[Biturbos4] driving without working MAF

David Kavanagh audiguy at gmail.com
Fri Jul 23 07:35:27 EDT 2004

FYI. I checked for codes again last night. None, but the block 32
values (fuel trim) were
-4.5% 15.6% -4.7% 16.4%
The higher numbers are the multiplicative fuel trim. They adjust
higher RPM trim and values > +/- 10% indicate a MAF that is out of
whack. (the lower values are the additive fuel trim and values > +/-
10% would indicate a vacuum leak).... that info from Andy at Ross-Tech
(at the link provided below)
So, I'll just have to wait for it to get bad enough to throw codes
that cause the CEL (or MIL if you are persnickety) to come on.


On Thu, 22 Jul 2004 00:54:39 -0400, David Kavanagh <audiguy at gmail.com> wrote:
> This link should provide a bunch of info for checking the MAF and
> understanding how the ECU tries to correct via fuel trim.
> http://forums.vwvortex.com/zerothread?id=1201806
> I just checked my codes again tonight (after resetting a couple days
> ago) and got.
> 2 Faults Found:
> 17538 - Fuel Trim: Bank 2 (Mult): System too Lean
>         P1130 - 35-10 - - - Intermittent
> 17536 - Fuel Trim: Bank 1 (Mult): System too Lean
>         P1128 - 35-10 - - - Intermittent
> I forgot to check measurement block 032 (which would have told me how
> much the ECU had to correct for the MAF) I'll check those next time I
> see these codes.
> BTW, I have a '00 A6 2.7t 6-speed... (wouldn't mind an S4 though!)
> ----- Original Message -----
> From: j y <jimnetpa at yahoo.com>
> Date: Wed, 21 Jul 2004 15:09:55 -0700 (PDT)
> Subject: Re: [Biturbos4] driving without working MAF
> To: David Kavanagh <audiguy at gmail.com>
> Cc: biturbos4 <biturbos4 at audifans.com>
> Hey David,
> Good stuff.
> What year is your S4? I have a Y2K and that's the MY where most of the
> failures have occurred I believe. I have a VAG and will check block
> 003 - if my MAF is working properly - what code should it be
> displaying?
> So far (fingers crossed), I have no CELs and I'm a stage 2.5 (LeBree
> DPs, AWE TWIN2 dual exhaust, GIAC-X chip, GIAC Tip chip, AMS TBB,
> Stratmosphere DVs, SAMCO hoses, EVO intake/airbox) tip with 75k mi
> (i've had it since day one).
> jy
> David Kavanagh <audiguy at gmail.com> wrote:
> Thanks for all of the replies. Here is some more data (for the
> curious). Back in April, it had a CEL. I got the VAG-COM printout from
> the independent dealer I was working with and it showed a fuel trim
> adjustment was made and some lean indications. Right away I suspected
> the MAF, but they cleared the codes and said, let us know if it comes
> back. Well, 3 weeks ago, it came on again, but I couldn't get into the
> shop until the following Monday, and by then the CEL was out. I had
> them hook it up anyway and they said there weren't any codes.
> I got my own VAG-COM a week ago and hooked it up right away. I saw
> some codes, 1 about a lean condition and several misfire codes. I ran
> a 2nd gear acceleration test 2 days ago with the VAG-COM logging RPM,
> MAF output, engine load and ignition timing (block 003 for those with
> the tool). It showed a low MAF output
>  signal. So, I think it has been
> failing slowly over time and the ECU has been correcting by adjusting
> the fuel trim settings. I'll have to hook up and look at those to see
> how far away from zero they are. (though, it its normal for them to be
> non-zero).
> Without a related code, the dealer (and Audi) won't replace it under
> the extended warranty for that part. I'm not terribly interested in
> replacing it out of pocket. Given how it is failing, I think I'll just
> take my chances (and bring my VAG-COM along). I have the phone # for
> the Audi dealership in Ottawa (where we are going) and I'll hope for
> the best.
> Thanks!
> David
> --
> '00 A6 biturbo 6-speed
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> --
> '00 A6 biturbo 6-speed

'00 A6 biturbo 6-speed

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