Looking For Advice for next step

[abeauvais]

Hello All,

Ive been working on this 1998 ford ranger 4.0 4x4 with a possible transmission problem. The problem start with the truck have error code P0741 and so I started with the normal fixes.

1. I replace both the OSS sensor and the VSS sensor
2. Drop the pan change the filter, fluid, and the TSS solenoid. The fluid was pretty clean, some shinnys but no bit shavings or brass in the fluid. Pretty normal amount of materiel in the pan.
3. tighten the overdrive band just because

Now I've been driving around with my scan tool hook up and I am starting to get confuse, so let me lay it out and see what people think before I go deeper.

The Torque convert will lock up sometimes, when it does lock up it doesnt slip one bit! (this makes me think the TQ is working) Other time it will go to 98% on the tq lockup command and it will say it is slipping around 200 - 300 rpms then it will reattempt many time and then throw the P0741 code again. Now when the TQ locks i could be driving down the highway for like 30 mins and it works just fine. All the gear work and reverse has no delay at all or slip. I thought temp was affecting this but it appears that is not the case. I didn't noticed that flooring the truck will more than likely lock up the transmission TQ, also the temp of the tranny never got over 165 degrees. Also the RPM gauge does like to bounce around but the engine doesnt sound like it is following what the gauge say. The PCM also appears to read kinda slow at times, not sure if this a issue. I did look at the PCM and it look pretty darn clean.

So abasically I am trying to figure out if this truck needs one of the following: Torque converter, PCM, other electrical part / grounds, Valve body, or a whole new transmission. I really don't think its the Torque converter since when it does work, it works just fine. Also I feel like the internal of the transmission its self is fine since all the gear work just fine. I am learning electrical or Valve body but before throwing parts at it I would like some input. Please feel free to ask for me info, Ive been monitor man things and I just can't put my finger on it yet.

 

[franklin2]

Not sure on the Fords, but I have been several rounds on different types of GM automatics. GM got the brainy idea to not fully lock up the torque converter, but instead put some super duper clutch material in the converter and then sometimes let it intentionally slip. I guess this gave them another "virtual gear". So the apply solenoid in the valve body was modulated or pulsed back and forth many times to vary the lock up pressure. Problem is, the valve body is only made out of aluminum, and it wears out after years of the spool vibrating back and forth. Then you do not get enough clutch apply pressure and you get the slip code.

I am not sure Fords had this problem. What you do on the GM's is put a very heavy spring in front of the modulation valve, so it stays still and gives full pressure, and it cures the problem. On some of them you have to sleeve the valve body to get it to quit leaking by and losing pressure.

 

[abeauvais]

I wondering then is its my best bet to drop the valve body and inspect it. I see that valve bodies are about $250 issue fully rebuilt. These ranger apparently do that intentionally slip I believe. I normal just work on diesel 7.3 4r100's which have a clear night and day Torque converter lock up.

 

[rusty ol ranger]

Not sure on the Fords, but I have been several rounds on different types of GM automatics. GM got the brainy idea to not fully lock up the torque converter, but instead put some super duper clutch material in the converter and then sometimes let it intentionally slip. I guess this gave them another "virtual gear". So the apply solenoid in the valve body was modulated or pulsed back and forth many times to vary the lock up pressure. Problem is, the valve body is only made out of aluminum, and it wears out after years of the spool vibrating back and forth. Then you do not get enough clutch apply pressure and you get the slip code.

I am not sure Fords had this problem. What you do on the GM's is put a very heavy spring in front of the modulation valve, so it stays still and gives full pressure, and it cures the problem. On some of them you have to sleeve the valve body to get it to quit leaking by and losing pressure.

Ford does alot of stupid shit but i dont believe that was one of them

 

[abeauvais]

That being said, would my best bet still be to remove the valve body and inspect it for scoring and or stuck valves. also I guess look at the gasket itself to see if its damaged too.