V6 no start update - it starts

[Tyson Varosyan]

I am familiar with newer engines. Not Audi per say, but still an EFI ODB1&2
motors which are, in principal, all the same. To my knowledge, O2's have
absolutely nothing to do with the car starting. They trim fuel levels for
optimal burn once the car is warmed up. No O2 sensor I have ever heard of
will even give a reading until the car has ran for a few minutes. They must
be hot and even those with electrical heaters, like the ones on my 3000GT,
take about 3-4 minutes to start working. Even at maximum trim to ether raise
or lower the mixture, they should not come anywhere close to preventing a
car from starting or idling. I'm sorry man, but I am going to have to second
others on this list in saying that you have not found your problem.

Things to check:

Compression: First and foremost ether do it yourself or have the mechanic do
it. Not sure what the numbers should be on your car, but if you get over
90PSI (most cars with 10:1 compression ratio should get in the 150psi range)
and have all your cylinders +/- 10PSI of one another, you can check that off
as "OK to start"

Ignition: Pull one of the plug wires (leave the plug in the motor). Hold the
wire about 6" away from the tip and place the tip about 1" away from the
engine's valve cover or any other metal part. Have someone crank the car and
watch for a spark to jump your 1" gap. If that test works for all 6
cylinders, repeat with one of the plugs. Put a towel over the spark plug
hole as gasoline mist may shoot out. Place the plug in the wire and hold the
bottom end of the plug against any metal part of the car. Have someone crank
and watch for a spark to jump across. If that works, check off Ignition as
"OK to start"

Fuel: When doing the ignition test, sniff inside the spark plug hole for
gasoline smell. If the car is not starting, your plugs should come out with
a few droplets of gasoline on them. If this proves true, mark fuel as "OK to
start" (Note: You may also spray some starting fluid into the engine (take
apart the air filter box and spray the fluid into the tube going to the
engine) to see if it will start on the starting fluid. If it does, fuel
supply (due ether to the ECU, MAS, Injectors, Fuel Pump, etc) is not there
in the proper quantity.)

Air: Well, obviously verify that your butterfly valve (the thing your gas
pedal cable goes to and the thing that moves around under the hood when you
push the pedal) is working. Take the big hose off and look at the valve
while someone is pushing the pedal. The Air sensor (MAS?) is also important.
It is the boxy thing that is somewhere between your air filter and your
butterfly valve. It will have a big electrical plug on it. Make sure that
the plug is clean and connected. If this proves true, mark air as "OK to
start"

Timing: This is the least important as even timing greatly messed up will
let your car start and run. However, to check it, you will need a timing
light. Follow manual instructions for your particular car. The car has to be
running to be properly tuned, but you can still do the test while cranking
to ensure that the ignition timing is in the right ballpark. This will
verify your ignition timing. Valve timing should be OK unless you have ether
0 compression (see above) or hear loud knocking from the engine when it is
being turned over.

Compression, Ignition, Gasoline, Air and Timing are that are required to
have a running car. Getting it to run well is the job of the ECU, O2, EGR,
MAS and all the other electronic rubbish.

Good luck.

Tyson Varosyan
Technical Manager, Uptime Technical Solutions LLC.
tyson at up-times.com
www.up-times.com
206-715-TECH (8324)

UpTime/OnTime/AnyTime

-----Original Message-----
From: quattro-bounces at audifans.com
[mailto:quattro-bounces at audifans.com]On Behalf Of Huw Powell
Sent: Tuesday, February 08, 2005 7:34 PM
To: Kent McLean
Cc: V6-12V list; quattro-list
Subject: Re: V6 no start update - it starts


> Yesterday I had the car towed to the mechanic. Before we put
> it on the flat bed, I tried one more time -- half a cough, but
> still no-start.  Today the mechanic looked at it. Whenever he
> gets a non-starting car in, he automatically replaces the plugs.
> Which I had just done on Sunday (0 miles on the plugs, since
> the car wouldn't start for me). He got in the car, pumped it
> hard, and -- the M.F. started!!!
>
> He let it run, shut it down, started it right back up. The third
> time, letting it idle, it stalled. Hooray! Pulling the real codes
> with a Vag-Com (not the blink codes with the CEL), it showed two
> bad O2 sensors.  I'll replace them tomorrow.

How could bad O2 sensors prevent a car from starting?  The ancient Audis
I am familiar with don't even "listen" to the OXS until it has a little
time to warm up.

> The mechanic didn't do anything I didn't do. Well, except for
> pumping the gas hard (I just pumped it). It started for him, but
> not for me.  Go figure.
>
> So, what did we learn?

I don't think you learned anything yet about what's wrong - although, I
may be wrong, right?  Let us know how it goes with new OXS's in there!

--
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/
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