[V8] "Major Surging"

Tue Jul 27 07:37:26 EDT 2004

Try this, these are my old notes on surging....

Mike LaRosa
ex multi V8 owner...

Hi Everybody,

Every once in a while I peruse through the archives for V8 stuff.

I noticed all the questions about surging.

It seems you guy's are going down the correct path....

DON'T REPLACE PARTS WITHOUT DUMPING CODES FIRST,
CAN GET VERY EXPENSIVE !!!

Here are my experiences with surging in my 90 V8.

Yes it does the stepped surging in increments of about
200-300rpm at a time.  Still does..... I'll explain later...

Note: First thing I did was to buy the sunpro multimeter that
       it pretty much a pre-requisite if you plan to fix your Audi :-)

Dumpcodes:

Grab a standard automotive single pole 12v light bulb (Like one of the
rear light bulbs or something similar) solder a wire to the side and
one to the bottom.  Or cobble something together like I did and
simply wrap the wire around it and tape :-)  Black plastic electrical
tape is acceptable here :-)

You know have a VAG 1551.... or close enough.. for today's lesson. :-)

Under the passenger side carpet are 4 jacks to stick the wires into

See previous post about making a test wire.....and how to dump codes...

Troubleshooting tips for surging:

Does it surge if you floor it ?

No, then gas is probably ok.

Yes, I would change gas stations.  Throw in a few applications of techron...

	Use 93 or better octane!!!

Does it surge in the first 20-30 seconds of running when stone cold ?

No,  The car runs in open loop or preset sensor signals for the first 20-30
      seconds.  No ECU involvement as far as automatic ignition timing
      changes and such.

      Possible problems:  O2 sensor, Hall Sender, ECU itself.

      The O2 sensor you can test with the multimeter from the harness
      on the drivers side, back of head connector.

Yes, Back to possible bad gas problem...

In my particular instance, I have a bad Hall Sender which required
replacing the complete distributor.  Big Cash for me, decided not
to do it yet.....  This was verified by the Dump Codes.

Of course when I did get the cash, it didn't make a difference... dddooohhh.

Tech Tip:

One thing I also did here was go to Radio Shack and buy a couple of
adjustable potentiometers in the 5-5000 ohm range.  I then would
preset them to an ohm level that a sensor should be feeding the
engine and plug into the wiring harness. Test drive to see if a
change has been affected.   I checked every sensor related to the
engine to confirm which sensor was hosed.

And yes there are quite a few of us V8 owners who peruse the list
on occasion :-)

Regards,

Mike LaRosa  (978) 442-1250

P.S. Just for fun,  Remove the Air Filter cover and go for a quick
      blast around the block.  Sounds like you could suck squirrels
      off the street into the intake from 10 feet away :-)

BBlake1055 at aol.com wrote:
> Are the O2 sensors the same on a 90' & a 92?  I was thinking about switching them before I go and make the purchase.  Is it pretty easy to change them?
> 
> Bob Blake
> 90' V8
> 91 V8
> 92 V8
> 
> 
> In a message dated 7/17/2004 8:30:08 PM Eastern Daylight Time, "S Dewitt" <sdewitt at stx.rr.com> writes:
> 
> 
>>It's your O2 sensor. Smae thing happened with my 91 5spd.... Replaced the 02
>>sensor and it went away.
>>
>>
>>Scott DeWitt
>>Advanced Automotion
>>817-939-6761
>>----- Original Message ----- 
>>From: <BBlake1055 at aol.com>
>>To: <v8 at audifans.com>
>>Sent: Saturday, July 17, 2004 7:19 PM
>>Subject: [V8] "Major Surging"
>>
>>
>>
>>>My 91' has recently developed some major surging problems.  It use to be
>>
>>minimal at 3/4 throttle but now it seems to be there 95% of the time.
>>
>>>I notice when the computer was in the "instant mileage" mode and I held it
>>
>>at a steady 65 mph the mileage would bounce back and forth from 28 mpg - to
>>21 mpg.  it feels as if the fuel pump is tuning on and off.  The overall gas
>>mileage is still ok.
>>
>>>Any ideas????
>>>
>>>Bob
>>>
>>>90 V8
>>>91 V8
>>>92 V8
>>>_______________________________________________
>>>Audifans V8 mailing list
>>>Send posts to: mailto:V8 at audifans.com
>>>Manage your list connection: http://www.audifans.com/mailman/listinfo/v8
>>>Have an Audi V8 question?  Check the Audifans Knowledgebase!
>>>http://www.audi-quattro.org/cgi-bin/twiki/view/Audi/V8
>>>Have a V8 answer? ... Please help others by adding to the KB ... all
>>
>>contributions welcome!
>>
>>
> 
> _______________________________________________
> Audifans V8 mailing list
> Send posts to: mailto:V8 at audifans.com
> Manage your list connection: http://www.audifans.com/mailman/listinfo/v8
> Have an Audi V8 question?  Check the Audifans Knowledgebase!
> http://www.audi-quattro.org/cgi-bin/twiki/view/Audi/V8
> Have a V8 answer? ... Please help others by adding to the KB ... all contributions welcome!

-- 

     _/_/_/  _/    _/  _/     _/      Mike LaRosa
    _/      _/    _/  _/_/   _/       TSE - HAS
   _/_/_/  _/    _/  _/  _/ _/        1617 Southwood Drive
      _/  _/    _/  _/   _/_/         Nashua, NH 03063
_/_/_/   _/_/_/   _/     _/
   S U N                              Phone: 781/442-1250
   S E R V I C E S                    Fax: 781/442-5488
                                      Email:mc.larosa at sun.com