My sons 94 f150 w/5.0 transmission is slamming intermittently. Had it to shop and they have no idea what is wrong. I have changed the vss,tps,neutral safety and had pan dropped? Check engine light comes on and then goes off. If I unhook battery it shifts cine for about 100 miles then starts to slam again? Any ideas or help would be appreciated? Frustrating.

 

Pull codes. That transmission is controlled by the PCM.

My guess would be defective solenoid pack, but diagnosis and troubleshooting is in order.

 

Shop pulled codes and all it said was tps. Already changed that. Could I have a bad PCM?

 

Very unlikely the PCM is bad, way too early in the game to point fingers at anything. You need to check for your own codes. Re-run the Key On Engine Off (KOEO) tests and Continuous Memory display. Just because you had a code for the TPS and it was blindly changed does not mean it was the root cause or the new one is any better than the original.

 

If you already changed the TPS and still get the code you either bought a defective TPS (possible, but not likely) or you have a wiring harness problem between the PCM and the TPS. This is MUCH more likely than another bad TPS or a bad PCM.

 

Or the old TPS was actually bad but he never calibrated the TPS when he installed the new one.

 

How is the tps calibrated? Will be checking codes this weekend?

 

There is very little adjustment to them, the EEC-IV system is not the greatest for looking at live data, closed throttle is less than 1 volt WOT less than 5 volt(works just like a rheostat). As it has been said disconnect main bulkhead connector at firewall for the EEC and the TPS use a multimeter check for high resistance. I know someone will be able to provide pinout for the EEC and TPS. Check all of your grounds also.
The shifting fine after unhooking the battery comes into play with the EEC system relearning, fluid level high?

Curtis

 

EEC-IV doesn't do any learning. The improved shifting comes from clearing the failure mode by disconnecting the batteries.

 

Fluid level is ok! Will pull codes tomorrow. Just got hit with a big storm today. Thank you for all the help. will post code finding tomorrow!

 

Just did the key test not running. got codes 116,327 and 636. will do run test shortly/?

 

Just did the run test and got codes 311 & 327? any Ideas?

 

Hey there. So I had a little trouble with my trann slamming into gear. I don't know much about tps and pcm and that kinda thing but it came down to me changing the trann filter and my truck was really really picky about the level the fluid it was on. I had to be very careful to just get it just right. So I had to make sure it was on a flat surface and everything was just right in order to get mine to be right and now it shifts as gentle as can be. I know this isnt very helpful but just make sure everything is clean, if you drop the pan make sure the magnit gets clean also if you do the filter. I made sure everything was spotless

 

Thanks. That has been done. Filter fluid changed. Check engine light comes on then goes off intermittently also. Must be electrical?

 

Try warming the truck up first. Then redo the KOEO test again.

The KOER test #327 is telling you that the EGR isn't getting the correct info. Namely, the EVP sensor is out of range. It sits above the EGR valve.
#311 is dealing with the TAB/TAD solenoids. This tells me you have a vacuum leak and if you still have the old nylon lines, chances are one is cracked.
That could also be true for the nylone line running to the EGR.

KOEO codes #116 & 636 can be attributed to performing the test on a cold engine/not up to operating temperature. As noted, warm the engine for at least 10 minutes and then perform the test again. Those codes can be false and lead you to wasted money on aftermarket replacement NEW, junk parts.