V8 Auto -> Manual conversions and computer problems. - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

NZ · 03-05-2004, 07:32

Ever since converting to manual I was always sure my car had lost low end torque. I had gutted the cats at the same time and thought that was the cause. New (and better) cats didnt solve the problem so it somewhat left me stumped... untill tonite.

I had always beleived that the EA - EB1 auto's and up to ED V8's (unsure about EF and EL but I suspect it would be the same) were able to use the original Auto version of the engine ECU when converted to manual.

This is true for the 6cyl but not the V8's.

Basically the V8 have an operating mode where in reverse gear they run a torque limiting mode to protect the reverse gear. There is a link from the auto trans ecu to the engine ecu dedicated for this mode.

The problem when changing to manual and there fore removing the auto trans ecu is that the engine ecu no longer receives the signal. This poses a problem. Here is a peice copied directly from the Ford Factory Workshop Manual: Section 7-2-70

Quote:

Default Engine Operating Modes
7B:Reverse Gear Indication
Engine Controller, EEC-IV will assume torque cut off mode in all gears. However when the calculated engine-to-road speed ratio is outside the range of the reverse gear, toque cut off is ignored. If a fault is undetected, a reduction in power may be percived in lower forward gears and shifts may be firm

So obviously the firm shifts won't apply to the manual but the lack of power will. It will be evident throughout first gear and at the start of 2nd I think. This is the exact reason why I have felt my 2nd gear was quicker than 1st to accelerate. It also explains why it doesnt show up that well on the dyno. Basically when its in 3rd gear its only at really low RPM that it will be in the torque limiting mode. There is no EEC fault code for the missing signal

The connection is between pin 3 on the 95LE trans ECU and goes to pin 5 on the engine ECU. Looking at the chart with the different states of the various outputs and inputs the Transmission Communication Link gives the EEC a 25hz or 50hz signal depending on the state (reverse or not). So that makes things harder because it isn't as simple as using a resistor and feeding pin 5 with the correct voltage.

A friend of mine who is pretty clued up with Falcon's has a couple of EB1 V8 ECU's and we are going to retrofit one into my car. We will have to wire in a BAP sensor and also rewire the WAC relay for the air conditioning. This will also mean I will lose the recirculation override feature of the air con system.

jmartion · 03-05-2004, 07:43

i'm sure thats something alot of folk dont know about!

the dudes who did my conversion said i had manual ECU.. since they did a top notch jon i beleived em. however, how can i double check??

Rmyers · 03-05-2004, 08:03

Read that three times before it sunk in properly

Should finally be able to keep up with the TQE's ey Karl

NZ · 03-05-2004, 08:05

Get the part number off it. Im going to bed now but If someone already hasn't checked it ill post the various part numbers of the ECU's.
Im so wrapped with this. Maybe now I will beable to beat my previous auto transmission 1/4 mile times

15.95 with auto and 3.27 diff
15.96 with manual and 3.45 diff. The car was sucking hot air from the engine bay but it still goes to show the diffeence.

NZ · 03-05-2004, 08:07

Quote:

Originally Posted by Rmyers

Read that three times before it sunk in properly

Should finally be able to keep up with the TQE's ey Karl

Yes steven... what ever you say

NZ · 03-05-2004, 12:36

Manual 5.0 ECU part numbers:

91DA 12A650 DX
91DA 12A650 FX

Both of these can be smartlock or non smartlock. And both can be EB1 or EB2/ED. X can be any letter but I assume the later letter would suggest perhaps what era ECU it is? Can anyone shed some light on this?

My problem is my car is EB2 but non smartlock. How many 5.0 manual cars were made in the period of 2/92 - 10/92. How many of those will be wrecked and have ECU's avalible? Hence the reason why we have to use the EB1 version (since we already have it).

!Gn|T|0n · 03-05-2004, 16:02

I'm going to make this suggestions with the comment that I've not personally researched this scenario Karl, nor do i know much about the workings of the BTR transmission controller when there's no BTR in sight, but if the trans ECU behaves in a sane (by some stretch of the word sane) way when installed but disconnected from the transmission, couldn't you use your original ECU (and hence retain the features that the EB1 V8 ECU will rob you of) and reinstall the trans ECU so that it keeps it happy?

Failing that it may be easier to fabricate a 25 / 50 Hz (which ever is the one used to signify 1st gear) oscillator and feed that into the ECU.

9psi EB · 03-05-2004, 16:34

NZ, you could use a small and quick $10 oscillator circuit to generate the 25 or 50hz frequency and see what the result is.

cogo_81 · 03-05-2004, 21:23

Hey NZ let me know how you go because I am running an auto computer in my car and also have similar symptons as you.

And also what would happen if you used a manual computer in a series 1 V8 auto.

NZ · 03-06-2004, 03:28

Quote:

Originally Posted by 9psi EB

NZ, you could use a small and quick $10 oscillator circuit to generate the 25 or 50hz frequency and see what the result is.

Its not a constant signal it varies apparently as in it seems to be a code of on and off's made up of the frequency. I don't know how else to explain it.