Graphics interface for the 14CUX

[blitzracing]

If you can reverse the image on the Nexus, and lay it on the dash then you'd have a head up display! I take it the Pi run linux in some flavor? Not had a play with RoverGuage other than windows so far.

[blitzracing]

Ive only got one non modified Lucas map, but I dont have clue what engine set up it was. Its Marked 3604 if its any use Ill copy it?

[blitzracing]

Heres the only tune listing I have:

Model Tune # Description
Range Rover Classic 3.9 Low
CR

R2103 Initial production tune
Range Rover Classic 3.9 Low
CR
R2161 Desensitized OBD, IAC refinements
Range Rover Classic 3.9 Low
CR
R2306 Fixed A/C glitch @ 65 mph (2250rpm); eliminated tune resistor
(Code 21)
Range Rover Classic 3.9 Low
CR
R2419 Desensitized OBD, , prinarily Code 48; Service Actioon (Recall
CA)
Range Rover Classic 3.9 Low
CR
R2665 Improved IAC control, new strategy for IAC OBD; further OBD
desensitization
Range Rover Classic 3.9 High
CR
R2813 Initial production tune
Range Rover Classic 4.2 High
CR
R2926
B
Initial production tune
Defender 3.9 High CR R3038 Initial production tune
Range Rover Classic 3.9 High
CR
R3100 Low Reed Vapor Pressure fuel tune
Range Rover Classic 4.2 High
CR
R3102 Low Reed Vapor Pressure fuel tune
Range Rover Classic 3.9 High
CR
R3315 MIL on no code fix (interim)
Range Rover Classic 4.2 Low
CR
R3316 MIL on no code fix (interim)
Range Rover Classic 3.9 Low
CR
R3326 Low Reed Vapor Pressure fuel tune (interim)
Range Rover Classic 3.9 Low
CR
R3339 MIL on no code fix (interim)
Defender 3.9 High CR R3340 MIL on no code fix (interim)
Defender 3.9 High CR R3341 Low Reed Vapor Pressure fuel tune (interim)
Range Rover Classic 3.9 High
CR
R3342
A
MIL on no code fix (interim)
Range Rover Classic 4.2 High
CR
R3343
A
MIL on no code fix (interim)
Range Rover Classic/ Discovery
3.9 High CR
R3360 Desensitized OBD 95 MY Tune (‘94 Discovery)
Range Rover Classic 4.2 R3361 Desensitized OBD 95 MY Tune
Range Rover Classic 3.9 Low
CR
R3362 Desensitized OBD 95 MY Tune; improvements for Low CR
13/14CU AND 14CUX SYSTEMS
106
Defender 3.9 High CR R3365 Desensitized OBD 95 MY Tune
Range Rover Classic 4.2 R3507 Part # PRM3361A; Interim improved Cold Start, fueling below -
22âC (- 10âF)
Range Rover Classic/Discovery
3.9 High CR
R3526 Part # PRM3360A; Note: LR Part numbers are different from
Tune numbers
Defender 3.9 High CR R3529 Part # PRM3365A
Range Rover Classic/Discovery
3.9 High CR
R3652 Operation Pride Tune
Current tune with final improved Cold Start fueling below -22âC
(-10âF).
Range Rover Classic 4.2 High
CR
R3653 Operation Pride Tune
Current tune with final improved Cold Start fueling below -22âC
(-10âF).
Defender 3.9 High CR R3654 Operation Pride Tune
Current tune with final improved Cold Start fueling below

[blitzracing]

Taking several steps backwards (possibly anyway). As RoverGauge shows you the current load point in the map at any given point, is it as straight forward as knowing the location and simply increasing or decreasing the hex value in that location to add or remove fuel? I think Im missing something on how the map works as Id expect the values to go up with engine load and RPM but this does not seem to be the case? Also if remapping a catalysts car you will need to turn off the lambda feedback to stop the wide correction range- it may be as simple as unplugging the probes so it runs without correction, but it does throw a fault code in the process- although Im not sure if it drops back to map 0 for this particular fault. Much easier Id think on the non cat map.

[blitzracing]

danbourassa said:

blitzracing said:

Taking several steps backwards (possibly anyway). As RoverGauge shows you the current load point in the map at any given point, is it as straight forward as knowing the location and simply increasing or decreasing the hex value in that location to add or remove fuel? I think Im missing something on how the map works as Id expect the values to go up with engine load and RPM but this does not seem to be the case? Also if remapping a catalysts car you will need to turn off the lambda feedback to stop the wide correction range- it may be as simple as unplugging the probes so it runs without correction, but it does throw a fault code in the process- although Im not sure if it drops back to map 0 for this particular fault. Much easier Id think on the non cat map.

Mark, keep in mind that the injector bank fires for every 4 coil sparks. As RPM increases, fuel increases linearly. In a perfect world there would be no change in value across the row and the fuel map could be reduced down to 1 column. I think the small changes account for the inability of the injectors to close instantaneously. They are fighting fuel pressure and the inertia of internal parts. Shortening the pulses at high RPM simply keeps the fueling stable over the RPM range. The big changes, as you would expect, are the load based row to row changes.

I think you are correct about the closed loop problem. The trim will fight any changes you try to make until it hits the rail. By then, things are completely out of whack, and nothing has been learned. This should be done in open loop mode only.

So what you are saying is the base fueling is already pre calculated any given rpm / load on a linear basis, and the values in the map are effectively a "trim value" over that linear preset to cope with the mechanical variances? If this is the case it really could be as simple as altering the trim values as you can now see where the load points are at any time.


---Ill try and get the RR map copied today.

[blitzracing]

Is this any use in place of the non programmable chip with the relevant write sigal added?

http://uk.farnell.com/atmel/at28c256-15pu/ic-eepro...

Edited by blitzracing on Monday 2nd September 19:24

[blitzracing]

Id think that a good compromise then without a box of blank Eproms to hand, given a suitable programmer.

[blitzracing]

Saudi export engines run a lower compression ration, so the non cat map is changed to compensate.

[blitzracing]

The CO trim resistor only affects the mixture up to around 2400 rpm. Its a separate input to the ECU from the AFM, and does not affect the AFM output at all. That would have been too easy way of frigging the fueling! If you wanted to drop the AFM input using the Lucas 20 AM would be a good option as its voltage is consistently about 10% lower than the 5AM and it flows more air.

[blitzracing]

I dont think it can be done, as the probes are set to switch at a specific air fuel ratio, whatever you do with the software, you cant change the switch point. You need to run open loop. Its all here:

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[blitzracing]

Steve_D said:

A question for the experts please.

14CUX in a TVR.
When first started car holds a high idle which slowly reduces.
When warmed it hold the 900 idle that RoverGauge says it should.
All correct so far.
After a while with the engine well up to temperature RoverGauge shows the speed as 36mph even though the car is stationary. Sometimes the speed displayed jumps about. If the car is driven the speed remains steady and the speedo works correctly.

On the face of it I have to assume the speed module has gone wrong. I plan to send it off for testing/repair.

Now the bit I don't understand.

If the car is driven the stepper motor pregresively opens until it is full open with the tickover at about 2200rpm.
If the speed unit has failed and giving a reading of 36mph why does the ECU not just maintain a fast tickover of about 1100 as it is supposed to?

Confused.

Steve

The speedo calibration unit is not well designed- the input circuitry is prone to noise- the problem is there is a comparator chip that senses when there is a pulse from the diff sensor, using the signal as one input against a ground reference. The problem is with no signal from the diff, both inputs can sit near 0 volts, and it only takes a small amount of electrical noise on the earth input to produce a false trigger signal. This can be as simple as bad solder joints on the PCB to make the earth on the PCB float up a volt or two.

Tick over wise, you need both the throttle pot to be at its correct shut throttle voltage, and no speed signal to bring it into idle mode. RoverGauge has a nice green light on it for when this state is reached, and it should then idle at around 800 rpm (dependent on chipping). Off the top of my head I dont know what the car moving idle should be, but I know MA chips lifts it a bit to reduce rear wheel lock up between gears, but 2.2k sounds a bit high.

[blitzracing]

This is from Mike Hayes who originally worked out the issue.

A link to the data sheet for the device used in the ECU speed converter :

http://www.ti.com/lit/ds/symlink/lm2907-n.pdf

The attachment is one of the pages from the spec and from memory the circuit which shows a magnetic speed sensor is exactly the front end of the circuit in the box under the dash.

The circuit needs in built tolerance to supply and sensor noise when used on a vehicle with lots of ignition and earth noise. The following may help understanding.

Basics - The sensor is pulsing into a comparator. A comparator as it suggests is comparing the voltage level of one input to another, and when the voltage on the sensor input is higher than the reference input the output of the comparator will be low. Conversely when the voltage on the sensor input is lower than the reference input the output of the comparator will be high.

The flaw in this circuit is that when the sensor is in an idle state the input is zero volts and as it happens the reference is at zero volts, so the comparator is in no mans land where it's unstable. I'm guessing that there is a small bias at the reference in this particular device that makes this device a few tens of millivolts high, in order to work at all. However it only takes a few millivolts of supply or sensor noise to start triggering the comparator.

This is what I did to resolve it.

I cut the earth connection to pin 8. I then soldered a two resistors to pin 8 one to earth and one to Vcc (pin 6) or any other convenient supply line. Not sure what values I used but if I was doing it now I would go for 100 ohms to earth and 1Kohms to Vcc. The aim is to raise the voltage at pin 8 to about 1.5V. If you have room to add a 0.1uF capacitor across the 100ohm resistor ie Pin 8 to earth that will also help.

The wires on the SPEEDO are Green = +12V, Green/Yellow = Signal from speed sensor, Black = 0V (Grd) - may be helpful to identifying the wires on the converter

My bit:

I have a simpler mod, just involving an additional diode to the earth line- so if you can send me your "faulty" one, Ill send you this one Ive modified as a swap so you can see if it works- I dont have a car to test it on.

[blitzracing]

My Theory is to remove the black earth wire from the PCB, and solder a small signal diode between the PCB earth and the black wire, in the direction of current flow (ie + to the black wire). The idea is to put the forward voltage drop of the diode onto the earth plane of the PCB, so it sits at about .7 of a volt above the chassis ground. This means that any stray trigger voltages will have to be .7 of a volt or more before they have an affect. Its just an idea as I cant test or measure the voltages in its original situation.

[blitzracing]

Any diode will do- you just want the .7 voltage drop

http://www.ebay.co.uk/itm/1N4007-General-Purpose-D...

[blitzracing]

Thats fine.