00 S4 MAF/Vacuum Problem?

Hi all,

I've had a 'check engine' warning come on intermittently over the last 6
months. My service shop traced the code to either mass airflow sensor, or a
vacuum leak. They reset the warning, but it came back in 5 days.

Does anyone have experience with this problem? I'm told that it will take a
new MAF, or even a ECU if there is no vacuum leak.

The car is box stock with the exception of a K&N permanent air filter. 32k
miles, and it's had it's 36k service. Its running fine, idling smooth, and
pulling strong.

If people tell me that MAFs are notoriously unreliable, I'll just pick one
up and install. I'm a little hesistant to let me service shop start poking
around - I'm afraid they'll try to sell me a new ECU (computer).

Thanks in advance.

C

On Mon, 17 Oct 2005 11:28:44 -0400, "Carl Howarth" >
wrote:

>Hi all,
>
>I've had a 'check engine' warning come on intermittently over the last 6
>months. My service shop traced the code to either mass airflow sensor, or a
>vacuum leak. They reset the warning, but it came back in 5 days.
>
>Does anyone have experience with this problem? I'm told that it will take a
>new MAF, or even a ECU if there is no vacuum leak.
>
>The car is box stock with the exception of a K&N permanent air filter. 32k
>miles, and it's had it's 36k service. Its running fine, idling smooth, and
>pulling strong.
>
>If people tell me that MAFs are notoriously unreliable, I'll just pick one
>up and install. I'm a little hesistant to let me service shop start poking
>around - I'm afraid they'll try to sell me a new ECU (computer).

MAF failures are fairly common across the industry, it's the technology vs the
environment, MAFs can see plenty of nasties in the intake air that cause
eventual failure. And that K&N filter - if it's the one that uses oil in the
filter element - will likely raise the MAF failure rate.

The way to tell if the MAF is the root-cause of the MIL fault is to use a Vag
tool or emulator to read how far out of "normal" the ECU is trying to
calibrate the MAF. There's an acceptable tolerance range for the MAF. If the
MAF is outside of that range, that's when you start seeing the MIL light. You
can clear the error, but it'll come back in a day or two or three.

Again, dumping codes will identify the culprit pretty reliably. And Audi had a
"stealth warranty" on MAFs for B5 S4, at least. Mine was replaced even though
I was out of the warranty period...

"Carl Howarth" >
> wrote:
>
> >Hi all,
> >
> >I've had a 'check engine' warning come on intermittently over the last 6
> >months. My service shop traced the code to either mass airflow sensor,
or a
> >vacuum leak. They reset the warning, but it came back in 5 days.
> >
> >Does anyone have experience with this problem? I'm told that it will
take a
> >new MAF, or even a ECU if there is no vacuum leak.
> >
> >The car is box stock with the exception of a K&N permanent air filter.
32k
> >miles, and it's had it's 36k service. Its running fine, idling smooth,
and
> >pulling strong.
> >

Carl,
I've lost count of the number of times I've heard "MAF failure" and "K&N"
used in the same posting. I've talked to many folks with different
MAF-equipped cars with burned out MAF wires downstream from a K&N....my
brother included. Go to www.googlegroups.com and search the auto newsgroups
for those two things, grab a coffee and start reading.....
Cheers!
Steve Sears
1987 Audi 5kTQ - K&N now protecting my garage shelf from dust
1980 Audi 5k
1962 and '64 Auto Union DKW Junior deLuxes
(SPAM Blocker NOTE: Remove SHOES to reply)

Hi Steve and Daytripper,

I'd like to say thanks a bunch for your advice. I think I'll ditch the K&N,
grab a new MAF, and do it myself.

I'll google, and read up.

Again, many thanks!

Carl

"Steve Sears" > wrote in message
. ..
> "Carl Howarth" >
>> wrote:
>>
>> >Hi all,
>> >
>> >I've had a 'check engine' warning come on intermittently over the last 6
>> >months. My service shop traced the code to either mass airflow sensor,
> or a
>> >vacuum leak. They reset the warning, but it came back in 5 days.
>> >
>> >Does anyone have experience with this problem? I'm told that it will
> take a
>> >new MAF, or even a ECU if there is no vacuum leak.
>> >
>> >The car is box stock with the exception of a K&N permanent air filter.
> 32k
>> >miles, and it's had it's 36k service. Its running fine, idling smooth,
> and
>> >pulling strong.
>> >
>
> Carl,
> I've lost count of the number of times I've heard "MAF failure" and "K&N"
> used in the same posting. I've talked to many folks with different
> MAF-equipped cars with burned out MAF wires downstream from a K&N....my
> brother included. Go to www.googlegroups.com and search the auto
> newsgroups
> for those two things, grab a coffee and start reading.....
> Cheers!
> Steve Sears
> 1987 Audi 5kTQ - K&N now protecting my garage shelf from dust
> 1980 Audi 5k
> 1962 and '64 Auto Union DKW Junior deLuxes
> (SPAM Blocker NOTE: Remove SHOES to reply)
>
>