Fwd: Re: Timing being pulled back? With links to the graphs

Mihnea Cotet mik at info.fundp.ac.be
Sat Dec 14 11:26:56 EST 2002

Well, Claus, now I have the verdict and this proves that either you didn't
remember correctly what Ned told you, or Ned told you BS or Ned doesn't
know what the chips are doing????

Here is the answer WRT MAF sensor (I did a copy/paste of what you wrote to
me and sent it to him) from a person I know in Germany and who is a Dipl.
Ing. in engine management systems (also chiptuning) and who's a tuner himself:

""absoluter quatsch. ich habe die damos beschreibung von bosch mit allen

So this means that the ECU uses the MAF sensor from idle to redline... I'd
rather spend 4 years looking at the maps inside the chips than reading
Probst's book because maybe he's right on the basics and on general ECU
description, but when it comes to the 20vt engines Motronic systems, it
just ain't right.



>>Well Mihnea - long story
>>I could be wrong.
>>I have checked all my mails with Ned without finding the
>>exact statement - so misunderstandings from phone calls may exist
>>but I have had this opinion for a quite long time and some other things
>>seems to convince me in that opinion
>>When the engine is accelerating you have to accept, that the ECU use
>>look-up tables with different input other than closed loop -
>>and feed back - from the Lambda.
>>There is a lot of talking about old type Lambda and wide band sensors
>>(not used for Motronic year 90) usable at any load.
>>So my guess is, that closed loop (feed-back) is not possible at
>>a lot of running conditions.
>>Charles O. Probst in Bosch Fuel Injection & Engine Management mentions on
>>page 36 Pulsed Injection - Full Load Acceleration
>>that the WOT switch disables the air-flow signal and base the fuel
>>enrichment solely on rpm.
>>To my opinion he should have written "on rpm and boost" too !!
>>I am sure temperature and boost are input to tables too.
>>My own experience is,
>>a) that when cruising at constant speed
>>the Lambda changes lean-normal-fat some times a second - all the time. If
>>you start pulling up-hill or accelerating
>>  the mixture is enriched showing the use of tables and not closed loop ?
>>b) at very hard acceleration - if the fuel pressure is too high -
>>the engine hesitates close to 4800 rpm and wont go to 7000.
>>Lowering pressure fix this problem. The Lambda is not able to
>>adjust. Just show fat mixture. But coasting and idling is still fine.
>>To be honest - the only doubt I have is whether I was told 4200 or 4400
>>rpm :-).
>>But I have to admit, that measured air escaping due to un-tightness also
>>give problems at acceleration.
>>MAPsensor upgrade?
>>If the boost can't be measured - the fuel can't be calculated -
>>to my opinion and a over-boost condition would arise.
>>A 2.0 Bar sensor delivers 5.0 V from 2.0 Bar and up to damage. The boost
>>chip run out of tables?
>>WG spring: I bought it from a Danish manufacture of springs.
>>I choose a length of 48 mm close to 2 "; a diameter 46 mm
>>as the original and coresize is 5  mm. And made the perch adjustable. You
>>can only compress a few mm with your hands.
>>Test-drive carefully watching boost in a high gear.
>>The real reason for playing with WG springs were the break down of my
>>Garrett turbo. I had to re-install my k24 and I didn't had
>>a standard MAF, only my RS2 MAF. So in order to save the live
>>of the k24 with the IA V set-up at 2.7 Bar I want to run at max 2.4 Bar -
>>and that works real great with the 3 Bar chipset, RS2 injectors and MAF.
>>I am interested in the truth about chips and ECU so please inform an
>>correct me.
>>I have decided, that next time I want to enhance my car, it should be
>>based on user programmable
>>systems in order to get rid of the restrictive Motronic.
>>Like a 034 from Javad perhaps for my Urq WR engine.
>>But 5 coil ignition is not released yet - ...
>>----- Original Message -----
>>From: "Mihnea Cotet" <mik at info.fundp.ac.be>
>>To: "Claus Vegener" <vegener at post7.tele.dk>; "audifan20v"
>><200q20v at audifans.com>
>>Sent: Wednesday, December 04, 2002 9:29 PM
>>Subject: Re: Timing being pulled back? With links to the graphs
>> > Claus,
>> >
>> >
>> > 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,
>> >
>> > Mihnea
>> >
>> >
>> > At 19:32 4/12/2002 +0100, Claus Vegener wrote:
>> >
>> >
>> > >Brian
>> > >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
>> > >http://www.team.net/sol/tech/octane_b.html
>> > >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..
>> > >
>> > >Claus
>> > >
>> > >----- 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
>> > >
>> > >
>> > >Claus,
>> > >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?
>> > >
>> > >Brian
>> > >
>> > >
>> > > >
>> > > >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
>> > >
>> > >
>> > >
>> > >_______________________________________________
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>> > >200q20v at audifans.com
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>> >
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