What happens after 1.5bar?

Mihnea Cotet mik at info.fundp.ac.be
Thu May 1 23:11:27 EDT 2003

Yes, there is a maxMAF map in the chips, it's a 5 by 1 points map, thus 5
MAF values for 5 RPM points, 2-3-4-5-6k RPM. When the actual MAF value
exceeds the programmed value, then comes into play a second map that looks
about the same but has lower values, thus lower air flow, which equals to
the issue of not being able to have boost exceeding a certain level until
the leak is fixed, or the maxMAF values raised.



At 21:41 1/05/2003 +0200, Richard Tanimura wrote:
>Interesting. Are you saying there is a MAF map as well? There must be
>because the MAF values have to relate to rpm and boost somehow. Right?
>-----Original Message-----
>From: 200q20v-admin at audifans.com [mailto:200q20v-admin at audifans.com]On
>Behalf Of Mihnea Cotet
>Sent: den 1 maj 2003 20:54
>To: Mike Miller; Dave; 200q20v at audifans.com
>Subject: Re: What happens after 1.5bar?
>Mike, Dave,
>I too think Dave is experiencing the overboost fuel pump cut-off but I'd
>rather bet on a small boost leak that triggers the cut-off.. The reason I'm
>saying this is because the overboost fuel pump cut-off is determined by air
>flow across the MAF, not actual boost, so no matter the boost level he's
>running, if the MAF signal is over the programmed max level, the fuel pump
>cuts off, I've BTDT and tested that in real time with an eprom emulator
>recently, just for the fun of it.
>So I'd suggest you Dave to check for leaks in the intake system, possible
>culprits are the IC to intake pipe hose and possibly the bypass valve too...
>At 11:39 1/05/2003 -0700, Mike Miller wrote:
> >----- Original Message -----
> >From: "Dave" <morpheus0213 at yahoo.com>
> >
> >
> > > Fellow Listers,
> > >
> > > After the turbo produces 1.5bar pressure what happens?
> > >  I'm trying to pinpoint my violent bucking problem, it
> > > seems as though when I get to 1.5bar the car will
> > > violently buck.  I'm guessing it's electrical because
> > > it seems to continue happening even when it doesn't
> > > reach 1.5 after the initial instance.  I am leading
> > > towards the ECU for that reason guessing that it must
> > > be reset to continue normally until 1.5 is reached
> > > again.  Of course I hope it isnt I'd rather not but
> > > another grand into the car right now but any input is
> > > appreciated.
> > >
> > > Thanks in advance,
> > > Dave Pianka
> >
> >This sounds like you are hitting the overboost fuel pump cutoff.  Once that
> >is triggered, you cannot get above 1.3 bar until the ignition is cycled.
> >Perhaps your boost gauge is off and you are seein gmore than 1.5bar to
> >it?
> >
> >mike miller
> >helmville mt
> >
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