Lucas 14CUX Firmware / Tune Memory Addresses (Offsets)

The fuel data and software program are stored together with a combined size of only 16KB (16,384 bytes), the data and program together are then duplicated on the tune chip to full 32KB (32,768 bytes). The 14CUX’s CPU only accesses the second copy at prom file Offsets $4000 to $7FFF, but RoverGauge’s “Save Prom Image” option only saves a single copy to a Prom file with offsets $0000 – $3FFF. As a result I’ve listed both sets of prom offset addresses in the last table. Please note all of the following prom chip offsets / addresses start at the beginning of the prom file at offset $0000 and are not to be confused with the CPU’s internal addressing of C000 - FFFF. You can use the 14CUX Toolkit to duplicate the RoverGauge single copy ready for flashing to a chip, plus the 14CUXToolkit can fix the checksum if you’ve made your own changes directly in the file.

It’s important to note the location of the fuel data on the prom moved in 1993 for revision R2666 onwards, the old and new file offsets are listed in the first two tables below. In TunerPro you’ll see there are two sets of fuel tables, "R2422" tables for the older prom layout and the other tables are for the later R2666 on layout. The RoverGauge software is clever enough to automatically identify the correct location of the fuel map to display.

Please note TunePro has now been configured to update the majority of the settings in the tables below except for the Road Speed comparator as its location varies in different tunes and also not for the RPM set points as its not very straightforward to change the RPM brackets. To run the extended 6203 RPM fuel table please switch to using one of the tunes with the extended RPM table already set-up. If you prefer to create your own RPM brackets then please see the section below on the RPM set points, if you don’t extend the RPM table correctly you could end up with a RPM curve with glitches which then cause a glitches is the ARF as demonstrated in the graphs to the right.

AFR Glitch cause by bad RPM brackets See below

Fuel Map Offsets for Revision R2422 or earlier
Contents	Limp	Map 1	Map 2	Map 3	Map 4	Map 5
Fuel Table Start	$0000	$023F	$0351	$463	$575	$0687
Multiplier (different CC)	$0080	$02BF	$03D1	$04E3	$05F5	$0707
Coolant warn up table	$00B5	$02C1	$03D3	$04E5	$05F7	$0709
ADC Mux	$0082	$0339	$044B	$055D	$066F	$0781
AFM Table Row Scalar	$01C9	$0349	$045B	$056D	$067F	$0791
RPM Safety Delta		$034A	$045C	$056E	$0680	$0792
RPM Safety Limit		$034B	$045D	$056F	$0681	$0793
Map Last Byte		$0350	$0462	$0574	$0686	$0798

Fuel Map Offsets for Revision R2666 on
Contents	Limp	Map 1	Map 2	Map 3	Map 4	Map 5
Fuel Table Start	$0000	$0267	$0379	$048B	$059D	$06AF
Multiplier (different CC)	$0080	$02E7	$03F9	$050B	$061D	$072F
Coolant warn up table	$00B5	$02E9	$03FB	$050D	$061F	$0731
ADC Mux	$0082	$0361	$0473	$0585	$0697	$07A9
AFM Table Row Scalar	$01C9	$0371	$0483	$0595	$06A7	$07B9
RPM Safely Delta		$0372	$0484	$0596	$06A8	$07BA
RPM Safely Limit		$0373	$0485	$0597	$06A9	$07BB
Map Last Byte		$0378	$048A	$059C	$06AE	$07C0

Map 1-5 data length = 274bytes/112 hex (128 FuelTable + 2 Fuel scalar + 144)

Generic Fuel Data Setting
Contents	RoverGauge 16KB	Full 32KB Chip File
Disable application of long term trim 00=Off; 80=On	$00A0	$40A0
Overrun fuel cut minimum start $10 (1600rpm), $09 (2,700rpm) $08 (3,000), $07 (3,400), $06 (4,000rpm), $05 (4,800rpm)	$0137	$4137
Neutral gear idle increase	$0159 - $015A	$4159 - $415A
A/C idle increase	$015B - $015C	$415B - $415C
Base idle	$0176 - $0177	$4176 - $4177
AFM Row centre offset	$01C7 - $01C8	$41C7 - $41C8
Heated screen idle increase	$01E9 - $01EA	$41E9 - $41EA
HiRPMAdcMux	$0231 - $023E	$4231 - $423E
Disable Tune resister (north USA) Locked = FF, unlocked 00	$07C1	$47C1
MIL On = FF, Off = 00	$07C2	$47C2
Start of the program code	$0800	$4800
RPM Set Points Table	$0800 - $083F	$4800 - $483F
Road Speed Comparator for different sensors (Offset varies)	$1409 (R3652)	$1323 (R2967)
Engine Tuner/Builder ID if not FF	$3D0E	$7D0E
Revision ID	$3FE9 - $3FEA	$7FE9 - $7FEA
Checksum fixer (See note below)	$3FEB	$7FEB
Tune ID	$3FEC - $3FED	$7FEC - $7FED
Processor's reset vector	$3FFE - $3FFF	$7FFE - $7FFF

AFM Row Table Scalar & AFM Row centre offset

When using a larger AFM you can improve the bottom row usage and move the idle row by adjusting the AFM Table Row Scalar & AFM Row centre offset (in TunerPro see TABLE 1-5 MAF Scalar & TABLE 1-5 MAF Scalar Offset). The scalar increases/decrease the scale of the rows and the offset move the mid point of the rows up and down.

RPM Set Points Table

RPM set points should be extended to 6250 RPM for TVRs or to the red line of your engine so that you have mixture control past 5500 RPM.

The rpm set points are arranged in 4 columns starting at prom offset $800 with the highest RPM first. The first 2 columns of the table are the 16-bit RPM set points represented as the spark period (2 uSec units) and the 3^rd and 4^th columns are used to keep the AFR smooth between the set points.

Smooth 6250 RPM Table

04 B0 40 00 - 6250 RPM Delta

05 94 00 12 - 5250 RPM 1000

06 A8 80 F0 - 4400 RPM 850

07 9C 00 10 - 3850 RPM 550

08 9A 80 F6 - 3405 RPM 445

0A 76 80 7F - 2800 RPM 605

0D F3 80 48 - 2100 RPM 700

10 BD 80 60 - 1750 RPM 350

14 ED 80 3D - 1400 RPM 350

1A A2 80 2C - 1100 RPM 300

20 8D 80 2B - 900 RPM 200

25 8F 80 33 - 780 RPM 120

29 DA 80 3B - 700 RPM 80

2F 40 80 2F - 620 RPM 80

3D 09 80 12 - 480 RPM 140

92 7C 40 2F - 200 RPM 280

If you want to create your own RPM set points do not simply raise the top bracket but spread the difference out over several brackets and the 3^rd and 4^th columns will probably require changing along with the 16-bit period value. For further information please see the readme file for the RPM Table Simulation tool that can be used to test different RPM set points.

RPM Table with Glitch that caused ARF Glitch above

Smooth RPM Table to 6250

Checksum Fixer

Every time the ignition is first turned on the ECU program reads though the entire prom chip calculating the checksum to determine if the map is corrupt or been hacked. If the checksum isn’t correct the checksum error code is set which is merely an indication that the prom file has been altered and is not the code of death unless your prom is badly corrupt. Therefore after updating the prom file with TunerPro the equation below is used to calculate a new checksum fixer to a void the checksum error. The checksum can also be fixed with the 14CUX Toolkit described on the gadgets page.

New Checksum Fixer = Old Checksum Fixer - Sum of all bytes in bin file + 1

CO Trim screw adjustment

For non-cat vehicles it very important for smooth running the CO trim voltage is set correct for the different tunes. The CO trim adjustment is via 7/32 Allen key on the side of the AFM and basically the ECU supplies 5v and the variable resister in the AFM pulls the voltage down to ground. Please note RoverGauge only show the live CO trim adjustment once the engine is running or stalled by turning the ignition turning off long enough to allow the engine stop and then quickly back on again.

TEMPERATURE FUEL MULTIPLIER matrix

The column headings for the MAP TEMPERATURE FUEL MULTIPLIER matrix (0x00, 0x36, 0x56, 0x145, 0x171, 0x194, 0x224, 0x238)

on the left refers to hot temp and on the right refer to cold temp.

Coolant Temperature based Idle Control Simulator Program

www.stevesprint.com/remap-14cux/Coolant_Idle_Ctrl_Simulator.zip

Land Rover 3.9

Steve Lower Cold Idle

Disable Long Term Trim

If you want to re-map a cat map with without lambda control Mark Blitzracing has proved you can copy map 5 with multiplier to map2 then work on map 2 with the CO trim set to the mid point of 1.25 volts which equals lambda trim 0%. When finished simply copy the remapped map 2 back to map 5.

In addition Lucas actually provided a means of turning off long term trim by changing the “Disable application of long term trim” byte. The value at prom offset $00A0 is normally $80 but changing this to $00 (clearing bit 7) the application of the long term trim is bypassed. The long trim is still calculated and displayed by RoverGauge but is simply not be added to the fuel value. Interesting as the trim is calculated as normal and not applied the ECU keeps adding more and more trim until it hits 100%. Please note when setting $00A0 to 00 we are current not sure if the short trim is still calculated and applied.

ADCMux & HiRPMAdcMux to remove Road Speed Limiter

AdcMux stands for Analogue to Digital Multiplexer and is a list of sensors that the program uses to control the order the input sensors are read. Each map has its own AdcMux plus their is an additional power up AdcMux list that explains why the CO trim is not read until the engine fires up. While the rpm are above 4185 and the throttle is more than 70% the software uses the special HiRPMAdcMux table in place of the current maps AdcMux table that is heavily loaded with road speed measurements, the 87s. Lucas had a lot of trouble with the road speed limit and the High RPM MuxTable was possibly another patch to try to make the thing work correctly. The actual road speed limiter is in the program code and not the data section. TVR remove the road speed sensor from this list for precats to disable the road speed limiters but on later cars TVR reverted back to the Land Rover HiRPM AdcMux containing the limiter and bypassed the limiter in the program code that works at all RPM. The actually road speed limit is set in the code and it’s location varies between revisions, try look at the value at $2A41 and if it's $C4 then that is the limit in KPH (196 KPH or 122 MPH).

Input Sensor Numbers

87 - Road speed transducer

86 - Air con load input

02 - Air flow sensor (main signal)

03 - Throttle pot

84 - Coolant temp sensor

8D - O2 Reference Voltage

88 - Main relay voltage

8B - Fuel temp sensor

80 - Inertia switch

85 - Auto neutral switch

81 - Heated screen sense

09 - CO Trim screw

8E - Diagnostic plug

Map	AdcMux List
2 (non cat)	$87,$86,$02,$03,$84,$02,$8D,$88,$02,$8B,$80,$85,$81,$09,$8E,$FA
5 (cat)	$87,$86,$02,$03,$84,$02,$8D,$88,$02,$8B,$80,$85,$81,$8E,$FA,$FA

Year	Firmware	Limiter	Hi RPM Adc Mux
TVR 1992	R2422	Removed	8B 86 02 03 84 02 8D 88 02 8B 80 85 81 FA
LR 1991	R2422	Limited	87 02 87 86 87 02 87 87 87 87 87 87 87 F7
LR 1994	R3833	Limited	87 02 87 86 87 02 87 87 87 87 87 87 87 F7
TVR 1993on	R2967	Limited	87 02 87 86 87 02 87 87 87 87 87 87 87 F7

Tunes resistors

Wire Colour	Ohms	Catalyst	Application
Red	180	No	Australian 3.5 & 3.9
Green	470	No	Europe & UK 3.9 (or 3.5 Disco)
Yellow	910	No	Europe & UK 4.2 and Gulf States 3.9
Blue	1800	Yes	Europe & UK 4.2 and Gulf States 3.9
White	3900	Yes	Europe & UK 3.9 (or 3.5 Disco)