Greetings,

I've been struggling with one of each of these cars, when tuning for roughly E50 blended fuel mixtures.  The actual adjustment of fuelling constants to compensate for the additional  value is perfectly fine.  The increase in performance is fantastic as all we have available is the equivalent of US 91 Octane.  

MED17.5 Setup

Golf 6 GTI - GT3076R
Stock Injectors
Stock HPFP (I know right, don't blame me) @ 165 bar
Walbro 450 LPH with revision pump controller and DC adjusted with an external FP gauge
Stock MAF
E45 fuel

MED9.1 Setup
Audi S3 with stock K04-064 turbo
S3 injectors
Autotech HPFP at 160 bar
Custom Rail Valve
DW65v Drop in
Custom 80 mm MAF
E45 fuel

As soon as it gets to 5500 rpm and the Median Injection Time goes > +-7.7 ms I get some savage throttle cut on the G6 and mild throttle closing on the S3.  At risk of mistaking correlation for causation, some quick calcs for injection window based on RPM and SOI/EOI:


5500 rpm = 91.6 rps = 0.01091 seconds per rev = 10.91 ms per rev = 5.45 ms per stroke, assuming that there is homogenous injection taking place and that the full intake stroke is being injected in. Now if the limiter for SOI is somewhere around 432 degrees, and EOI is roughly 60, I am reasonably assuming that this is degrees of crank before compression TDC, so 372 degrees of injection as the reasonable limit.  If one stroke takes 5.45 ms at 5500 rpm at 180 degrees, then that should leave 11.26 ms of injection time assuming injection begins 432 degrees BTDC and ends  for the latest at 60 degrees BTDC.  This is excluding any adjustment for the injector reaction time etc.

Am I far off in my assumptions?  Why am I suffering such severe throttle cut?  In both cases, the injection time is around 7.6 ms at roughly the same RPM I see the throttle start to close.  The boost and load request at this point is still high, LPFP is slightly above 5 bar as well.  All LDRLMX limiting maps have been raised, MIRL/MIOP raised and is inversely correct between the two.  Lambda control is around 5-8% additive for both.  I browsed through both the MED9.1 and MED17 FR to see what could cause it and I couldn't find the exact trigger for the throttle intervention (of course it exists, I just couldn't find it).

Both are running around 17 deg BTDC advance at the point of throttle close with minimal (<3 KR).

Is it likely that what I am experiencing is owing to exceeding the injection window, or owing to some kind of torque intervention?  I've maxed out the SOI limit at 432 degrees and still experience throttle cut. I have found that underscaling the MAF serves to make the problem worse.  The MED17.5 vehicle is at around 2300 mbar when the throttle closes, and 2600 mb for the Med9.1 S3.  The MED9.1 vehicle slowly begins closing the throttle and ends up at around 90%.  The MED17.5 G6 throttle cut is a lot worse.

Any help would be greatly appreciated.

Apologies for the crappy log pics, will upload the actual logs a bit later.

I'm sure someone with more knowledge on the med17 can confirm but sure an ECU hack is needed to overcome the limitation. I may be talking rubbish mind as never looked at one

I run E76 on my 2010 passat MED17.5 with no issues at all, juts KRKATE, advance and some minor fixes in "FKKVS"... made some Jetta MED17.5.2, Fusca (New Beetle) and other with sucess... I guess its no correlated to your blend.


Only DP and intake and there is 265~270Whp in those setups..original injectors, HPFP and LPFP (just waiting to discover when they will fail, but 20.000km later and more than 10 months and no problens at all)