Hi all,

I'm stumped what to try next. On my '87 5000S Quattro I'm getting
Fault Code 2233 - Air Flow Sensor Reference voltage, or from
Bentley's:

Code: Location:
2233 "Reference (supply) voltage for air sensor potentiometer and
altitude sensor"

Problem:
"No reference voltage from Terminal 21 or ignition control unit to
Terminal 26 of fuel injection control unit"

Repair:
"Check wiring between electronic ignition and fuel injection control
unit using wiring diagram"

I've checked this wire, as well as wires between ECU (injection
control unit) and all related devices, such as air flow potentiometer,
temp sensor, cold start valve, idle stablization valve; and test each
device except the air flow potentiometer. I've also replaced the ECU
(injection, not ignition).

Before I replace the ignition ECU and start a massive wiring check,
can anybody steer me to a area that they think might be the root
cause? Oh, the behavior is that it idles high, random ignition
cut-out, and the cold start valve wasn't working (tho cold-start may
now be working -- it started okay just now, tho before it had been
requiring 30-60 sec of cranking before starting - hot or cold).

TIA,
Jaz

{ Please excuse the 'burp' when replying }
¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨"°ºOº°"¨

 

Sorry, no BTDT on this one.

Just a thought. Sometimes when there seem to be multiple symptoms the
cause ends up being a bad ground. Also, I didn't think that the '87 Q
NAs had a separate ICU (in the drivers kick panel on my '91 100Q). If it
does have this, some people have found that rain / water has migrated
somehow into the plastic bag that the ICU is enclosed in and has
corroded the multi pin connector. Cleaning often corrects the problems.

Seems that I heard that the ICU optimizes engine management but in the
absence of information from the ICU the ECU operates things in default
mode. This might be a SWAG.

You have really done your homework on this one.

Tony
'91 100Q 5spd

Jaz wrote:
> Hi all,
>
> I'm stumped what to try next. On my '87 5000S Quattro I'm getting
> Fault Code 2233 - Air Flow Sensor Reference voltage, or from
> Bentley's:
>
> Code: Location:
> 2233 "Reference (supply) voltage for air sensor potentiometer and
> altitude sensor"
>
> Problem:
> "No reference voltage from Terminal 21 or ignition control unit to
> Terminal 26 of fuel injection control unit"
>
> Repair:
> "Check wiring between electronic ignition and fuel injection control
> unit using wiring diagram"
>
> I've checked this wire, as well as wires between ECU (injection
> control unit) and all related devices, such as air flow potentiometer,
> temp sensor, cold start valve, idle stablization valve; and test each
> device except the air flow potentiometer. I've also replaced the ECU
> (injection, not ignition).
>
> Before I replace the ignition ECU and start a massive wiring check,
> can anybody steer me to a area that they think might be the root
> cause? Oh, the behavior is that it idles high, random ignition
> cut-out, and the cold start valve wasn't working (tho cold-start may
> now be working -- it started okay just now, tho before it had been
> requiring 30-60 sec of cranking before starting - hot or cold).
>
> TIA,
> Jaz
>
> { Please excuse the 'burp' when replying }
> ¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨"°ºOº°"¨

 

Yes, this one has both ignition and injection ECU's (must be CIS-III),
and today I tried swappig out the ignition ICU, but that had no
effect... still the 2233 fualt code. And each ECU is clean with no
contamination or corrosion. Tomorrow I'll check resistance ranges on
the air flow potentiometer.
OTOH, I must say that aside from the high idle, the runs well once it
starts.

TonyJ <tonyjNOSPAM@NOSPAMvisi.com> forgot to take the pills and typed:
>Sorry, no BTDT on this one.
>
>Just a thought. Sometimes when there seem to be multiple symptoms the
>cause ends up being a bad ground. Also, I didn't think that the '87 Q
>NAs had a separate ICU (in the drivers kick panel on my '91 100Q). If it
>does have this, some people have found that rain / water has migrated
>somehow into the plastic bag that the ICU is enclosed in and has
>corroded the multi pin connector. Cleaning often corrects the problems.
>
>Seems that I heard that the ICU optimizes engine management but in the
>absence of information from the ICU the ECU operates things in default
>mode. This might be a SWAG.
>
>You have really done your homework on this one.
>
>Tony
>'91 100Q 5spd
>
>Jaz wrote:
>> Hi all,
>>
>> I'm stumped what to try next. On my '87 5000S Quattro I'm getting
>> Fault Code 2233 - Air Flow Sensor Reference voltage, or from
>> Bentley's:
>>
>> Code: Location:
>> 2233 "Reference (supply) voltage for air sensor potentiometer and
>> altitude sensor"
>>
>> Problem:
>> "No reference voltage from Terminal 21 or ignition control unit to
>> Terminal 26 of fuel injection control unit"
>>
>> Repair:
>> "Check wiring between electronic ignition and fuel injection control
>> unit using wiring diagram"
>>
>> I've checked this wire, as well as wires between ECU (injection
>> control unit) and all related devices, such as air flow potentiometer,
>> temp sensor, cold start valve, idle stablization valve; and test each
>> device except the air flow potentiometer. I've also replaced the ECU
>> (injection, not ignition).
>>
>> Before I replace the ignition ECU and start a massive wiring check,
>> can anybody steer me to a area that they think might be the root
>> cause? Oh, the behavior is that it idles high, random ignition
>> cut-out, and the cold start valve wasn't working (tho cold-start may
>> now be working -- it started okay just now, tho before it had been
>> requiring 30-60 sec of cranking before starting - hot or cold).
>>
>> TIA,
>> Jaz
>>
>> { Please excuse the 'burp' when replying }
>> ¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨"°ºOº°"¨


{ Please excuse the 'burp' when replying }
¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨"°ºOº°"¨

 

I'm an idiot.

But Tom Chudzinski is not (sorry to post your name here, Tom, but you
deserve recognition for this)

Tom wrote to me and said:
"Are the fuses in positions 23 through 28 good? (perpendicular to the
main fuses in the main fuse box) Often the schedule in the fuse box
will say "unused" or "open" but . . . . . sometimes they are needed.
Some Audis use position 24 to power the CIS-EIII controls, some use
fuse 28. THEY MAY NOT BE "EXTRA" FUSES!!!!! Many useless diagnostic
dollars have been spent and many a bald man has been created over this
issue. Often the published repair manuals are incorrect in this area."

Sure enough, and I'm embarrassed to admit, I neglected to stuff a fuse
in position 28 despite that it obviously had contacts in the socket,
whereas the other 'spare' sockets had none (not to mention that long
ago I replaced my cracked fuse panel cover with one from a junk yard,
but when I dug out my original cover it clearly lists #28 as 'Engine
Timing'.) Sometime over the past months I must have used #28 as a
spare for another blown fuse, and just didn't but two and two
together.

Oof! Oof! Oof! (that's the sound of me kicking myself).

Thank you all for your help, Especially Tom who reminded me of the
DFC's and ultimately the fuse solution.

Humbly,
Jaz


Jaz <harbellburp@beer.com> forgot to take the pills and typed:
>Hi all,
>
>I'm stumped what to try next. On my '87 5000S Quattro I'm getting
>Fault Code 2233 - Air Flow Sensor Reference voltage, or from
>Bentley's:
>
>Code: Location:
>2233 "Reference (supply) voltage for air sensor potentiometer and
>altitude sensor"
>
>Problem:
>"No reference voltage from Terminal 21 or ignition control unit to
>Terminal 26 of fuel injection control unit"
>
>Repair:
>"Check wiring between electronic ignition and fuel injection control
>unit using wiring diagram"
>
>I've checked this wire, as well as wires between ECU (injection
>control unit) and all related devices, such as air flow potentiometer,
>temp sensor, cold start valve, idle stablization valve; and test each
>device except the air flow potentiometer. I've also replaced the ECU
>(injection, not ignition).
>
>Before I replace the ignition ECU and start a massive wiring check,
>can anybody steer me to a area that they think might be the root
>cause? Oh, the behavior is that it idles high, random ignition
>cut-out, and the cold start valve wasn't working (tho cold-start may
>now be working -- it started okay just now, tho before it had been
>requiring 30-60 sec of cranking before starting - hot or cold).
>
>TIA,
>Jaz
>
>{ Please excuse the 'burp' when replying }
>¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨"°ºOº°"¨


{ Please excuse the 'burp' when replying }
¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨"°ºOº°"¨

 

I'm an idiot.

But Tom Chudzinski is not (sorry to post your name here, Tom, but you
deserve recognition for this)

Tom wrote to me and said:
"Are the fuses in positions 23 through 28 good? (perpendicular to the
main fuses in the main fuse box) Often the schedule in the fuse box
will say "unused" or "open" but . . . . . sometimes they are needed.
Some Audis use position 24 to power the CIS-EIII controls, some use
fuse 28. THEY MAY NOT BE "EXTRA" FUSES!!!!! Many useless diagnostic
dollars have been spent and many a bald man has been created over this
issue. Often the published repair manuals are incorrect in this area."

Sure enough, and I'm embarrassed to admit, I neglected to stuff a fuse
in position 28 despite that it obviously had contacts in the socket,
whereas the other 'spare' sockets had none (not to mention that long
ago I replaced my cracked fuse panel cover with one from a junk yard,
but when I dug out my original cover it clearly lists #28 as 'Engine
Timing'.) Sometime over the past months I must have used #28 as a
spare for another blown fuse, and just didn't but two and two
together.

Oof! Oof! Oof! (that's the sound of me kicking myself).

Thank you all for your help, Especially Tom who reminded me of the
DFC's and ultimately the fuse solution.

Humbly,
Jaz


Jaz <harbellburp@beer.com> forgot to take the pills and typed:
>Hi all,
>
>I'm stumped what to try next. On my '87 5000S Quattro I'm getting
>Fault Code 2233 - Air Flow Sensor Reference voltage, or from
>Bentley's:
>
>Code: Location:
>2233 "Reference (supply) voltage for air sensor potentiometer and
>altitude sensor"
>
>Problem:
>"No reference voltage from Terminal 21 or ignition control unit to
>Terminal 26 of fuel injection control unit"
>
>Repair:
>"Check wiring between electronic ignition and fuel injection control
>unit using wiring diagram"
>
>I've checked this wire, as well as wires between ECU (injection
>control unit) and all related devices, such as air flow potentiometer,
>temp sensor, cold start valve, idle stablization valve; and test each
>device except the air flow potentiometer. I've also replaced the ECU
>(injection, not ignition).
>
>Before I replace the ignition ECU and start a massive wiring check,
>can anybody steer me to a area that they think might be the root
>cause? Oh, the behavior is that it idles high, random ignition
>cut-out, and the cold start valve wasn't working (tho cold-start may
>now be working -- it started okay just now, tho before it had been
>requiring 30-60 sec of cranking before starting - hot or cold).
>
>TIA,
>Jaz
>
>{ Please excuse the 'burp' when replying }
>¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨"°ºOº°"¨


{ Please excuse the 'burp' when replying }
¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨"°ºOº°"¨Jaz <harbellburp@beer.com>
forgot to take the pills and typed:
>Hi all,
>
>I'm stumped what to try next. On my '87 5000S Quattro I'm getting
>Fault Code 2233 - Air Flow Sensor Reference voltage, or from
>Bentley's:
>
>Code: Location:
>2233 "Reference (supply) voltage for air sensor potentiometer and
>altitude sensor"
>
>Problem:
>"No reference voltage from Terminal 21 or ignition control unit to
>Terminal 26 of fuel injection control unit"
>
>Repair:
>"Check wiring between electronic ignition and fuel injection control
>unit using wiring diagram"
>
>I've checked this wire, as well as wires between ECU (injection
>control unit) and all related devices, such as air flow potentiometer,
>temp sensor, cold start valve, idle stablization valve; and test each
>device except the air flow potentiometer. I've also replaced the ECU
>(injection, not ignition).
>
>Before I replace the ignition ECU and start a massive wiring check,
>can anybody steer me to a area that they think might be the root
>cause? Oh, the behavior is that it idles high, random ignition
>cut-out, and the cold start valve wasn't working (tho cold-start may
>now be working -- it started okay just now, tho before it had been
>requiring 30-60 sec of cranking before starting - hot or cold).
>
>TIA,
>Jaz



{ Please excuse the 'burp' when replying }
¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨"°ºOº°"¨

 

Eureka! Glad you got it running, Jaz. As I recall I think I did the same
thing on time when I was working on mine. Pulled out a "spare" fuse, and
then the engine didn't work right. I forgot how I finally identified the
problem, but it was a bugger.

Congrats...



--
Stephen Clark
89 Audi 100
Houston, Texas USA

See my Audi in the Registry at www.audiworld.com!

"Jaz" <harbellburp@beer.com> wrote in message
news:dmj8nvog6g2pip8ua5e4fo0f0983uq05jg@4ax.com...
>
> I'm an idiot.
>
> But Tom Chudzinski is not (sorry to post your name here, Tom, but you
> deserve recognition for this)
>
> Tom wrote to me and said:
> "Are the fuses in positions 23 through 28 good? (perpendicular to the
> main fuses in the main fuse box) Often the schedule in the fuse box
> will say "unused" or "open" but . . . . . sometimes they are needed.
> Some Audis use position 24 to power the CIS-EIII controls, some use
> fuse 28. THEY MAY NOT BE "EXTRA" FUSES!!!!! Many useless diagnostic
> dollars have been spent and many a bald man has been created over this
> issue. Often the published repair manuals are incorrect in this area."
>
> Sure enough, and I'm embarrassed to admit, I neglected to stuff a fuse
> in position 28 despite that it obviously had contacts in the socket,
> whereas the other 'spare' sockets had none (not to mention that long
> ago I replaced my cracked fuse panel cover with one from a junk yard,
> but when I dug out my original cover it clearly lists #28 as 'Engine
> Timing'.) Sometime over the past months I must have used #28 as a
> spare for another blown fuse, and just didn't but two and two
> together.
>
> Oof! Oof! Oof! (that's the sound of me kicking myself).
>
> Thank you all for your help, Especially Tom who reminded me of the
> DFC's and ultimately the fuse solution.
>
> Humbly,
> Jaz
>
>
> Jaz <harbellburp@beer.com> forgot to take the pills and typed:
> >Hi all,
> >
> >I'm stumped what to try next. On my '87 5000S Quattro I'm getting
> >Fault Code 2233 - Air Flow Sensor Reference voltage, or from
> >Bentley's:
> >
> >Code: Location:
> >2233 "Reference (supply) voltage for air sensor potentiometer and
> >altitude sensor"
> >
> >Problem:
> >"No reference voltage from Terminal 21 or ignition control unit to
> >Terminal 26 of fuel injection control unit"
> >
> >Repair:
> >"Check wiring between electronic ignition and fuel injection control
> >unit using wiring diagram"
> >
> >I've checked this wire, as well as wires between ECU (injection
> >control unit) and all related devices, such as air flow potentiometer,
> >temp sensor, cold start valve, idle stablization valve; and test each
> >device except the air flow potentiometer. I've also replaced the ECU
> >(injection, not ignition).
> >
> >Before I replace the ignition ECU and start a massive wiring check,
> >can anybody steer me to a area that they think might be the root
> >cause? Oh, the behavior is that it idles high, random ignition
> >cut-out, and the cold start valve wasn't working (tho cold-start may
> >now be working -- it started okay just now, tho before it had been
> >requiring 30-60 sec of cranking before starting - hot or cold).
> >
> >TIA,
> >Jaz
> >
> >{ Please excuse the 'burp' when replying }
> >¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨"°ºOº°"¨
>
>
> { Please excuse the 'burp' when replying }
> ¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨¨"°ºOº°"¨"°ºOº°"¨

 

Good to hear you have it figured out and cheaply at that.

I guess I did have a BTDT. Had the same experience and should have
thought of that.

slapping self in forehead.

Tony
'91 100Q 5spd

Stephen Clark wrote:
> Eureka! Glad you got it running, Jaz. As I recall I think I did the same
> thing on time when I was working on mine. Pulled out a "spare" fuse, and
> then the engine didn't work right. I forgot how I finally identified the
> problem, but it was a bugger.
>
> Congrats...
>
>
>