About 2 weeks ago, I started my 93 F150 5.0 E40D and the CEL came on. The engine would run fine except for a stumble just off idle. So I pulled away to head home and noticed that the engine would periodically stumble at speed - not bad but enought to get my attention. then I noticed that the tranny could not seem to find the right gear - it went in and out of overdrive at speed.

I had this exact thing happen 4 or 5 years ago and the cure was the TPS. The technician told me the TPS was one of the inputs into the gear selection logic. So I think the TPS has failed again and take it to a dealer to get it scanned (this was before I learned I could scan it myslef with a wire.)

I picked the truck up today and the dealer said the TPS and EVP were indicating as bad.

But he said the tranny had been overheating and the fluid was black and needed replacing. (Actually, he said it wasn't worth replacing and that I need to think about a new truck.)

So I told him I'd have to think about that and paid him for his time and left. Ironically, on the way home, the truck ran fine - obviously the TPS problem is intermittent and the tranny shifted normally.

So my question is does his diagnosis make sense or was he trying to sell me a new truck?

I don't doubt the TPS and EVP codes - I can replace those myself. But I am questioning the transmission diagnosis.

Aside from the infamous shuddering in OD, the E40D has been bulletproof in this truck.

 

First thing I'd do is take a look at the fluid. If it's as bad as he said, then you may be do for a rebuild. Tranny fluid is the lifeblood of an automatic and if the fluid is burnt, then the tranny won't last long. Check it and if it needs it have it flushed. Drop the pan and install a new filter and see what happens.

 

I looked at the fluid on the dipstick and it looked light brown - kind of like motor oil. (And before I have to read any wise-cracks, I'm sure it was the tranny dipstick and not the crankcase. ) I can't remember if it was red or brown going in...

I made an appointment for a tranny flush tomorrow - I'll see what they say.

 

make sure to drain the convertor.

define tranny flush with them.

it is: drop pan replace filter, use ford filter if possible, drain convertor, power flush the lines and radiator trans. cooler, refill with good quality fluid.

also reset your computer.

 

If you caught it in time you're transmission is fine. The fluid is burnt from the torque converter locking and unlocking (the feeling of it going in and out of OD) causing excessive heat.

 

pfogle hit it right on the head.

if caught in time trans. can be saved.

 

Good to know.

I can fix the sensors myself for $50 - the transmission was fine until the sensors went and I didn't drive it more than 20 miles when it started acting up.

I just cannot believe that the TPS and tranny would both go at once...

 

if it was me, i would have a shop change the trans. fluid, not the dealer.

they seem to want to put you in a new truck.

also, i would get the trans. fluid done before i get a tps.

change fluid and clear computer.

than see what is what.

 

Your TPS and tranny didn't start acting up all of a sudden, just your TPS. The tranny uses information from the TPS to determine line pressure and how firm the shifts should be. For instance, if your accelerating with low throttle, the transmission will sense this from the TPS, thus allowing a softer shift. If you're hard into the pedal, the tranny will sense this via the TPS, and will make a firmer shift.

And if your fluid is that bad, please change it yesterday! Flush it ALL out.

 

Thanks, Handyman

What IS the best way to change the oil? Drop the pan or let a shop do the machine flush or both?

 

" I picked the truck up today and the dealer said the TPS and EVP were indicating as bad."

These are the two sensors that use the 5-Volt supply from the PCM so I would check your 5-Volt supply. You said it comes and goes and that sounds like Caps in the 5-Volt supply.

Also check your two sensors with an analog VOM not a DVM on the ohm scale.

 

Well I flushed the transmission and it ran great for a month or so.

Today, the CEL came on again and I pulled out the jumper after I got home.

KOEO code was 334 - DPFE or EVP > 0.67 v

CM codes were:

122 - TPS intermittently below 0.6 v
332 - EGR open not detected
334 - DPFE or EVP > 0.67 v

Subford - can you give me more info on the 5V supply? Can the caps be replaced separately?

 

Yes the caps can be replaced separately.
Here is a link to tell you how. In the link they are talking about a computer (EEC) from another auto manufacturer and the caps are the wrong value but the principle is the same.

http://www.tmo.com/howto/ecu1g/caps.htm

Here is a diagram of a Ford EEC 5 Volt supply, it may or may not be like yours. Just replace the caps with the same values that you take out.

http://i54.photobucket.com/albums/g9...VoltSupply.gif

 

subford - thanks for the info.

I went out today and hooked a meter up to the TPS and sure enough, it had a big dead spot in it. While I was playing with it, it dead spot went away - I couldn't make it fail. Hooked everything back up and the truck ran fine.

So I guess a new TPS is in order.

Can anyone point me to a post on how to replace this? Looks like the throttle body has to be pulled - true?

If so, does the TB gasket need replacing or can I reuse it?

Any other non-obvious parts I'm going to need for this project?

Thanks
Rob

 

Have a rag ready to catch some of the coolant when you take the Throttle Body Heater hoses off or drain a little bit out. True I would replace it.If the hoses are coolant hoses are old you might think about replacing them.
You could clean the IAC while you are there but do not clean the throttle body.

EDIT:
By the way the hardest part of the job is getting the two screws out of the TPS, they are loc-tite-ed. If they are button heads I use a small pair of vice-grips to break them loose as a Phillips screwdriver will just round them out.