Instructions to change fuel maps on 14CUX Griffith, Chimaera

Instructions to change fuel maps on 14CUX Griffith, Chimaera

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Discussion

davep

1,044 posts

242 months

Sunday 19th July
quotequote all
stevesprint said:
Dave

To be clear we know the "injector firing/inlet valve open for half a squirt" twice per crank revolution therefore one per cam revolution.

Also don't forget the mechanical advance (upto +18°) and vacuum advance (upto +10°) will also alter the injector firing time up to 28°, I always assumed that's why the code smooths the rpm.

Are the pressure pulses the vacuum in the inlet?
In the example, your hoped for injector firing when inlet valve open event happens to occur for cylinders 1 (odd bank) and 4 (even bank), so within a single revolution of the crank. Obviously the phasing of the injector firing pattern will shift in accordance with the ignition timing curve, but the injector firing pattern will remain the same and in symmetry.

Pulses travel up and down the tuned manifold tracts as a result of pressure differences between atmosphere and the variable vacuum at the inlet cylinder port, so mixing the air and fuel charge or load within the tract; the frequency and amplitude of these pulse waveforms are determined by many factors including rpm, harmonics, tract length, diameter and shape. Factors that would have probably been taken into consideration during the original coding of 14CUX and its use with disc injectors.

indigochim

962 posts

88 months

Monday 20th July
quotequote all
stevesprint said:
Please let me know if you experience any issues with that combine tune especially with idle as we’ve learnt a lot since then and its probably time to update that tune.
Great thanks I've written one of those and will give it a go.

davep

1,044 posts

242 months

Tuesday 21st July
quotequote all
stevesprint said:
... while bimbling along as I do, unlike you at Millbrook thumbup
Five years ago ...

Donkercam

22 posts

92 months

Tuesday 21st July
quotequote all
Hi Steve,

Is your "TVR 430 Precat and 450 CAT based on LR R3652 with Extended Fuel Table to 6250RPM" program run on chimaera CAT 500 ?

Thanks

Cam

stevesprint

Original Poster:

1,059 posts

137 months

Sunday 26th July
quotequote all
Donkercam said:
Hi Steve,

Is your "TVR 430 Precat and 450 CAT based on LR R3652 with Extended Fuel Table to 6250RPM" program run on chimaera CAT 500 ?

Thanks

Cam
Cam
No sorry not to my knowledge, however I could build a 500 version but you'd have to get it checked on a rolling road.


Here's the factory 1994 Griff 500 map and below is the factory Chimmy 450 fuel table stretched to 6250 rpm which surprisingly have a higher fuel multiplier from the factory, meaning richer.



stevesprint

Original Poster:

1,059 posts

137 months

Sunday 26th July
quotequote all
davep said:
Five years ago ...
Dave
Thanks for the picture and blast around the Alpine test track & down the mile straight, you were so fast and smooth no one would know you drive with a hand control. I was also very impressed with your clever clutch switch on your gear lever, its like a manually controlled BMW SMG gearbox.

You can tell it was a fab day by the size of the smile on your face.


Lets hope Millbrook is repeated again next year as it was cancelled this year.
Stay Safe, Steve Sprint

indigochim

962 posts

88 months

Friday 28th August
quotequote all
indigochim said:
stevesprint said:
Please let me know if you experience any issues with that combine tune especially with idle as we’ve learnt a lot since then and its probably time to update that tune.
Great thanks I've written one of those and will give it a go.
Finally put this in the car. I was hoping to fit a zif socket while I did the swap but as it happens there's no space for one. I hung of on fitting as I didn't fancy a major change before taking the car to Europe but now I'm back have bitten the bullit. I'm in quarantine till tomorrow so didn't take it for a run but will be out in it on Sunday for a trial. I'm also planning on fitting the 4 port Bosch fuel injectors soo too. Maybe after that I'll have to take a trip to Chesterfield for a remap or a swap to an aftermarket kit.

As it is on the drive it ticks over and revs nicely.

TRIUMPHBULLET

374 posts

71 months

Saturday 29th August
quotequote all
Hi all, I had a play in the car last weekend and found that the engine would cut out at almost 4000 rev/min, it is really smooth up to this point. The boost level shown at the time was 5lb/in2. Normally aspirated the car only reached the last but one bottom row even at 5000 + rev/min. the engine is a std 3.9, std cam and I have put Steve Sprints TVR 4.3 precat map in for now.
Had a look at the log and fuel map seems to hit the bottom row just before this. My passenger confirmed this as they were looking at the Rovergauge display.
If I want to extend the afm range of the map do I increase the Row scalar value (91 at moment) or decrease it to compensate. Also, will altering the Maf scalar offset value up (30 at moment), move the idle highlight up the table or down? I suspect even a modest alteration will affect the table so wish to tread carefully.
I know the fueling will need altering but that seems pointless till the afm scaling is correct.
Regards, Paul.


blitzracing

6,086 posts

178 months

Sunday 30th August
quotequote all
You might find you are out flowing the AFM if you are running a turbo as it only goes to 5 volts, at which point you would be on the bottom row of the map, whatever engine size you have. The fix is to fit the larger Lucas 20 AM or Bosch equivalent and then do your re scaling, but worth checking the output with a test meter under load. The resolution becomes very poor at near peak airflow on the 5AM as the response curve flattens off badly as it gets towards 5v, and a bigger AFM will improve this.

TRIUMPHBULLET

374 posts

71 months

Sunday 30th August
quotequote all
Thank you for the reply, I have a supercharger and suspect you are right although at 5 lb/in2 boost I did not think a std 3.9 would be capable of causing that problem.
I have a 20AM in my possession so will have a look at fitting that and see how it goes.

stevesprint

Original Poster:

1,059 posts

137 months

Thursday 3rd September
quotequote all
indigochim said:
Finally put this in the car. I was hoping to fit a zif socket while I did the swap but as it happens there's no space for one. I hung of on fitting as I didn't fancy a major change before taking the car to Europe but now I'm back have bitten the bullit. I'm in quarantine till tomorrow so didn't take it for a run but will be out in it on Sunday for a trial. I'm also planning on fitting the 4 port Bosch fuel injectors soo too. Maybe after that I'll have to take a trip to Chesterfield for a remap or a swap to an aftermarket kit.

As it is on the drive it ticks over and revs nicely.
Guess I was lucky & found a zif socket that fits, Joolz should have no trouble remapping your 14CUX for 4 port injectors.

stevesprint

Original Poster:

1,059 posts

137 months

Thursday 3rd September
quotequote all
TRIUMPHBULLET said:
Hi all, I had a play in the car last weekend and found that the engine would cut out at almost 4000 rev/min, it is really smooth up to this point. The boost level shown at the time was 5lb/in2. Normally aspirated the car only reached the last but one bottom row even at 5000 + rev/min. the engine is a std 3.9, std cam and I have put Steve Sprints TVR 4.3 precat map in for now.
Had a look at the log and fuel map seems to hit the bottom row just before this. My passenger confirmed this as they were looking at the Rovergauge display.
If I want to extend the afm range of the map do I increase the Row scalar value (91 at moment) or decrease it to compensate. Also, will altering the Maf scalar offset value up (30 at moment), move the idle highlight up the table or down? I suspect even a modest alteration will affect the table so wish to tread carefully.
I know the fueling will need altering but that seems pointless till the afm scaling is correct.
Regards, Paul.

On full load you want the active row between 6.5 & 6.8 in the log files.

Increasing the AFM scalar pushes the active row downwards on the screen, (increasing currentFuelMapRow in the log).

Increasing the AFM Row Offset (at prom location 1C8) decrease the active row.

You’re right the slightest change to the row scalar does make a big difference to the AFR, because you’ll suddenly start using richer/leaner cells.

When your engine cuts out at 4,000 rpm are you getting any fault codes like 19. Throttle Pot to low and MAF to high? as I know that fault causes the engine to cut out at 4,000rpm. If its that fault code, what prom revision are you run as Land Rover desensitizes that fault code in the later revsions.

I suspect Mark is right and you are maxing out the 5AM too early and therefore I would recommend the Bosch 4.6 MAF, its bigger, more reliable and still availble new but would require a full remap unlike the 20AM.