TC locking when never before...

[Andylad13]

i noticed today, for the first time in 8 months since i got the truck, that on the highway at a steady 61mph, sometimes the TC would lock up and throw the rpm's up about 300rpms. i did it 3 times today, in no pattern like climbing hills or anything, it just did it. she stayed locked for about 30-40 seconds each time. i've never had it happen to me before, should i just deal with it or is something wrong. the OD light doesnt blink.

 

[Camarogenius]

If thr RPM's went up, that would mean it's unlocking, or slipping.

 

[Andylad13]

If thr RPM's went up, that would mean it's unlocking, or slipping.

ah ha! then this is now my issue...then there IS something wrong. is the tc about to go? what can i expect to happen if she fails.

 

[JwS]

If that is the only symptom I would guess your FIPL is failing, replace it before the tranny gets damaged. Same exact symptom I had on my new tranny.
JwS

 

[Andylad13]

the fipl is about 4 months old, still think i should replace it?

 

[1991 F350 Crew]

Sounds like the same problem I am having. What is the FIPL?

 

[zpd307]

a sensor off of the injector pump that controls the tranny shifts. it is like a tps for a fuel injection motor.

 

[Andylad13]

if you look on top of the motor and see the throttle lever...connected to that to the right is a plug with 3 wires coming out of it, thats the fipl. i think mine is out of adjustment...maybe.

 

[zpd307]

i dont remember what the readings should be at isle and wot, but you can check it with a voltmeter.

 

[JwS]

They can develop dead spots, so when you hit that spot it drops out, which also screws up your hydraulic pressure and can allow the tranny to slip I guess. Apparently it is to blame for alot of damaged transmissions.
But if yours is new that puts a different spin on it, maybe wiring? that could be a pain to figure out! I would look at all the plugs etc on the tranny and to the fipl. Post any new symptoms!
JwS

 

[trackspeeder]

if you look on top of the motor and see the throttle lever...connected to that to the right is a plug with 3 wires coming out of it, thats the fipl. i think mine is out of adjustment...maybe.

.50 - 1.0 volt idle. Not exceding 5.0 volts WOT.

 

[Andylad13]

yeah thats pretty much what im going with...i didnt use a multimeter for the adjustment before because i didnt like how it shifted. then i tuned it by process of elimination, and got it to shift nicely under load, so thats where i kept it. i think ill tune it to the meter now.

 

[Shadetreemechanic]

It could also be your speed sensor or tach sensor giving bad readings. Mine was doing that last month.. all month until it finally sent tranny into limp mode. I changed the tach sensor and lubed all the electrical connections and have had no problems since.

 

[LCAM-01XA]

.50 - 1.0 volt idle. Not exceding 5.0 volts WOT.

Actually the general recommendation from this board is 1.1V at idle, and no more that 4.3V at WOT, both measured with key on engine of after fully warming up, readings taken at the middle of the FIPL wires. The folks at the Diesel Stop agreed on the 1.1V idle, but say you can safely go up to 4.5V at WOT. My personal experience with the 4.5V at WOT is that it makes the part-throttle shifts very high, the thing would wind up to near 2500 before hitting next gear and I'm not even 1/4 throttle at the pedal. When my WOT was at 4.5V my idle was at like 1.35V or so, when I brought the WOT down to 4.3V my idle went down to 1.15V, and I'm pretty happy with it like that, still winds up till 3500rpms when floored, but on light throttle it upshifts at like 1800-2000 or so, much much better than before. Now how you get both 1.1 at idle and 4.5 at WOT is a complete mystery to me, the only way I see for achieving this is setting it at 1.1V idle then messing with the WOT stopper screw on the throttle bracket on the other side till the IP opens enough for the FIPL to read 4.5V - does that seems safe? I mean, is there something that can be damaged by the IP opening "too much"? Hoe does one know what to set the WOT stop screw to?

 

[oldmisterbill]

I had the same problem once -1st attempt was to clean every (I mean EVERY)connector related to the transmision.It worked so I cleaned a second time and packed all the plugs with the equivilant of dialelctric silicone.Never had a problem since then.Yupp it could also be many other places but i'd check this first.