Instructions to change fuel maps on 14CUX Griffith, Chimaera

[davep]

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]

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]

stevesprint said:

... while bimbling along as I do, unlike you at Millbrook

Five years ago ...

[Donkercam]

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]

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]

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]

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]

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]

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]

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]

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]

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.

[blitzracing]

Colin has just updated RoverGauge to allow you to see the fuel map data in decimal by adding an extra button in the options menu. This means for us mere mortals who don't naturally think in Hexadecimal, we can look at the fuel cell values and easily understand them. Basically you have 255 fuelling steps available from no fuel at 0 to maximum fuel at Hex FF. This can now be shown as 0 to 255 in decimal, so it becomes much clearer to how you map is configured. My map here is quite a good example where you can see the fuelling amount increase as you travel down the map as the AFM volume goes up, and across as the RPM rises. In my case peak fuelling of 255 occurs at 3850 to 4401 RPM on the bottom row (max airflow and the highest volumetric efficiency point with my cam) and then drops off slightly to 253 as the engine starts to struggle to draw the air in fast enough, and volumetric efficiency drops, so you need less fuel per cycle to maintain peak power.




Latest RoverGauge is in either 32 bit or 64 bit windows. If you dont know what version of windows you are running go to the search box and type "about" and select about your PC. You will find it under device specifications system type.

Latest version here:

https://github.com/colinbourassa/rovergauge/releas...

[davep]

stevesprint said:

... Are the pressure pulses the vacuum in the inlet?

Very informative article in this month's Sprint (March 2021, pages 19 -24) covering inlet manifold design, by Sam Cook and dyno tested by Joolz; it's well worth a read.

Although the described project involves a Speed 6 air box project the same principles are also applied in our Rover /TVR V8 Plenum and inlet manifold tract design. But instead of variable inlet length tuning used on the Speed 6 setup the Rover V8 employs a combination of direct and cross-over tracts of different lengths, which in combination with the firing order, ensures well balanced inlet pressure pulse wave tuning.

[spikep]

My long term trim is staying on zero and short term is going full scale in the opposite directions.




What do you think I need to do. I’ve disconnected the ECU to reset it but it comes back like this.
The ECU seemed to bring the trim in quicker than the 2 minutes though.

[blitzracing]

If you have zero long term trim, then you are likely not to be getting the engine hot enough for the long term trim to set. Starting from scratch the short term trims may well max out, but the long term should move bit by bit over a couple of minutes until the short term starts to cycle around the mid point. Dont touch the throttle, just let the engine idle at full running temp. typically this process takes about 2.5 mins but it will depend on how far the long term trim has to move. Its worth noting the two sides of the V8 dont fuel evenly as you have an air intake on one side, not down the middle. If your long term trims are at maximum for either side, then you do have an issue.

[spikep]

Hi Mark,

Thanks for the comment. I found the lambda extender cable to the odd bank broken on the Griff. I’ve repaired that until I can get a new one. This has cured the fault above.

Now After a reset, engine idling and up to temp. Both long term trims work their way to 100% Max less fuel and the short term trim’s are both moving around the -70% to -80% mark.

Am I now over fuelling? And if so, how do I turn it down? I’m running the chip you sent me last year and the engine does run smoothly.

[blitzracing]

If its one of my 3.9 maps the white map is TVR unmodified, the green non cat map is the one I've worked on so I would not be looking at the map as the first point of call. Do you recollect why we where trying another chip? Its worth checking the AFM standby voltage, as if it drifts upwards the engine will over fuel. To do this put a test meter and Insert the negative probe into the Red/Black wire (sensor ground), and the positive into the Blue/Green wire (Airflow signal). Now turn on the ignition, and the voltage should spike to near 5 volts as the hot wire heats up, then settle to 0.3-0.34 Volts. I had not realised how important this voltage was with no airflow, but now i've had a few faulty AFMs to play with it has shown if this voltage is wrong, the whole output is wrong up the scale. Fuel pressure is another thing, if the vacuum pipe is not connected to the regulator the fuel pressure is too high. and so it over fuels.

Edited by blitzracing on Wednesday 24th March 18:16

[CGCobra]

Hi all, hope everybody is safe and well in these difficult times.

Not been around for a while, just looked back and found it was 2016 last time I was on, can't believe it's been so long.
Unfortunately work and other life issues has kept me busy so I've not been as active with this project as I'd hoped.
I've just started to get back into it as I've recently been made "un-busy" but found the computer I was using back in 2016 is no longer working so need to set everything up on a new PC, problem is I've found that many of the links I was using in the past now I just get "Not Authorized to View This Page [CFN #0004]". Have these all been locked away now or am I just looking in the wrong place?

I have the latest RoverGage, some nice improvements since I was last involved, thanks Colin & Dan.
Also got the latest TunerPro and definitions and that seems to work with the bins I have from 2016 however it seems the 14CUX Toolkit is no longer around. Is there an alternative?

[blitzracing]

Toolkit is here for you:

https://www.dropbox.com/s/bttvzamiijrm8cg/14CUX%20...