2000 F150, V6, 103,000 miles (Getting No Codes)

I had the Tranny replaced about 60,000 miles ago.

I've had the transmission shop look at the tranny and they say it's working fine. They say i have an engine problem.

Basically the trans shifts really hard when i first start the truck. If I let it warm up before shifting into drive it won't shift hard. If I don't let it warm up and just shift right away it slams into gear.

Also after it heats up or it's really hot outside the 1-2 shifts hard sometimes. Other times it shifts fine. Strange.

When I gun it and it's warm it will hang and not shift into gear for a second kinda like it's not understanding when to shift right.

If I'm on the freeway and I gun it sometimes not always it will rev high then down shift into all the higher gears kinda quick.

I've done so much reading I'm kinda sick and can't seem to pinpoint what the problem might be. Most of the time it shifts fine just happens at different times.

I've come to the realization that if it's not the tranny, been to 2 shops, I guess it must be the engine.

Some of the things I've been reading are, TPS sensor, EGR valve, reflash PCM, PFE sensor, maybe vacuum hose.

I don't really want to replace all these to trouble shoot so i came to ask the experts.

If anyone has any suggestions or similar problems with success's I would appreciate some help.

After the hard shift in the mourning all is good when it's cold, seems to happen alot more when it's hot outside.

And if you think it's still the tranny let me know.


Thanks,
Chris

 

try adding 60% lucas trans fluid it helped my 1989 f-150 with 5 speed manual

 

Good grief! He's got an AUTOMATIC!!!!

Chris,

I'd suggest checking the 1-2 accumulator spring first. It's the most likely possibility of the mechanical faults. If that doesn't pan out, things will get more complicated for the diagnosis. I'd probably start by monitoring (via the OBDII port) the output of the DTR sensor and the PCM-generated solenoid control signals to see if the PCM is properly controlling EPC pressure and is properly commanding the solenoids based upon the position of the shift lever. I'd also plug in a hydraulic pressure tester to monitor the EPC line pressure to see if it's jumping when the symptoms occur.

As for the suggestion that it might be the engine, unless the idle speed is way too high, you shouldn't get a harsh initial engagement just by putting the transmission into gear nor would you get harsh upshifts. However, if the EPC pressure were to intermittently max out, you would get those symptoms.

My interest would be in evaluating the EPC solenoid circuit as controlled by the PCM.

 

sho89, sounds like your a good expert to ask, i have a 02 blackwood with 4r100 trans. when hard acceleration (75%+ throttle) it will shift way late, you can tell when its going to happen and if you let up it will stay at the current rpm then finally up shift harshly. shifts so hard the belt will chirp. under normal opperation its fine, well for the most part. im not a transmission expert, diagnostics in this area is nowhere near my strong suit. any help would be awesome thanks!!

 

in my experience, the first thing to do in all such cases is replace the trans fluid and filter... it may be worth it to pay for a complete flush.
if it works, and it often does, it's the cheapest, fastest fix. if it doesn't, you're out the cost of the fluid and labor.
it's surprising how often this works.

 

And I can tell you which program is a good virus protection for a PC. Just like what you said, it may be good information, but both your post and what I just said are completely meaningless in this thread.

It sounds to me like the engine is down on power. The PCM controls the shifts based on what torque the engine should be making. If it is making less torque than it should the pressures will be too high and the shifts will slam. Low torque will also make you press the pedal further to get acceleration, which delays the shifts. Fix the engine and most likely the trans will be fine. Never attempt to fix a trans problem when there is an engine problem.

 

Mark has likely forgotten more about transmissions than I'll ever learn. I'll defer to him. My specialty happens to be electronic control systems in electro-mechanical, optical and a bit of hydraulic systems.