Ford AX4N: Doesn't have line pressure sensor?

A forum for discussing applications and implementations of the MegaShift transmission controller code for the GPIO from B&G. This can control up to 8-speeds and 6 shift solenoids (plus a 16x9 table for controlling a PWM line pressure valve). It has manual and fully automatic modes (16x9 load x speed table), with under and over rev-limit protection, and full data logging of all inputs and outputs (among many other abilities). A TransStim to test your completed board is also available.
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sporqster
Posts: 3
Joined: Tue Feb 28, 2012 3:25 pm

Ford AX4N: Doesn't have line pressure sensor?

Post by sporqster »

Does anyone here know stuff about Ford trannys? From the service manual, I see nothing about a line pressure sensor as an input to the factory ECU, but it does have a line pressure control solenoid, leading me to believe that there has to be one(?).

Entire list of inputs from the service manual. Each of these I have identified wires for, or have determined that I don't need for the megashift:

INPUT SENSORS Air Conditioning Clutch (A/C Clutch) Ain't got, don't need
Brake On/Off (BOO) Switch got it
Crankshaft Position (CKP) Sensor & Electronic Ignition (EI) got it
Intake Air Temperature (IAT) Sensor got it
Mass Air Flow (MAF) Sensor don't need
Indicator Light (TCIL) don't need
Transmission Fluid Temperature (TFT) Sensor got it
Throttle Position (TP) Sensor got it
Transmission Range (TR) Sensor got it
Turbine Shaft Speed (TSS) Sensor got it
Vehicle Speed Sensor (VSS) got it

Didn't see anything about a line pressure sensor. Didn't find such a thing on the factory wiring diagram either. I guess the Ford ECU just doesn't need it? Is it using temperature to approximate pressure? Hmm. If yes, can the MegaShift be configured to do the same?

Has anyone got a MegaShift running on an AX4N or similar Ford tranny and want to let me copy their homework?
Bernard Fife
Posts: 1696
Joined: Fri Apr 04, 2008 1:28 pm

Re: Ford AX4N: Doesn't have line pressure sensor?

Post by Bernard Fife »

sporqster,

Most trans don't have a line pressure sensor. However, MShift gives you the option to add one externally so that you can set the line pressure pulse width modulated output to mirror the factory line pressure PSI specifications when tuning the line pressure table. It isn't absolutely required though, and someone who was careful and observant could do much the same by judging the amount of 'slip' in the transmission.

The default unit is here: http://www.msgpio.com/manuals/mshift/wiring.html#lpsens , as is a guide for using it with a 4L60E (for other trans you will have to figure out how to do this).

However, there are cheaper sensors on eBay, see: viewtopic.php?f=4&t=315 I can't vouch for how well they work, but they seem like they ought to be okay. I will get some soon and try them.

Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw
sporqster
Posts: 3
Joined: Tue Feb 28, 2012 3:25 pm

Re: Ford AX4N: Doesn't have line pressure sensor?

Post by sporqster »

Thanks! I somehow knew it couldn't be as easy as a weekend wiring exercise ;-)
bondango
Posts: 16
Joined: Thu Jul 05, 2012 2:15 pm

Re: Ford AX4N: Doesn't have line pressure sensor?

Post by bondango »

Maybe of some help

http://akpp-texpost.ru/AX4N.pdf

Page 4 - 2 ports available for testing both EPC and LINE PRESSURE
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