Instructions to change fuel maps on 14CUX Griffith, Chimaera

[blitzracing]

spitfire4v8 said:

The only thing I can't work out at the moment is the rapidly richening mixture right at the end of the rpm scale .. no amount of playing with scalars and fuel map would alter the basic trend there. An extra mapping point for 6500rpm would be fabulous!

Ive got a feeling the extra fuel is added from the throttle pot input but I dont know how. Heres MA bit on his chip.

"Where appropriate the map is extended to 6000-6500 RPM as determined by the application"

[Podie]

Looks like good progress.

What can be done to stop the pinking?

[stevesprint]

Jools, Congratulations you've remapped the 14CUX.

I'm very impressed you've put into practise everything our America friends have taught us and successfully re-scaled the larger AFM. I personally thought the standard AFM wasn't restrictive below 250 bhp so I would guess the improved fuelling is also contributing to the increased power and torque, but I'm no expert.

It's also excellent news you have proved mapping a CAT car is simpler than we all first thought and you can actually map the engine up to 3,400rpm from the engines own lambda sensors. Plus it's brilliant the RoverGauge lambda trim shows you the actual percentage correction required and you can enter that percent into TunerPro to make the correct adjustment.

Podie said:

Looks like good progress.
What can be done to stop the pinking?

Podie - Sounds like its time Jools start offering his customers a mappable ignition module like this one below for £100. I don't think they would be too complicated to fit, except you do have to lock the mechanical advance.
http://www.ebay.co.uk/itm/Electronic-ignition-Mapp...
Interesting, a mappable ignition module for £100, I'll put one on my Santa list.

Edited by stevesprint on Monday 11th November 09:00

[Podie]

stevesprint said:

Podie - Sounds like its time Jools start offering his customers a mappable ignition module like this one below for £100. I don't think they would be too complicated to fit, except you do have to lock the mechanical advance.
http://www.ebay.co.uk/itm/Electronic-ignition-Mapp...
Interesting, a mappable ignition module for £100, I'll put one on my Santa list.

Sounds like Joolz has his next project

[blitzracing]

stevesprint said:

http://www.ebay.co.uk/itm/Electronic-ignition-Mapp...
Interesting, a mappable ignition module for £100, I'll put one on my Santa list.

Dont touch that unit, its only 2d mapping and completely unsuitable for a road car, as it has no vacuum take off for light load ignition timing, so it hits the fuel economy badly- very much a backward step from even the mechanical system you currently have. The Aldon Amethysist is the one you need for £200. From what I read on its spec' sheet it should interface with the Lucas ignition amp without problem.

http://www.aldonamethyst.co.uk/

[stevesprint]

blitzracing said:

Dont touch that unit, its only 2d mapping and completely unsuitable for a road car, as it has no vacuum take off for light load ignition timing, so it hits the fuel economy badly- very much a backward step from even the mechanical system you currently have. The Aldon Amethysist is the one you need for £200. From what I read on its spec' sheet it should interface with the Lucas ignition amp without problem.

http://www.aldonamethyst.co.uk/

Agreed, sounds much better as it takes its input from a standard 12v distributor output including ours. Plus it can switch between two stored maps so you can switch between unleaded and super unleaded without a laptop. Would you go for the Vacuum or throttle pot version????

Edited by stevesprint on Saturday 9th November 22:11

[blitzracing]

stevesprint said:

Jools, Congratulations.
I'm very impressed you've put into practise everything our America friends have taught us and successfully re-scaled the larger AFM. I personally thought the standard AFM wasn't restrictive below 250 bhp so I would guess the improved fuelling is also contributing to the increased power and torque, but I'm no expert.

I was a bit surprised at the 150 BHP figure as well, as here are two back to back curves on a tuned 4.5, one with the lucas 5am, and one with the dare I say it Torqueflow AFM. You can clearly see the split point at around 240 BHP.

[blitzracing]

stevesprint said:

Agreed, sounds much better as it takes its input from a standard 12v distributor output including ours. Plus it can switch between two stored maps so you can switch between unleaded and super unleaded without a laptop. Would you go for the Vacuum or throttle pot version????

Edited by stevesprint on Saturday 9th November 22:11

Vaccum, as its a real value for the engines airflow (or lack of it in this case).

[stevesprint]

blitzracing said:

spitfire4v8 said:

The only thing I can't work out at the moment is the rapidly richening mixture right at the end of the rpm scale .. no amount of playing with scalars and fuel map would alter the basic trend there. An extra mapping point for 6500rpm would be fabulous!

Ive got a feeling the extra fuel is added from the throttle pot input but I dont know how. Heres MA bit on his chip.

"Where appropriate the map is extended to 6000-6500 RPM as determined by the application"

Mark
That's an interesting thought. You can see from Dan's notes below their are three throttle opening rows in the throttle table and that you only have to alter the second column on each row for a warm engine. I guess throttle table changes would affect the throttle response across the whole rev range.

danbourassa said:

The top row is always the coolant sensor count value and this tells the software what column of data to use. Only one column is in play at any given engine temperature. For example, if the coolant temp count reads 0x23 (approx 190 deg F),
only the second column would be in play (the next column to the right of this value).
So, using the example below, if you want to tune a fully warmed engine, you are now down to just 5 values to be concerned about.

; this 6 x 10 table is used to calc the throttle pot direction & rate (the 1st derivative)
; the resultant value is offset by adding 1024, stored at 0x005D/5E and ultimately used
; to dynamically adjust the fueling

New New
Map2 Map5
3FB 731 : 18 31 5A 73 89 99 B3 CC DD EA ; <-- coolant temp reading (low is hot, high is cold)
405 73B : 05 06 08 0A 10 1C 23 28 30 30 ; <-- throttle opening (compare value or limit)
40F 745 : 04 06 07 08 08 00 00 00 00 00 ; <-- throttle closing (compare value or limit)
419 74F : 2D 32 3C 50 64 FF FF FF FF FF ; <-- throttle opening (multiplier)
423 759 : 1C 18 10 0C 0B 14 14 19 19 19 ; <-- throttle opening (multiplier)
42D 763 : 24 18 10 0C 0B 1E 1E 1E 1E 1E ; <-- throttle closing (multiplier)

[danbourassa]

It may be possible to extend the fuel map yourself. If you look at the very beginning of the code section, which is at 0x0800 (PROM address) or 0xC800 (board address). you will see this data:



Here are those first 64 bytes shown in table format:

C800 : 05 53 40 00      ; 5502 RPM
C804 : 06 2A 00 13      ; 4753 RPM
C808 : 07 25 00 10      ; 4100 RPM
C80C : 07 D0 00 18      ; 3750 RPM
C810 : 09 73 80 9C      ; 3100 RPM
C814 : 0A D9 80 B7      ; 2700 RPM
C818 : 0E A6 80 43      ; 2000 RPM
C81C : 10 BD 80 7A      ; 1750 RPM
C820 : 14 ED 80 3D      ; 1400 RPM
C824 : 1A A2 80 2C      ; 1100 RPM
C828 : 20 8D 80 2B      ;  900 RPM
C82C : 25 8F 80 33      ;  780 RPM
C830 : 29 DA 80 3B      ;  700 RPM
C834 : 2F 40 80 2F      ;  620 RPM
C838 : 3D 09 80 12      ;  480 RPM
C83C : 92 7C 40 2F      ;  200 RPM 

This is what sets up the fuel map RPM brackets. The first 2 columns of the table are 16-bit values representing spark period (2 uSec units). Software traverses the table from top to bottom subtracting the newly measured spark period until it finds the correct bracket. The 3rd column tells the software how to handle the remainder for interpolation purposes (not to be confused with the later 2-dimensional fuel map interpolation). And the 4th column is a number to be multiplied with the remainder. The left nibble of the fuel map column index is formed by the bracket number and the right nibble is formed by how the remainder is treated.

Value $80 means use the upper byte of the remainder (because it could be greater than 8-bits) and value $00 means use the lower byte. Near the top of the chart the brackets get numerically closer so the delta or remainder can't be greater than 8-bits. Value $40 is the end-case condition.

This table can (and should) be extended to 6200 RPM for TVR (or whatever the red-line is for your engine) so that you have mixture control past 5500 RPM. I would not simply raise the top bracket but spread the difference out over several brackets. This is a piecewise linear approximation of a curve, so a large spread between points can cause greater error. Remember that the 3rd and 4th column data will probably need changing along with the 16-bit period value.

I intend to model the code in C when I get a chance and should have more info soon.

Edited by danbourassa on Sunday 10th November 18:57

Edited by danbourassa on Sunday 10th November 20:37

[Chuffmeister]

spitfire4v8 said:

That's a huge difference in output!

[stevesprint]

danbourassa said:

It may be possible to extend the fuel map yourself. If you look at the very beginning of the code section,..........

DAN, YOUR AN ABSOLUTE GEM!!!!

[stevesprint]

karlspena said:

Maybe there is a way to synchronize the TimeStampLogger with RoverGauge so the stamps match. I think PLX's software does logging as well, but I bet it would not be as easy to sync. Don't feel bad if I get a DM-6, I've been thinking to do it for a while. It's really neat since you can have several different sensors display on just one gauge. And it's really thin! Fits anywhere. Yes, by combo I mean dm-6 + sm-afr. It costs about 190 dls shipped. Quite a deal for a gauge that allows virtually infinite expansion options AND PC output for logging

Mark & Karls
I’ve successfully modified my Time Stamp Logger program to work with both the AEM AFR Gauge and the Plx SM-AFR sensor. There is no installation so just unzip and run with the following command line options:
timelogger loggertype comport
The first example below is for Mark
timelogger timelog 8
timelogger plx-afr 1
The com port at the end is optional but when used it will automatically connect and start receiving data as I’ve pre-configured the serial setting for the different loggers.

I’ve tested it the best I can with a serial loop back plug and included my test input and output files for both sensors.

Please do hesitate to email me with any issues & Good Luck, Steve
http://www.stevesprint.com/remap-14cux/TimeLogger....

karlspena said:

Is there a way to combine the output of this with RoverGauge's to have a precise measurement of AFR on each cell of the map? (I know there are other factors in play, but this would be awesome).

Karls – Yes, I’ll try modifying my time logger, as discussed, before the spring to match & merge the RoverGauge log with the timed AFR log, ready to import into an excel 8x16 pivot table. I’m sure we could create an excel macro to automate the excel import.

I really must now work on my Griff's winter projects but at least I've proved I can time stamp log the AEM AFR Gauge and Plx SM-AFR ready for merging.

Edited by stevesprint on Wednesday 1st January 22:01

[danbourassa]

For those interested in extending the RPM table (why do I get the feeling Steve is one of them?), I posted the source code for a simple program that models the 14CUX. This allows scanning through the entire RPM range and creating an output file. The file is easily graphed with Excel (or similar) and validates your changes. The ideal curve must be (as math geeks would call it) a monotonic function which simply means a curve that changes smoothly and in one direction. If there is an abrupt step or discontinuity, you can see it and correct it. There is also a Word doc with graph images. I've found that google doesn't render the images online as well as when you download the file.

https://drive.google.com/?tab=wo&authuser=0#fo...

[blitzracing]

So..... I take it the scan of the aftermarket chip shows that even though the RPM bands have been lifted, so no effort has been made to make the transitions smooth as the fueling levels drop away again as the RPM rises?

[danbourassa]

blitzracing said:

So..... I take it the scan of the aftermarket chip shows that even though the RPM bands have been lifted, so no effort has been made to make the transitions smooth as the fueling levels drop away again as the RPM rises?

Those were my thoughts, as well. Although it may not have been a question of effort as much as understanding. When I saw this, I went back at looked at the table. The 3rd and 4th columns are unchanged from the original LR code.

[stevesprint]

When I saw Dan’s first post regarding extending the rpm range I soon worked out the following formula to convert from rpm to hex for columns 1 & 2.

5502 rpm divided 60 seconds equals 91.7 revs per second
Then dividing 1 sec by 91.7 rps equals 0.010905sec (the time for 1 rev in sec)
and divide by 8 for time between sparks in second. 0.001363
Convert 1363 (now usec) into hex at any site like
http://www.statman.info/conversions/hexadecimal.ht...

I then decided on 6000, 5250, 4500rpm for my top three rows and used the formula above to calculate the hex for columns 1 and 2 as below.

C800 : 04 E2 40 00 ; 6000 RPM
C804 : 05 94 00 13 ; 5250 RPM
C808 : 06 82 00 10 ; 4500 RPM

I've now noticed from Dan’s second post my 3 rpm rows are the same as the aftermarket chip and Dan’s graphs show how important it is getting the 3rd and 4th column correct. Therefore, Dan a big thanks for putting so much effort into demonstration the important of columns 3 & 4.

[danbourassa]

stevesprint said:

When I saw Dan’s first post regarding extending the rpm range I soon worked out the following formula to convert from rpm to hex for columns 1 & 2.

Steve, you keep forgetting the magic number. Just divide 7,500,000 by RPM and then convert to hex.

[danbourassa]

stevesprint said:

Convert 1363 (now usec) into hex at any site like
http://www.statman.info/conversions/hexadecimal.ht...

Also, I'm sure your desktop calculator has a hex mode. If you're using Windows, just set the view to Scientific.

[stevesprint]

danbourassa said:

Steve, you keep forgetting the magic number. Just divide 7,500,000 by RPM and then convert to hex.

LOL!!!! - Thanks for making me smile after a busy day at work. Must be the only straight forward thing with the 14CUX.