Graphics interface for the 14CUX

[danbourassa]

robertf03 said:

Tune resistors....

I've only dealt with NAS Land Rover ecms, and so far everyone I've encountered defaults to map 5.

I poked around a spare ecm and I believe it is a hardware lock. I think the daughterboard pictured contains the tune resistor, but I couldn't narrow it down to which one. From left to right, pin 1 and 2 are continuous with ecm pin 27, and pin 9 is continuous with ecm pin 5. Could someone with a Euro spec ECM snap a picture of the daughterboard in their ecm?

Robert, I'm pretty sure the daughterboards are the same. It's the software that is locked. Look at the value stored at 0x07C1 (0xC7C1 with PROM in board). This will be FF for you but 00 in TVR PROMs. Change this value to 00 and add an external resistor at Pin 5 on the 40-pin connector and you should be able to change maps. If your harness is like some I've seen, you may not even have a connection on pin 5. Steal the connection and wire from the heated screen sense (pin 8).

[robertf03]

danbourassa said:

Robert, I'm pretty sure the daughterboards are the same. It's the software that is locked. Look at the value stored at 0x07C1 (0xC7C1 with PROM in board). This will be FF for you but 00 in TVR PROMs. Change this value to 00 and add an external resistor at Pin 5 on the 40-pin connector and you should be able to change maps. If your harness is like some I've seen, you may not even have a connection on pin 5. Steal the connection and wire from the heated screen sense (pin 8).

You're the man! After I posted that I tried some TVR bins and came to the conclusion that it must be in the software. I check this board and you've confirmed it AND provided an address!
Map 0 No resistor
Map 1 Red wire,180 ohms,Australia,rest of world
Map 2 Green wire,470 ohms,UK and europe -non cat
Map 3 Yellow wire,910 ohms,saudi non cat
Map 5 White wire,3K9 ohms,european cat


So, what is the difference between the yellow and green strategies? And what does it take to unlock map 4?

[blitzracing]

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

[danbourassa]

I usually modify a 16K binary and stack it to 32K afterwards, so the address would be 0x07C1. If you are modifying a 32K binary, then add 0x4000 to the address. It's the upper half that is accessible in the board.

[stevesprint]

Robert, I’m sure you’ll be pleased to hear the daughter board in my spare ECU from a UK 1994 Land Rover is absolutely identical.
Cheers, Steve

[robertf03]

Thanks steve. This is great. I haven't had cats on the disco in a while, they are the lowest hanging thing under the frame and after the 4th y pipe was crushed by rocks I felt I'd done my due dilligence and ditched them. The range per tank is pretty bad (12 miles per US gallon with the AC on and running 93 octane ethanol dilluted garbage that they call gasoline) and I've had a few close calls in running out of fuel while doing a trail in the middle of nowhere. If running the green resistor increases the range at all, this is a huge gain.

Anyone have a spare tune resistor and plug and feel like shipping to the US? I know I could make do with bullet connectors, but I'd like to keep everything matching the manual if possible.

Edited by robertf03 on Thursday 19th September 00:49

[stevesprint]

Robert
I’ll sort you out a green resister if you pm me your address. I guess you have more flexibility with a non-cat tune, we certainly do with pre 1993 cars and that’s why I chose a 1992 Griffith !!

I fancy a tune selection switch on my dash, one tune for fun, one for economy and another without the smell of exhaust fumes.
Cheers, Steve

Edited by stevesprint on Friday 20th September 00:23

[robertf03]

Thanks. E-mail sent. I hope ditching the catalyst map will allow me to lean it out some, it was running so rich at altitude last month that I had to pull the fuel pump fuse and run the starter to clear it out a few times. I did have a failed TPS installed at the time, so that probably had a lot to do with it.

braggadocious vacation pic on Imogene Pass, Colorado. 13000 feet above sea level.

[eliot]

stevesprint said:

I fancy a tune selection switch on my dash, one tune for fun, one for economy and another without the smell of exhaust fumes.

Given the relative difficulty in mapping these ECU's I think you are better off spending your time developing a single map that matches the car more precisely. With a correctly tuned map, you should never need to "switch" maps. High load / Wide open throttle - richer, light load part throttle stoic(lambda). Granted if you are catless, you could run down into the 15's during cruise(open loop) - but that's about it really. Unless you are doing very high mileages you are not that likely to see much return on running 15's instead of 14's during cruise anyway.

I have a megasquirt with switchable maps via a dashboard switch, but it ONLY changes the ignition map - which has a few more degrees advance in it for the rare occasions that I fill up with 99ron - the fuel map is identical.

[danbourassa]

robertf03 said:

braggadocious vacation pic on Imogene Pass, Colorado. 13000 feet above sea level.

This is a great photo. I can imagine this on a Land Rover calender.

[stevesprint]

eliot said:

High load / Wide open throttle - richer, light load part throttle stoic (lambda).

Eliot
Thanks, that makes perfect sense. I would hope the guys at a good rolling road would be able to advise on AFR. I'm planning to taking my precat Griff to a rolling roll soon to prove the 14CUX can be remapped in real time and learn how much effect the hex numbers have on the AFR in the real world. In addition I would like to correct my AFR as my Griff on the rolling road at the Griff Growl peaked at 11.25A/F and produced 260 horses and 300ft/lb. Would 11:25A/F hurt the power and my pocket??
Cheers, Steve Sprint

[Steve_D]

stevesprint said:

.......Would 11:25A/F hurt the power and my pocket??
Cheers, Steve Sprint

Yes.

As a general rule richer than about 12.5 will not produce more power but will cost.

Steve

[eliot]

yes 11.25 is quite rich for an n/a engine and you should see an improvement by leaning out.
However, the usual problem with the std setup is that they run lean at high rpm due to running out of injector (100% duty cycle, cant inject any more fuel)
If you are going to get into this you might want to consider welding an m18 bung into your exhaust and buying a wideband setup - as the tailpipe setups can be inaccurate.

[spitfire4v8]

The injectors don't run out of flow, the std injectors are good for over 300bhp.

[eliot]

spitfire4v8 said:

The injectors don't run out of flow, the std injectors are good for over 300bhp.

I don't really want to get into a debate - as every car is different. When we mapped my friends Griff 500 on std injectors with megasquirt we were hitting almost 100% duty cycle at max RPM's and was getting mid 14 AFR's which was on the leaner side of comfortable. This was with two wideband lambdas welded into the headers with the pre-cats removed - post cats in place. So you cant even say it was a reading error as both banks were within a few % of each other, Photo:
http://www.mez.co.uk/dcam/DSCF2230.JPG
We then replaced the injectors and remapped to around 13's at 75-80% duty cycle. Either way the point is to keep any eye on those AFR's and listen out for knocking (very difficult in a griff doing 150mph down the local dual carriageway)

[stevesprint]

Dan/Colin/Mark anyone
Following on from the “Time to tweek the throttle pot” thread on the TVR Chimaera forum I’ve successfully tweaked my throttle pot to read 5% to 97% absolute and 0% - 97% corrected, as suggested on the thread.

Although I’ve adjusted the throttle to read 97% on full throttle my ecu still very rarely/momentarily hits the bottom row of the main fuel table. Is that the correct behaviour?

Also, as my car runs very rich across the whole rev range and open loop should I adjust the co on the Air Flow Meter or will that turn the AFM output down so I‘ll have even less chance of hitting the bottom row on the main fuel table? I want to set everything up as best as possible before I start remaping the main table.
Cheers Steve

[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.

[Kiwibacon]

cmb said:

The map adjustment factors are 16-bit values that immediately follow the last value in each of the five maps. (Typical values for 3.9L maps are around 0x5400.) Units built after mid-1992 have slightly different code with different offsets for the maps.

Adjustment factor offsets in older units:
Map 1: $C2BF
Map 2: $C3D1
Map 3: $C4E3
Map 4: $C5F5
Map 5: $C707

Adjustment factor offsets in newer units:
Map 1: $C2E7
Map 2: $C3F9
Map 3: $C50B
Map 4: $C61D
Map 5: $C72F

Also note that these are *memory* offsets, accessible via the serial port when the ECU is running. If you're looking at a binary image of the PROM, subtract 0xC000 to get the equivalent file offset.

--Colin

HI Colin

First of all, thank you so much for writing Rovergauge. Without it my 3.9 would be being recycled into coke cans.

I have a 1993 open-loop 3.9 with no cats or O2 sensors (NZ/AU spec hi comp) and I need to lean it out by about 1 A/F point. I have a wideband O2 sensor on a seperate gauge stuck on the end of the exhaust pipe for troubleshooting and tuning.
Is it really possible for mortals to write long term or short term fuel trims into these memory offsets to shift the whole fuelling map up or down? If so how do we acheive it?

Failing that I might have to write a replacement chip. I have a burner and have played similar games remapping diesels, but this is my first EFI petrol tune. Does anyone know a EEPROM chip that is suitable rather than the UV erasables?

[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...

[cmb]

Kiwibacon said:

HI Colin

First of all, thank you so much for writing Rovergauge. Without it my 3.9 would be being recycled into coke cans.

I have a 1993 open-loop 3.9 with no cats or O2 sensors (NZ/AU spec hi comp) and I need to lean it out by about 1 A/F point. I have a wideband O2 sensor on a seperate gauge stuck on the end of the exhaust pipe for troubleshooting and tuning.
Is it really possible for mortals to write long term or short term fuel trims into these memory offsets to shift the whole fuelling map up or down? If so how do we acheive it?

Failing that I might have to write a replacement chip. I have a burner and have played similar games remapping diesels, but this is my first EFI petrol tune. Does anyone know a EEPROM chip that is suitable rather than the UV erasables?

Mark is correct. It's not possible to change fueling by writing locations in RAM, as the fueling values are all read directly from the ROM.