Last week, I was leaving a parking lot after driving for about 100 yards and came to a stop. I went to accellerate again and engine reved up a little like nothing and truck accellerated extremely slowly for a few seconds then there was a pop and it went. It didnt do this again that day.

Today, I came to a long line of cars at a stop sign and was slowly creeping for about 4 car lengths. After a couple car lengths, It felt like the engine released from the transmission and when I gave it a little gas it did the extremely slow accelleration then popped and went. There has been a hissing sound from under the truck for awhile now, but it seems to have gotten louder. Any ideas what this problem could be?

 

have you checked the trans. fluid level after the truck is warmed up?

 

torque converter is probly shot

 

Torque converter is probably fine. Sounds to me like the MLPS (Manual Lever Position Sensor) mounted over the selector rod, on the side of the transmission could be bad.

This sensor tells the computer where you are in terms of gear selection. If it is put into a Drive or Reverse, the computer will adjust (raise) the transmission's pump outlet pressure to engage the clutches. These sensors have a history of going bad and telling the computer your transmission is in "nuetral", when really you are in drive. If thats the case, the pump will not be putting out enough pressure to engage the clutches.

But do what Quicklook said first, and check the fluid. If the fluid is fine, and this problem continues to be intermitten like you say it is, then change out the sensor.

To change it out, you have to pull the shift linkage off by removing the nut on the end of the stud (12 or 13mm head I believe.) Once you get that off (you may have to pry a little to get it off,) then remove the 2 bolts that hold the black box to the tranny. Should be 8mm head on those. Once those are loose, pull the connector, and the sensor should slide right off.

I know Auto Zone and Advance sells these, but they won't know them as the MLPS. They will know it as a "Nuetral Safety Switch." It will be right about $50. To them, its an expensive Nuetral Safety Switch, but like most of those people, they don't know any better!

 

While we're on E4OD problems, I've got a '94 F150 also with a 4.9 and the E4OD. Recently it started to have shifting problems. Rough shifting, "stalling" like it was going into netural and generally just going spastic. It would settle down, behave just fine, then start this stuff all over again. Did the research and sounded like the classic MLPS problem. Replaced the sensor, and since the wiring connectors for both the MLPS and the tranny itself looked pretty baked, I got replacement wiring harnesses and replaced them. Stopped the shifting problems oh, for about 10 minutes and started the whole thing over again. Read some more postings and thought it could be the wiring connectors under the hood. Popped those, cleaned them, applied silicone grease and once again it stopped for a bit.

Thought it might be throwing a code or something when it was acting this way, so I got out the trusty code scanner and pulled them. It was showing a couple of codes in memory, so I cleared them, went for a drive and waited. It started slipping and slamming again, so I stopped and pulled the codes. Got a 334, vehicle speed sensor voltage too low. Replaced the speed sensor and everything was fine- for a couple of days. Now it's back to it's old tricks. Runs and shifts like a new truck for a while then BAM! I can't seem to keep it in third or fourth gear.

I'm fast approaching my wit's end. Any of you other E4OD guys out there have any ideas?

 

Id recommend that you start a new thread Webdoc, preferably in the transmission forum... but I'll do what I can here.

So now you can't keep it in third or fourth? This again actually sounds like a MLPS problem.

 

Yeah, I agree. So I take the new sensor back to O'Reillys and exchange it for another one. Check it with a DVOM before I installed it. No luck.

Great idea posting to the transmission forum. I forgot it was there. Just rejoined FTE, I was on back in the old email listserver days with my old '84; we didn't have specific forums like that!

 

I noticed that my speedo is making irratic movements when I come to a stop and even more so when in reverse comeing at slow speed. The MLPS is only 2 years old with the updated connector. It doesn't explain the hissing sound that goes away if I increase the revs a bit. Also, I have a pulsing rough idle in netrual and park. I had a MLPS code a couple years ago and it went away when I replaced it and shifting improved quite a bit. Also, lately during this time it is downshift happy, which in a way is nice because it makes it a lot more peppy. I'm thinking a new VSS is in order and go from there and do a stall test for the converter.

 

did you look at the trans. fluid level?

 

this can also be caused by a bad ground connection
or any number of sensors
check this site for great amount of info and testing procedures
www.fordfuelinjection.com

 

The hissing and irratic idle tells me you have a vaccuum leak. Check the vaccuum hose leading to the MAP sensor mounted right underneath the passenger side windshield wiper on the firewall. That is if you have a SD system. I can't remember if the 4.9's came with MAF. Nevertheless, a bad reading from the MAP sensor can make the transmission shift funny. Don't believe me? Pull the connector from it and take the truck for a drive. You want to talk about hard shifts!

A two year old MLPS could still be bad. A little bit of water can get through the connector and cause problems.

If the speedo is moving a little when you're stopped, you can pretty much rule out the VSS. Usually when those go bad, the speedometer will jump all over the place when you're moving at 45 MPH or more. Sounds to me like your PSOM could be going bad, which would cause the transmission to do funny things.

But first off, fix that vaccuum leak. Truth be known it could be causing all of your problems.

 

overfull, doesn't smell burnt.

 

I'm pretty sure it is not a vacuum leak. You can really only hear it under the truck and by the transmission. I can't hear it from the engine compartment. The MAP sensor was replaced do to a pinging problem and lean condition I was having.(which it fixed)

The irratic speedo is happening when at very slow speeds with the truck, not when stopped.

 

Handyman, what is the PSOM?

 

it is part of the gauges.

psom = programmable speedometer/odometer module