensor, basically because there are a lot of fricken wires and they all jumble together at one point. What I have done is remove the plastic covers to all of the wire bundles to check for obvious damage. Regardless, I cannot find exactly where I did it in the thread, but I'm quite positive that I successfully checked each O2 sensor heater wire using my multimeter (I've done so many tests...) and wire damage was then ruled out. Everyone has been suspicious about wire damage.

[shorod]

So three of the 4 O2 sensor pins on the PCM read a dead short (0 ohms) to ground!?! That's shouldn't be the case.

-Rod

[mfaerber]

Hey!

I found where the heater grounds attach the chassis and that whole assemble was VERY dusty! So I unscrewed it all, scrubbed all the metal with a wire brush and diet coke, cleaned the surrounding area and put it back. I'll know by the end of the day tomorrow if that was the culprit.

[mfaerber]

Ok...

Drove maybe 3 miles and the CEL came on after about the first (very usual, it usually takes 20 miles). During that drive the car was not shifting too great, but that could be symptomatic of what it normally does when the battery/PCM is disconnected. Erased the codes (P0135 & P0155). Parked the car for about a half hour. Drove home about 3 miles.

CEL did not come back on, but there are pending codes and freeze frame data:

Pending Codes:
P0708 Transmission Range Sensor A Circuit High
P0135 O2 Sensor Heater Circuit Bank 1 Sensor 1
P0155 O2 Sensor Heater Circuit Bank 2 Sensor 1

View Freeze Frame
DTCFRZF P0155
FUELSYS1 CL
FUELSYS2 N/A
LOAD_PCT(%) 32.2
ETC(°F) 190
SHRTFT1(%) -0.8
LONGFT1(%) 0.8
SHRTFT2(%) 3.1
LONGFT2(%) 0.0
RPM(/min) 705
VSS(mph) 0

I've never had P0708, I'm going to research it now, but maybe it's a result of me monkeying around with stuff today? One of the things I did for the first time was remove the EGR to make sure it wasn't blocked up. It had a thin layer of black powder in it, but no blockage.

AND

When I was sitting in my driveway, with the car running, at the end of my trips, the OD Off light started flashing. I pressed the OD button repeatedly, to no effect. The OD light has flashed in the past, I have neglected to mention that because it is rare.

[mfaerber]

So, I'm learning about the DPFE sensor. That seems to fit the bill. I visually inspected it tonight and the hoses look fine at least... It's the original metal one.