NefMoto

Hello everyone!

I am trying to tune my car (2.7T S4) with 0280158040 injectors and I am running to some issues that I do not
understand completely. First of all I am running an OEM RS4 MAF sensor, so all the related maps have been
migrated over from a stock RS4 file:

- MLHFM
- MLOFS
- KFKHFM

KRKTE has been calculated based on the flow rate on the S4 wiki (1031cc) and set to 0.03119, then FKKVS
has been set to 1 in all cells. TEMIN has been set to 0.12.

Now the TVUB values are in order. There are several different data points floating around on the internet
and they are all different, but I've found an entry on nefmoto, which should be values from a real testbench
setup by ddillenger and these are the following:

8v   - 3.270
10v - 1.619
12v - 1.157
14v - 0.749
16v - 0.539

My base fuel pressure is 4 bar and with the vacuum line connected it is going down to 3.5bar so that should
be fine.

Now the problematic part is idle, which as far as I know should be mostly governed by TVUB, however even
with the configured TVUB values, the car is idling really rich and the ECU is pulling -10-15% fuel at idle.
If I raise the TVUB values higher and based on other dead time values on the internet that should be also
correct, it just goes even more rich to a point where the ECU tops out at -25% on both banks.

So I had to decrease TVUB still which seems to be wrong based on everyone else's data out there.

So now with TVUB configured as:

8v   - 2.376
10v - 1.627
12v - 1.083
14v - 0.699
16v - 0.560

The situation is better, but the ECU is still pulling fuel at idle a lot and after doing a long drive to calibrate
FKKVS, here is how it looks:

(https://i.imgur.com/a0udc3L.png)

It shows quiet well that idle is rich and then midrange is lean a bit, but based on my wideband log, WOT is spot on,
so I think something is not right, but I can't figure out what. TVUB being really off based on other's settings really
bugs me because it probably shows that something is not right either hardware-wise or calibration-wise.

I have replaced the MAF already to rule out a maf sensor issue, fuel pressure has been also validated both with a vacuum line
off and on on the regulator

So honestly, I am just looking for pointers at this point.

Thank you in advance!

Those injectors flow more at the pressure you are using, try 0.0283 Krkte and report back.

If I lower KRKTE to the suggested value, WOT leans out pretty badly.

What is your setup?

Do you also have RS4 Throttle, Intake etc. ?

I would also suggest to get a 3 Bar FPR unless you need the extra fuel. Its very cheap and comes as standard in the Audi S3 for example.
OEM Number 037 133 035 C

The Bosch 980 flows 1112ccm/min at 4 bar. When I use the KRKTE calculator it says 0,029302491 for that flowrate. You can try that with higher tvub values.

Hi.

It is an RS4 engine swapped from a rear-ended RS4, so I am running the oem RS4 throttle and intake.

0.029302 is still leaning out and as far as I know TVUB does not really affect WOT fueling, does it?

What bin file do you use? And what ECU?

RS4 (F or K) or S4 ?

As far as I understand it TVUB does affect even WOT fueling. Because its the deadtime of the injector it is added to every single injection event. Please correct me if I'm wrong.
But the effect is not that big, because on WOT runs you have 10 to 15ms of injection for example. So if you add 0.5 or 0.6ms it does not affect that much as it does on idle.

Try the suggested KRKTE with this TVUB...
8.0v 2.75
10v 2.09
12v 1.58
14v 1.19
16v 0.93

Correct

TVUB

RS4 F

Same. idle is pulling -25% and still idling at lambda 0.8. (My NORLA is 7), but partial and WOT is lean around 10-15%.

Maybe some logs?

I had same problem on 1.8T with EV14 (~550ccm)

Than I lowered TVUB to some really crazy low values, little work on FKKVS and it is fine

running good with this values?

A big question here , i not found this question ever in nefmoto!
Example for a 3 bar FPR , ww have 2.5 bar at idle with vaccum connected.
TVUB must be set at the value from bosch specification at 3 bar row from table or must be modified for 2.5 bar?

The goal of an 1:1 FPR is to maintain an constant differential pressure between the pressure inside the manifold and the fuel pressure.
At idle, you have a lower pressure than atm in the intake manifold, in your case 500mbar lower. Thats why your FPR is dropping the fuel pressure to 2.5bar. You still have 3bar of differential pressure.
So no, you use an 3bar 1:1 FPR, you have to look at 3bar row.


sorry, didnt saw your message until now. Yeah, running good, I made some fine adjustment in TVUB but not too much.