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Torque Converter won't unlock coming to a stop

Spokanedad

Member
Joined
March 31, 2010
Messages
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City, State
Spokane, WA
Year, Model & Trim Level
2000 Limited 4.0 SOHC 4WD
*** solved*** Torque Converter won't unlock coming to a stop

Some quick facts to do a level-set for you:

*133k miles 2000 4.0 SOHC Limited, 5R55E trans (NOT AWD), 4:10 LS
* Truck had OD light blinking, new valve body was installed and cured issues..
* After VB replacement, the trans shifted very hard 1-2, 2-3...Doesn't feel right.Everything else was working right.
* After a couple weeks the trans seemed to fall in and out of overdrive and didn't move crisply between 4th & 5th. 1-2, 2-3 still shifting hard.
*unhooked the trans lines at the cooler and pumped out the old fluid and pumped in fresh fluid.
*Leaving work yesterday and coming to a stop, the TQ converter wouldn't release from 4th gear I think and stalled the truck at the stop light. Restarted, stalled again trying to take off and third time started and took of and made it home... However it seemed to be hunting in and out of OD & 4th gear over 40 MPH.
* Additionally, the pan filter has been changed as well along with the fluid. New MAF, New IAC, plugs (Autolite), wires, no vacuum leaks I can find..

I have a pretty reputable shop I deal with and trust.. But I always want to be educated about possible easy fixes I can pursue before taking it to the Trans shop.

Any and all help would be appreciated...

-Jeff
 



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In all honesty, taking the truck to a shop is your only option. For the amount of things going on there is no easy fix at this time. Sounds like the solenoids are going bad now. Is there any banging going in and out of gears? Might also be the bands are out of adjustment or need to be replaced altogether.
 






In all honesty, taking the truck to a shop is your only option. For the amount of things going on there is no easy fix at this time. Sounds like the solenoids are going bad now. Is there any banging going in and out of gears? Might also be the bands are out of adjustment or need to be replaced altogether.

It's going in tomorrow, but in the meantime I'm trouble shooting other things that may be causing it..

And yes it shifts pretty hard from 1-2 and 2-3 and downshifts in those gears the same way... I have isolated the stalling issue down to the TQ converter not unlocking from 5th when coming to a stop and stalling the truck...

The entire Valve body was just replaced about three weeks ago with all new solenoids, ect...
 






remote possibilities

The PCM uses the TPS to determine the engine/transmission is coasting or idling. Test the TPS to make sure the voltage is around 1.0 volt when the throttle plate is closed.

The PCM uses the footbrake switch to determine when the vehicle is stopped to unlock the torque converter.
 






The PCM uses the TPS to determine the engine/transmission is coasting or idling. Test the TPS to make sure the voltage is around 1.0 volt when the throttle plate is closed.

The PCM uses the footbrake switch to determine when the vehicle is stopped to unlock the torque converter.


Thanks 2000... I've gone through a few different exercises to try and eliminate this TQ converter from staying locked... I will test the PCM's voltage tonight to make sure it's operating correctly... It's new so it should be. But it doesn't hurt to check.

On a whim, I checked the fluid level and it was low... added more to try and get it to the correct level.... Man new fluid is hard to see on the dipstick! It looks like it was a quart down. Possibly leading to the hard shifts...

The TQ converter is not locking from 5th gear any longer but it "bangs" into gear from 1-2 and 203 on both the up shift and the down shift... Could this be a pressure issue? Perhaps the EPC solenoid?
 






Thanks 2000... I've gone through a few different exercises to try and eliminate this TQ converter from staying locked... I will test the PCM's voltage tonight to make sure it's operating correctly... It's new so it should be. But it doesn't hurt to check.

On a whim, I checked the fluid level and it was low... added more to try and get it to the correct level.... Man new fluid is hard to see on the dipstick! It looks like it was a quart down. Possibly leading to the hard shifts...

The TQ converter is not locking from 5th gear any longer but it "bangs" into gear from 1-2 and 203 on both the up shift and the down shift... Could this be a pressure issue? Perhaps the EPC solenoid?

So I may have saved myself a trip to the tranny shop being on this site...

Even though I have set the levels of the fluid at least three times since I pumped out the old fluid (at the trans cooler-while adding fresh fluid).. The level was way down again. I'm not losing any fluid, I think enough air entered the system during the purge that it has taken some time to work it out.

Fluid level is spot on now and it is behaving very nicely now.

I have some firm down shifts which I believe might be some clunking coming from the out put shafts and the 1-2 & 3-3 shifts are much smoother now BUT much former than before the VB change.

Question- Do the new VB's that have the upgrades added (aka shift kits) cause the trans to shift harder into gear than the originals?
 






Valve bodies usually don't come with shift kits installed only ford updates, unless you get one from a company that puts sleeves in the valve body and new valves, like Central Valve Bodies. Still no shift kit.
Shift kits make the shifts firmer, that is their purpose, firmer, quicker shift, equals less wear.
 






Well it went away and is now back...

So I went to the tranny shop and they put a code reader on it and it was p0320.... WTF I'm thinking....

So as always I come here and start researching the p0320 code. It leaves me to multiple possibilities.. One of which is th CPS on the valve cover... So I pulled it, cleaned it and cleaned the connector and added dialectic grease...

Put it back in and it started shifting better and no stall. So if that was a weak spot I figured I would replace the sensor with a new Motorcraft piece.. Finish that and start driving again. Pulled the battery cable off and did a system reset. Do a drive test and it shifting well, in fact most of the harshness in the 1-2, 2-3 is gone. I'm thinking sweet!

Get in the truck after work and guess what... Yep it stalled at the stop light... Ok guys.. What next? By the way, did a voltage test on the TPS and it checked out fine but it should as it's brand new....

-Jeff
 






P0320

P0320 Ignition/Distributor Engine Speed Input Circuit Malfunction

The crankshaft position sensor location makes it vulnerable to road grime and water. You might disconnect/reconnect the electrical connector a couple times to clean the contacts.
 






P0320 Ignition/Distributor Engine Speed Input Circuit Malfunction

The crankshaft position sensor location makes it vulnerable to road grime and water. You might disconnect/reconnect the electrical connector a couple times to clean the contacts.

So you think I need to look at the Crankshaft position sensor vs the Camshaft position sensor I just replaced? This is the one in the coil pack right?

I am becoming totally convinced this electrical vs mechanical as it comes and goes, and I noticed that if I hit a pothole or drive on some rough roads it will reappear.

The problem only appears on the 4-1 or th 5-1 downshift when coming to a stop. Again the VB is new, MAF, TPS, plugs, wires, IAC al new. TPS tested for voltage in spec with smooth rise in voltage...

Stumped here... I will research the Crankshaft position sensor contacts 2000....
 






sensors

The camshaft position sensor only tells the PCM whether the #1 cylinder is on the compression stroke or the exhaust stroke. The crankshaft position sensor is located adjacent to the harmonic balancer at about the 7 o'clock position. It tells the PCM the location of the crankshaft which is used for fuel injection timing, ignition timing, engine speed and misfire determination.
 






The camshaft position sensor only tells the PCM whether the #1 cylinder is on the compression stroke or the exhaust stroke. The crankshaft position sensor is located adjacent to the harmonic balancer at about the 7 o'clock position. It tells the PCM the location of the crankshaft which is used for fuel injection timing, ignition timing, engine speed and misfire determination.

Alrighty then...first I will have to find it...then I will clean it an give a dose of dialectic grease.. See what happens...

So 2000... I've found it I believe. Small 2 wire connector with a c- clip? O if I have the right one which I believe I have. I had to go from under the truck tomget to it and it's really exposed to the weather, water, snow ect... I wasn't able to get the clip off but wiggled it around a bit to see what would happen... Got back in the truck and drove it.. Rit back to shifting smoothly and the harsh shifting was gone for the most part. Towards the end of the drive it started to return (harsh shifting, hunting around, feeling like it would stall)... So I will get in there and clean the plug, grease it up, ect and go from there.. Does this sensor get prone to failing because of the exposure? Should I think of replacing or just clean and see how it goes?

Thanks for all of the help!
 






Update..

Continued to trouble shoot:

Cleaned connection crankshaft position sensor-applied dialectic grease. No change

Installed new VSS switch located on rear diff-not stalling anymore but downshifts to first with an audible clank and feels like it will barely downshift in time to not stall the engine at a stop.

Not sure what else I should be looking at or doing at this point.
 






intermittent crank position sensor

An intermittent crankshaft position sensor can cause engine havoc, frequently results in no DTC, and is very difficult to isolate. Even though it has no moving parts it does fail. Some members have gotten theirs working by tapping with a screw driver handle. I suspect the electrical connection fails due to vibration, corrosion, etc. Removing and reinstalling the connector wipes the contacts and cleans them. I suggest cleaning the contacts and if you see a definite and long lasting improvement then you can assume it was the source of trouble. When I isolate to the source of a problem I usually replace the component rather than risk getting stalled by the side of the road.
 






An intermittent crankshaft position sensor can cause engine havoc, frequently results in no DTC, and is very difficult to isolate. Even though it has no moving parts it does fail. Some members have gotten theirs working by tapping with a screw driver handle. I suspect the electrical connection fails due to vibration, corrosion, etc. Removing and reinstalling the connector wipes the contacts and cleans them. I suggest cleaning the contacts and if you see a definite and long lasting improvement then you can assume it was the source of trouble. When I isolate to the source of a problem I usually replace the component rather than risk getting stalled by the side of the road.

I have zero problem replacing it if I can be sure I have isolated it... I cleaned it today and put some dialectic grease in the connector to make sure it was making a connection.

Do you think it would be best to just replace it at this point?
 






wait and see

I would cautiously drive it and see if there is a definite improvement. Your problem might reappear in a short period of driving like the last time and may have nothing to do with the crank position sensor. Often when the engine won't start due to a faulty crank sensor the Check Engine will light while the starter is cranking. Did you clear the P0320 DTC? If not, clear it and then drive a little and see if it shows up again.
 






I would cautiously drive it and see if there is a definite improvement. Your problem might reappear in a short period of driving like the last time and may have nothing to do with the crank position sensor. Often when the engine won't start due to a faulty crank sensor the Check Engine will light while the starter is cranking. Did you clear the P0320 DTC? If not, clear it and then drive a little and see if it shows up again.

It's cleared and I replaced the Crank sensor with a new sensor. What a PITA that was.... No stalling so far. But I know better than to get my hopes up..

So all new sensors, I haven't replaced the coil byt I don't think it would have an impact at this point...

The shifting is a little on the hard side 1-2, 2-3 3-4 normal and basically falls in to fifth. This has a new VB with all new solenoids.. However I crawled underneath the truck and the pan is leaking a little (tranny shop reused the cork gasket) and after reading the posts here I don't think the tech torques the VB to spec. He just zipped in the bolts with a TQ wrench.... Something definitely isn't right... I have n0 peace of mind here, I can't just drive anywhere I want because this thing may fail at any moment or it may not.

Any thoughts or next steps would be appreciated...
 






**Update**

Changed the following:
IAC, TPS, Camshaft Position Sensor, Crankshaft position Sensor, VSS (Diff), Upper and lower intake gaskets, New plugs and wires. New rebuilt VB with all new solenoids. New T-Filter, Flushed all fluid (not pressurized) out cooler lines, replaced with Mercron-V. Fluids levels perfect in trans now.

Cleaned the PCV valve (no sticking)
Adjusted Transmission bands to spec.
Slip yoke completely greased (bone dry) -Didn't stop the think in gear from 2-1...

So far the stalling has stopped, shifting is smoother and tighter particularly in 4th and 5th. The clunk into 1st when coming to a stop comes and goes. If I am on an incline or decline and approach stoplight it is virtually nonexistent. Flat road-very pronounced.

Several test drives after I reset the computer. Waiting to see if the stalling reappears.

Waiting and watching now...
 






Annnnnnnd it's back. Except this time it's hunting for gears, stalling at a stop....

I had to drive home in 2nd... It's parked and I'm out of ideas...apparently this tranny wants to die....

2000, Glacier, any ideas if you're still looking at this saga?
 



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It would appear that you have an engine problem and a trans problem, the code you pulled is for the engine, you didn't post a transmission code? The code reader that you used probably couldn't read Manufacture transmission DTC codes, not all OBD2 readers can. But you have cleared the codes and in order to pull a trans code the OD light needs to have flashed, then a code for the trans is stored.
 






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