what causes a trans to shift

[bucwheat]

Hey guys,I have had my truck in the Ford dealer for two weeks now because it sometimes won't shift into second gear,well they called me Friday and said something about a bad sensor behind the turbo that builds up pressure and makes the trans shift,is this a line of BS ? I have never heard of this.They want $500 to fix this and they want to pull the transmission.

[nine6stroker]

There's been a handful of times (like 5 or 6) since I bought my truck where I begin to accelerate and it won't shift into 2nd until I completely let off the gas. Of course, a majority of those have been under WOT, so it winds up reaalllll tight

I've never heard of this sensor before either, sounds like BS to me

[bucwheat]

That is the way mine was acting,and when it won't shift into second if you push it, it will go in and out of gear really fast. But you are right when you let off the throttle most times it will shift into second.

[351fifty]

Mine would wind up good under hard accel almost red line so I let off it won't shift so I said screw it tried it again and shifted, I always thought the valve body shifted it tho

[bucwheat]

Someone on another forum told me a modulator valve changed gears in my truck and in later years the computer changed them

[351fifty]

didnt they stop using the e4od after 97? what would have it after that?

[madpogue]

About the only "sensor behind the turbo" is the exhaust back pressure sensor; IIRC, there's a tube that goes from the exhaust to it, that sometimes gets clogged. This also affects the exhaust back pressure valve (EBPV); Idunno if the PCM also uses it to control the tranny. Wouldn't surprise me if it did. Does your truck sound like there's an exhaust restriction ("whoosh" sound in exhaust) when this happens?

[STROKED_NY_023]

TAKE IT TO A REPUTABLE TRANS SHOP!!!!

Okay i think i covered this in another post about your trans as well...

Shifting in the E4OD is completely controlled by the PCM. The PCM receives signal from the Shift Solenoids which measure pressures in the primary and intermediate VB's.

As far as a "sensor" behind the turbo, i am not sure about that. I think I call BS on that one. The last E4OD i had out in my buddies OBS 7.3 didn't have any sensors behind the Turbo that i can recall, certainly nothing that is plugged into the trans...

Also the E4OD ran in the OBS trucks until 97, after that it was called the
4R100. Pretty much the same trans...

[351fifty]

so whats in the e99-03 7.3L? those are all 4r100

[96F350KID]

No sensor behind tranny. Two issues i've seen are ethier no 2nd gear shift at WOT OR 1st right to 3rd.