NefMoto

Hello, gentlemen! :)
Yesterday I was looking through RKTI 11.40 and found one interesting map -> FRLFSDP. If I understand it correctly now we have the ability to change AFR based on boost?? Or is this only for returnless systems? Does o2 sensor interfere with this map?

For example I change 1.00000 to 1.20000 at -1200 hPa. Does that mean that I enrich my AFR at 1800 hPa of boost?? (in documentation it is said that -1200 hPa is equal to 1800 hPa of boost minus ambient 600 hPa)

And another question: If average ambient hPa is 1000 why bosch chosen 600?? I don't get it... So, if I want x axis to show hPa based on ambient 1000 hPa, should I just use offset of -400 ??

And one last question: What is the difference between TEMIN and TEMINVA?

It is a correction for the return-less fuel system.  It is calculated before the 02 correction is added/

Rick

This is all to do with the mysterious wall-film degradation phenomenon which I hadn't ever come across with respect to internal combustion engine matters until I read Greg Banish's book and then subsequently found it in the funktionsrahmen. RKTI states this:

"The threshold value TEMINVA is differentiated from TEMIN with a cold engine when the wall film degradation is not properly emulated by the thinning-delay because te_w limits TEMIN".

My limited understanding of the situation is that with a hot engine, there is evaporation from the walls of the cylinders (as you would expect) which degrades the wall-film. This is another variable which if not managed, can affect the amount of fuel vapour available for combustion and thus lambda. The aim is to ensure the quantity of fuel on the cylinder walls remains in equilibrium with the quantity of fuel evaporating so there is no net change and it removes one variable from the multifarious lambda adjustments being made.

Wall film degradation cannot be measured so instead it is modelled/estimated. The ECU checks the model and adjusts the amount of fuel injected accordingly to maintain the status quo. I guess that's where these  'thinning delay' times come into the picture.

When the engine is cold, there is less evaporation from the cylinder wall and thus less thinning of the wall film so the thinning delay time is short-circuited by the minimum injection time... or something.  :-\

TTQS

Ok... hm... so... um... TEMINVA is applied when engine is cold and TEMIN when engine is at normal temp?  ???

Hmm. Not sure. I've reached the limit of my basic knowledge, I'm afraid. There are more references to the wall film degradation in module ESUK 9.70, so I might have a look at translating that to understand it better.

TTQS

Thank you, TTQS :) I'm trying to completely define RKTI so I could understand it when and how maps are applied... :)

BTW: At least in my file TEMINVA is lower than TEMIN. So logically thinking TEMINVA should be applied when engine is hot, or something

I am going to resurrect this since I have a conflicting info on what's "fuel cutoff" is in our engines. Some folks say that when our engines decelerate and engine enters "SA" mode (fuel cutoff), the injectors should stop working altogether but this is not what I am seeing in my car.

My car uses TEMIN instead to power the injectors but doesn't ignite the mixture or so I believe anyway seeing that I am getting my wideband maxxed out. This means that there is tons of oxygen in the system which might mean either very lean combustion or no combustion at all.

In light of information contained in this thread, I start to believe that our cars indeed inject TEMIN amount of fuel wet/lubricate/cool the cylinder walls instead of "0.00 ms" as some think.

Masterj: TEMINVA is used on cold engine when the gas is not evaporating while TEMIN is used on hot engine where it is, so a TEMIN amount of it needs to be injected in situation when calculated fuel mass falls below TEMIN threshold. Like when you're decelerating with closed throttle.

if you injectors were still injecting fuel but ignition was not active, you would get raw fuel into the exhaust (and by O2 sensor).
If you have a cat, this fuel would be ignited in the cat.

And I don;t believe your O2 would read very lean. Consider went you run so rich all the isn't burnt.

My conclusion on ignition part was purely speculative and it would make sense for the car to keep igniting the mixture even if it is extremely lean.

Interesting... So maybe it is possible to set both TEMINVA and TEMIN to 0s so when decelerating we wouldn't use any fuel at all?

There shouldn't be fuel dumped when decelerating, independent of TEMIN setting.
At least as long as you did not make other changes that affect the value of B_sa.

I need help to really bone out how this map is used and how to correctly tune it, I have made changes logged but I cant seem to crack the code on this one. I have a feeling this could just be errors in my definition either in Winols or in the frkte_w variable in my logger definitions.

(http://img706.imageshack.us/img706/311/frlfsdpfrdia.jpg)

My understanding as of now: the input dpus_w(pu_w - (ps_w * vsfpses), delta intake pressure) changes the scaling on KRKTE, simple as it looks in the diagram.

This is my current FRLFSDP(stock) and KRKTE:
(http://img826.imageshack.us/img826/2853/frlfsdp.jpg)

And definition on FRLFSDP:
(http://img337.imageshack.us/img337/9859/definitions.jpg)

This is a 3rd gear pull with these settings, frkte_w goes up to like 0.109? Thats over 3 times the original KRKTE?
(http://img802.imageshack.us/img802/9153/bische120120829044146.png)

You see it hits the roof at around ~2100mbar, but according to my file/definition it should cap at -300mbar?

This is my frkte_w logger definition:
frkte_w, {}, 0x384AEA,  1,  0x0000, {ms/%}    , 0, 0,   0.00111111,      0, {Faktor Umrechnung rel. Kraftstoffmasse rk in effekt. Einspritzzeit te}

Attached the log also.

Looking at the graph you posted. At one bar of boost, he variable is exactly double the ambient figure. this is correct. 0.0525 vs 0.105

How do you mean it is correct?

The rail pressure is lowered by a little more than 1/4, compensated with tripling the injection constant? Can you show me how this is calculated, because according to my understanding this should produce 1.20*0.032967=0.039560 frkte_w

A KRKTE of 0.039560 with a pressure drop of ~1200mbar is very close to what the calculated KRKTE should be with my injectors and ~2.8bar fuel pressure.

Major overshooting setpoint followed by a -22% 02 correction tapering to ~-15% troughout the pull:
(http://img837.imageshack.us/img837/9153/bische120120829044146.png)

That is right.

I think you have KRKTE wrong, what address/factor are you using?

Please look at my post here: http://nefariousmotorsports.com/forum/index.php?topic=2418.msg22745#msg22745 (http://nefariousmotorsports.com/forum/index.php?topic=2418.msg22745#msg22745)

What about it? It has NO useful information to do with this post.

16bit lohi, 1D744, 0.000111

I have ran some different tests, and I have found the problem. The problem is the stock axis, it is way too short and when I run above/under the axis the ECU will extrapolate the curve, I believe this is done to prevent the mixture from running uber lean in the basic calculation if the boost would spike or just being able to build alot higher than requested in the stock calibration(0.6bar boost in my case).

It does however seem to hit a roof at ~2150mbar, I would suspect this is some 8bit cap but im not too good regarding that stuff.

Here is a fast cook up I did:
(http://img94.imageshack.us/img94/2779/frlfsdp2.jpg)

Which resulted in this:
(http://img269.imageshack.us/img269/6080/bische120120827043237.png)

I will refine this with better calculations and post the results.

Ok, here is my new calculation:
(http://img607.imageshack.us/img607/9470/frlfsdp3.jpg)

Lets break it down:

1131cc@4bar = 894cc@2.5bar(4bar - 1500mbar)

1131 / 894 = 1.2651

That is how the stock values are calculated IF they were to use the standard -1200 -1000 -800 -600 -400 -200 axis mentioned in the FR, the axis found in my binary is actually that one divided by 4 for some weird reason. If I enter that axis, all stock Z values lines up with the calculation I did above.

As for the KRKTE, I just simply divided old injector flow with new flow and used that factor to multiply the old KRKTE.

I have a good feeling about this one and I hope to finally get my fueling dialed, so I can start tuning for horsepower.

Forget about my last posts. The stock axis IS correct, however my definition was wrong and showing the axis divided by 4.

I changed that up and started tuning, and even with the right calculation from the FR I was getting bad results. I now have it pretty much spot on after ALOT of trial and error.

(http://img28.imageshack.us/img28/7638/bische120121014193050.png)

(http://img835.imageshack.us/img835/4932/frlfsdp4.jpg)

Im attaching a small excel sheet I made to calculate the FRLFSDP and KRKTE, if someone is tuning a returnless system please try it out and see how it works for you.

hi!
I'm considering changing my standard fuel pressure regulator (3bar) with a 4 bar one, on my TT 1.8T 225.
at the time I have only map and filter. is useful to change the fuel pressure regulator?

in attached my FRLFSDP. in this table there are only 1.0000

if I understand the rule to fill this table (http://nefariousmotorsports.com/forum/index.php?topic=460.0)
FRLFSDP pdr evmes = V / (pdr akt + (pu-ps))
Where in pdr evmes = absolute pressure in the fuel circulation upstream of the injection valve at measuring Qstat
(3000 hPa)

in my case ( i think ) FRLFSDP know id = 1 = V 3/3

will i have to replace 1.00000 with V4 / 3??

I also read that I have to increase by 15% KRKTE,  is ok?

Thanks in advance
Daniele

i have tri to use it, but probably I made a mistake

any help for me?

Dan,

This map is only for cars with returnless- static fuel pressure. They need compensation in the required fuel mass modeling because the effective flow rate changes with intake manifold plenum pressure.

Your TT has a 1:1 ratio fuel pressure regulator- as such, the pressure delta between fuel being injected and the air stays constant. This means that no correction is needed and that is why your table is 1.00 everywhere.

You probably won't see this as it's an old post but might as well answer the question for posterity's sake.

thanks for your replay
I would like to mount a 4bar fuel pressure regulator on my TT 225
now i have understand that i need to change only KRKTE and kvb

http://nefariousmotorsports.com/forum/index.php?topic=5079.msg49155#msg49155

Fuel pressure change will also affect to TVUB values. So you must also correct those as well.