I am really frustrated about my 94 M8 that has a gremlin running around somewhere. I have an intermittent problem that occurs only once in a while mainly when I am above 55 mph. The trans shifts out of OD and into 3rd, and then back to OD. Even if I switch off OD and try to drive in 3rd, every once in a while it will take itself out of 3rd and go into OD. At times it even seems to slip entirely out of gear momentarily. The other factor seems to be related to electrical draw because it mainly happens at night when my lights are on. This is the second trans that I have installed that has the same problem, so I doubt it is internal to the trans. This trans was installed about 8 weeks ago and ran great for about 2600 miles before the problem re-emerged. This is the same problem that the original trans had when I replaced it. The battery / charging circuit seems to be OK (no hard or sluggish starts) but I still suspect something electrical. I have quadruple checked all of the connections to the trans itself, and it does not seem to be a loose wire. It occurs on smooth highways randomly. I have tried replacing the MLPS. It does not seem possible to me that the trans has an internal problem, because most of the time it runs great and shifts great. I installed a 1998 Grand Marquis trans re-pinning the harness and replacing the lockup solenoid with the older version. Man... I really have no idea what else to look for. Any other ideas? Could a high electrical draw from the AC / stereo / lights cause these symptoms? Would Ford be able to diagnose the problem considering that it only happens once in a while?
Need Help Please - Trans Problems!!!
- Thread starter ruswin
- Start date
man I hate to suggest this....
But a goofy or misreporting TPS sensor will cause all kinds of goofy shifting problems.
Since it's a first gen, changing the TPS isn't going to be a fun job.
TPS=Throttle Position Sensor.
when it goes "stupid" it makes your PCM think your giving it more or less gas than you really are.. and will make the shift schedule do "stupid stuff".
But a goofy or misreporting TPS sensor will cause all kinds of goofy shifting problems.
Since it's a first gen, changing the TPS isn't going to be a fun job.
TPS=Throttle Position Sensor.
when it goes "stupid" it makes your PCM think your giving it more or less gas than you really are.. and will make the shift schedule do "stupid stuff".
Moes8
Dedicated LVC Member
i have yet to try replacing mine,but that sounds like a great idea,if i ever have to
thanks
Would a bad TPS actually be able to "command" the trans to disengage the OD over-ride function? A bad TPS would make sense if it was just downshifting, but when I put it in 3rd by activating the OD override, it will go back into OD on it's own and the Green indicator light for OD override turns off. I don't think a funky TPS could cause that. I would think the only thing that would disengage the OD override is the momentary switch or the computer.... 
I just drove it again today during the day for about 40 miles and it shifted fine again. Could there be a funky ground connection or something else simple to look for? I am even thinking about trying another MLPS, but I really don't think it is the problem either.
I just drove it again today during the day for about 40 miles and it shifted fine again. Could there be a funky ground connection or something else simple to look for? I am even thinking about trying another MLPS, but I really don't think it is the problem either.
chicken
SHEOOOOOOOOT
the wires to the button could be chafed, somewhat common problem
No problem - it was super easy with removing the TB.
Markviiiedrea
Speed Bump
Well if you already have a ne MLPS, try the TPS. If you don’t want to throw 40.00 away go get a few from the junk yard, I believe there the same on most fords. If it works then go get a new one.
Is the problem getting worse the more you drive the car or is it faulting out constantly?
Is the problem getting worse the more you drive the car or is it faulting out constantly?
The problem occurs VERY randomly, not very often. It did not happen for the first 2500 after I installed the used trans. Besides shifting from 4 to 3 or 3 to 4, it also seems to completely come out of gear (neutral) rarely also. That is why I have a hard time believing that it is the TPS.
What would command the trans to go into neutral except the MLPS? I have an assortment of MLPS from past projects as well as the new one I installed. I have tried installing the others, with basically the same results. This problem really sucks because it is impossible to predict when it will happen again.
What would command the trans to go into neutral except the MLPS? I have an assortment of MLPS from past projects as well as the new one I installed. I have tried installing the others, with basically the same results. This problem really sucks because it is impossible to predict when it will happen again.
a blown up or nearly blown up 1 way clutch
Would a blown one way clutch allow it to run without a problem for 50+ miles and then randomly start failing again? There is really no pattern to it, it runs great most days, then every once in a while it will happen again. I don't know squat about internal trans workings but mechanically I would think it is OK or else it would be progressively be getting worse and not allow freeway blasts at 85 mph for 20-30 minutes at a time without any problems. Hmmmmm....... 
Rich88LSC
Dedicated LVC Member
This sounds like MLPS symptoms to me. Just because it's new doesn't mean it's not bad. I would look at that or like chicken said look at the wiring.
I have 2 other MLPS that I have tried... used but they seem OK. The problem happens when either of them are installed, I guess it is possible they are all bad? I have replaced the shifter handle previously because the thumb button was broken. Is there anyway to completely eliminate the OD switch from the circuit to test if it has anything to do with that switch?
Is it at all possible that there is a charging system or electrical problem with the alternator, battery ect. I have noticed lately that when the car is first started, it cranks for 5+ seconds and does not fire usually. Releasing the key and turning it a second time and it fires right up. Could these symptoms be related? I don't remember having that problem when the trans was working perfectly. What a pain in the A@#!
Is it at all possible that there is a charging system or electrical problem with the alternator, battery ect. I have noticed lately that when the car is first started, it cranks for 5+ seconds and does not fire usually. Releasing the key and turning it a second time and it fires right up. Could these symptoms be related? I don't remember having that problem when the trans was working perfectly. What a pain in the A@#!
ripped camel
Dedicated LVC Member
Where's the tps located?
Chadly
Dedicated LVC Member
If the OD OFF light goes off too by itself, I would agree its the wires getting chafed. Thats at least something easy to check and rule it out if its not the case. I would start there.
I checked the wiring to the OD switch, it seems OK. I do not think that is the problem because when it downshifts to 3rd on it's own, the green OD over-ride light does not turn on. I am thinking it may be the TPS because feathering the throttle will sometimes cause the problem to occur. XLRVIII was the first to suggest that as being the problem. I am going to try a new one. I just want to confirm that the TPS for the 94 Mark 8 is Ford # F2AF-9B989-AA? Autozone has 2 different numbers for it, the other is wrong according to Ford.
chicken
SHEOOOOOOOOT
id only go ford, fukk auto zone!!!!!!!
Normally I'd agree... but the Motorcraft part was $78, Autozone was $35. I just got done installing it an unless it is bad out of the box, the TPS is NOT the problem. I just took it for a test drive and it is still doing the same thing.
How and why would it take itself out of OD over-ride is what I do not understand. I might still suspect the MLPS if it was not for that symptom. The wires going to the OD over-ride switch are fine. How can it drive perfectly fine one day and then like :q:q:q:qe the next? I am soooo frustrated with this car!!!! WTF?
How and why would it take itself out of OD over-ride is what I do not understand. I might still suspect the MLPS if it was not for that symptom. The wires going to the OD over-ride switch are fine. How can it drive perfectly fine one day and then like :q:q:q:qe the next? I am soooo frustrated with this car!!!! WTF?
Just a follow up... yesterday the car ran fine for the entire trip back and forth to work, 40+ miles. When I got back home, I checked the trans fluid level, it is a little bit high... could too much trans fluid cause anything like this to happen? The only thing I did to it since installing the new TPS is to remove and re-connect the battery terminals. I swear there is something going on electrically, charging system, a bad ground, alternator problems, something intermittent. I am hesitant to bring it into to Ford to diagnose because it is so intermittent, they may not find any problem while testing or driving it.
Was the engine running when you checked the fluid or was it off.
If it was running and it seemed high it probably IS high
If the engine was OFF and it seemed high it wasn't.
ALSO, you want to check, re-check the fluid level and re-check it.
each time turn the dipstick a little bit so you are very certian your getting an accurate reading and not scraping fluid off the stick, or scraping fluid off the inside of the dipstick tube.
I've seen .5 qrt differences in level depending on how I stick the dipstick tube in
Just check, check and recheck until you get "repeatable results".
If it was running and it seemed high it probably IS high
If the engine was OFF and it seemed high it wasn't.
ALSO, you want to check, re-check the fluid level and re-check it.
each time turn the dipstick a little bit so you are very certian your getting an accurate reading and not scraping fluid off the stick, or scraping fluid off the inside of the dipstick tube.
I've seen .5 qrt differences in level depending on how I stick the dipstick tube in
Just check, check and recheck until you get "repeatable results".
I have checked the fluid level and found that maybe it was a little high, I took out about 1/2 quart. It has NO EFFECT on the problem. Saturday it ran great for normal trip of about 45 miles. Then Sunday on the same trip, it kept having the same problem. I am noticing now that it is not only going from 4th to 3rd, but also 4th to 2nd occasionally. It happens most frequently as soon as it shifts from 3rd to 4th and the torque converter solenoid locks up. I am beginning to suspect something going on with either the TC or a solenoid / wiring issue with it. When I installed the 1998 trans in my 1994, I did change out the TC solenoid and modify the connector to fit onto the newer style wiring "harness" inside the 1998 trans. Any chance that is screwing up? What are the chances of Ford being able to test and find the "problem" if I take it into them? Can they check all of the sensors and solenoids for proper operation?
"maybe" a goofy connection to one or both of the shift solenoids?
only way to tell would be to pull the pan and check/reseat the connectors.
could have it scanned, but if the problem isn't occuring they might not find anything, you'd have to scan it while the issue was occuring.
They have a "test" harness they can put on teh trans and command each of the solenoids, but if it's a loose connector it may or may not show anything.
might be time to drop the pan and check it out.
could be the fluid is moving something around causing the intermittant problem.
only way to tell would be to pull the pan and check/reseat the connectors.
could have it scanned, but if the problem isn't occuring they might not find anything, you'd have to scan it while the issue was occuring.
They have a "test" harness they can put on teh trans and command each of the solenoids, but if it's a loose connector it may or may not show anything.
might be time to drop the pan and check it out.
could be the fluid is moving something around causing the intermittant problem.
If nothing else... I am going to end up knowing a lot more than I ever wanted to about the 4rW70!!!! Yeah it sure does seem 99% likely that is is electrical, solenoid connection possibly. What if the TC lockup solenoid was just cutting in and out, do they go bad? It really now feels related to the 4th gear and / or the lockup solenoid....