Timing being pulled back? With links to the graphs

Mihnea Cotet mik at info.fundp.ac.be
Wed Dec 4 21:29:59 EST 2002


Where did you get that statement about the ECU not using the MAF sensor
above 4200 RPM? I am sure this is false because I have seen more than once
that the fuel/timing maps are a function of MAF vs. RPM, i.e. Lambda= f
(MAF/RPM) or ign adv= f (MAF/RPM) and that they cover the full engine RPM
range. If the MAF sensor had been disabled, then maybe the maps would have
only been from 600 to 4200 RPM, which isn't the case. There are also other
legends about the Motronic systems on these lists, such as the MAP sensor
function, and I mean the MAP sensor isn't involved in anything else but
controlling boost pressure, no timing (vacuum advance/boost retard) and no
enrichment either are based on the MAP sensor in an Audi 20vt I5 Motronic
system. So this leads us to the point where a MAP sensor upgrade isn't
really necessary for people who like to "play" like you with stiffer WG
springs and no WGFV. BTW, where did you get your 2.3 Bar spring from? I'd
like to have one on my engine so I can play a bit with higher boost
settings without having to mess with the chips in my ECU yet.... Yes, I'm
playing with chiptuning software and I know quite a few things about the
way a Motronic works and when I say something I can prove it, otherwise I
won't say it... :)

Thanks for your answer,


At 19:32 4/12/2002 +0100, Claus Vegener wrote:

>I always use 98 octane even if I have to drive long way
>to find it. (I have all DK 98 octane stations on my Garmin Streetpilot)
>For competition - just to be safe because the engine gets hot -
>I use the 98 + 30% of a ochtanebooster home brew of
>using Xylene (117 ocht)
>but at the same price I also use Sunoco 102+ to mix with.
>The only events I had a timing delay was with the original engine
>3B . but worn - pumping oil through the breathe hose to turbo intake.
>The oil mist decrease the octanerating and gives a temporary
>loose of maybe 50 Hp. And after the run oil was dripping
>out of the IC. After loosing some runs for that reason, I
>installed a not-so-worn 3B (76.000 km) instead of the 250.000 km.
>The ECU uses only the MAF up to 4200 rpm. At boost and above
>the dutycycles for fuel injectors is calculated based on rpm and boost.
>(That's why the chips and injectors have to fit together and fuel pressure)
>If one want to mesh with high boost, I advise to install a O2 meter
>just to follow what's happen. The signal can be taken from the original
>but take care - the cord have a tinny shield outside the engine bay..
>----- Original Message -----
>From: "Brian Link" <BrianL at starsys.com>
>To: <200q20v at audifans.com>
>Cc: <vegener at post7.tele.dk>
>Sent: Wednesday, December 04, 2002 6:31 PM
>Subject: Re: Timing being pulled back? With links to the graphs
>Now everyone is going to shim their wastegates down and disconnect the
>WGFV :)   Clearly your car is doing fine at 22 - 23psi without
>detonation.  Which doesn't make much sense to me.  How can our 9.3 : 1
>compression engine not detonate at 22 - 23 psi on pump gas.  What fuel
>do you use in Dk?   I am forced to run 91 octane with 10 - 15% ethanol
>here in Colorado.  Do you know if your cut off was due to your MAF
>signal maxing out?
> >
> >Yes Patrick
> >That's my very own experience.
> >Changing from k24 to G T04/50 and adjusting fuel pressure watching my
>O2 readout - all other unchanged. 0-60 Mph from G-TechPro changed from
>5.52 sec. to 4.96. The WG springloaded and not changed.
> >
> >I have a problem with the IA st. 4 running into over boost cutting my
>fuel supply. My chips didn't >not have the falling slope as it should
>from  24 (2.6 Bar abs) to 18. It stays stable until cut off >at 6.000
>rpm. I have placed a dyno run together with
> >a) original 220 (226 - my case) Hp and IA III with the
> >timing retard before reaching 277 Hp
> >b) Hp and Nm curves
> >c) The flat boost not dropping but giving a serious  acceleration until
>cut-off New pages are http://home7.inet.tele.dk/vegener/audi
>200q20v mailing list
>200q20v at audifans.com

More information about the 200q20v mailing list