Hi There , just picked up our 03 F250 7.3 SD from the tranny shop and it has some problems that I need advice on please.
In The rebuild most of the trans was upgraded and a new soliniod pac fitted.
A sonnax performance pac SC-4R100 HD and kolene steels fitted as well.
The Sonnex pac was fitted using the supplied springs with no shims .
Driving just truck only, the shifts are firm but not harsh, ( firmer than the original box ) but if we hook the fiver on behind ( 12000 Lb ) the shift from 2nd to 3rd is severe and the others are harsh .
Question time ::
1:: Have an AE scan tool but cannot find a pressure sensor option for the tranny, is there a sensor on the box that can be monitored ?
2:: Using same scan tool is there any " adaptions " that need to be cleared now tranny has been rebuilt ? or is that a Ford thing
3:: what should be the range sensor voltages during the gear changes,
at the minute they range from 1.6 - .02v
Any other advice would be great ......... thanks
Brownie

 

Well honestly that is a weird problem. I used the Sonnax performance pac SC-4R100 HD in my trans build and mine shifts hard, sometimes too hard in OD with no load. But when I am pulling 8k it actually shifts nicer unless I have my foot to the floor. Which makes me wonder what roll the TPS plays in the trans shift. But it could also be a accumulator valve hanging up. Because when installing the Sonnax accumulator valves you are to use this bore sizing tool. I didn't I just honed my accumlator bore wish I would have bought the tool. http://www.sonnax.com/system/instruc...948-09K-IN.pdf
Also are you running tunes when it does this? Have tried changing tunes to see what happens?

And I am interested to hear how you check the epc solenoid & pressure can be checked with AE ?

 

Hi There, No everything is stock standard no tunes

Am not sure about the tool , will ask the technician

 

There is no pressure sensor in the transmission.
There are no "adaptions" in the software. There is nothing to clear.
The range sensor voltage should only change when you move the shift handle. They should not be changing when the trans is shifting automatically.

The scheduling of the shift (when it shifts) and the pressure that is used to make the shift are both directly affected by the TPS.

You can only check what pressure the computer commands the EPC to produce. AE cannot check actual pressure because there is no sensor.

 

Mark thank you for the input and sharing some of your knowledge. I have noticed my harsh shifts happening when I have my foot in it and not so much when I am 3/4 throttle or less which had me wonding what the TPS signal was and if it effected shift pressure. Now if I can keep the pedal at 1/2 at the time of shift it shifts nicely. So I was thinking of installing a new TPS and if that effects the shifts.

Now as far as the EPC pressure if the computer is telling it to calulate what EPC pressure to build to. But if due to modds that pressure is actually alot higher than what the computer thinks it is??? And since you pointed out there is no sensor is there a way to put a gauge on in a pressure port and check and see if the pressure is out of spec (whatever that might be) on the high end ?

Now Brownie I too am still running stock tunes and I personal like the stock shift strategy and shift points. I just wish I could find out why every now and then the OD shifts WAY too hard. I was thinking what could cause a hard 2-3 shift and it makes me wonder if your builder used a Sonnax center support shim #36743-01 http://www.sonnax.com/system/announcement/36743-01.pdf. Because if he didn't and over torqued the feed bolt you could be getting valve body cross leaks at higher pressures or loads. Just something to throw out for you to think about.
http://www.sonnax.com/system/instruc...6743-01-IN.pdf

 

There is a pressure port on the driver's side of the trans. It is the port that is often used for a temp sender.

You can install a gauge with a 1/8" NPT thread in this port. This checks line pressure, but line pressure is controlled by EPC. I don't have the chart of acceptable pressures, I'm sure someone else will post it.

 

Mark, I have heard that the PCM learns your style of driving, and adapts the shift strategies accordingly. If this is true, could this be a reason for new rebuilds acting differently?

 

The only thing the PCM 'learns' is whether or not the 4R100 is a PTO model. When a PTO trans is found, the high idle feature is available. When using the high idle via PTO control circuits...the EPC is increased a bit.

 

No, it's not true. No Ford PCM learns driving style. The PCM with a diesel 4R100 isn't capable of learning anything having to do with shifting the transmission.

 

Good to know. I had heard that, and I am glad to have that myth dispelled.

 

Here is the chart:
Line Pressure Chart.doc

 

Sorry for delay in reply and thanks heaps for all the input .......... this forum is really great for us new guys .
The trans rebuilder is going to drop its pants and have a look to see if the correct pistons/shuttle valves have been put in the correct holes and check out the "Shim "
I will take the fiver with me so we can do a road test to see if that is the problem
Brownie

 

Please let us know what he finds or what he does to fix the problem. Hope he get's it straightened out for ya.

 

Finally got the time to reply , took back to the tranny shop and they say that they had installed the springs in the valve body that came with the kit . They took 2 of the springs out ( from the hard shifting gears ) and fitted the factory springs back in ......... end result is much smoother shifting