NefMoto

I have a tune that is getting positive deviation limp when boost is ramping very slowly (WOT at low rpm)

It has a scaled MAF file (85mm), and a very restrictive stock intake.

According to the FR, the positive deviation diag is MinError here:
(http://nyet.org/cars/images/dldlr-ldra.png)

So according to this, to get positive deviation, you need

1) B_ldr (PID active) true
2) B_ldob false (assuming always true for S4, since KFLDRX0 is all zeros)
3) B_ladan true (rpm over 2600-3000, depending on ambient pressure)

(http://nyet.org/cars/images/B_ladan.png)

4) rl_w (load) > SDLDRA (84.75)
5) lde > EDLDRP (100mbar)
6) ldimxak_w>=TVLDIMX (which doesn't exist in Mbox, but TVLDMX does, which i assume means WGDC>=95%)

7) all of the above true for > TDLDRA seconds (there are two TDLDRA's in Mbox, one is .65, the other is 1.5)

I am thinking the combination of slow ramp and scaled MAF is causing this to occur in my tune. Comments?

Does it only happen in tall gears when you are lugging the engine?

Generally, yes, but I can make it happen in almost any gear except 1st by lugging it.

why not just max out those settings?  i bet it wouldn't take 10 seconds...

Don't like disabling safety features w/o fully understanding them, in case I'm overlooking something important.

And to be specific, I have a bunch of old logs that SHOULD have triggered positive deviation (according to my understanding of dldr-dfpm-ldo) but did not. Makes me wonder if I understand positive deviation at all :(

Log of 3rd gear lug, and limp -> 10% wgdc

(http://nyet.org/cars/images/nyet-8-5-2011_8-02-01_PM-neg-dev.png)

Some interesting tidbits from the various bins that I have

R (a6 2.7t) is pu -240 to 280, rpm is 3000-2600
F (rs4) is 280 to -420 (inverted x axis!) rpm is 3000-3400 (K04s!!!!)
G (s4 2.7t) is pu -320 to 280, rpm is 3000-2520
M (s4 2.7t) is pu -420 to 280, rpm is 3000-2600

They're all 2x1 maps (so only two points, so just do simple interpolation to find output rpm)

The output is a single RPM value based on pu.... where pu is between 280 and -420

notice on the F box, the x axis (and output) is inverted, so the lower the pu, the higher the RPM threshold still.

Since this is a K04 tune, I am probably going to take the RS4 values.

also, it seems the R-Box TDLDRA is 3.0 vs 1.5 seconds
TLDLRA2 is the same for all the stock images I have (0.65) seconds

are you getting a positive deviation code?

actual never exceeds desired per your posted log - correct?

i've dealt with torque limit codes before related to MAF readings as well as boost deviation codes related to free flowing exhaust causing boost to ramp too quickly for stock boost diag.

I reduced MAF scaling and bumped up NDLDRAPU and SDLDRA and the problem went away...

Update: on a another car I had to bump TDLDRA2

Related thread

http://nefariousmotorsports.com/forum/index.php?topic=7524.msg69342#msg69342