re. 5ktq emissions woes

[Ben Swann]

To: quattro at audifans.com
Cc:
Subject: 5ktq emissions woes
From: qshipaz at juno.com

Greetings,

The hangar queen ventured out of the hangar these past two days, boldened
b=
y the temporary tags, hoping to get legal.

-- I thought I's throw in my comments since I saw no one else replies as of
yet.

Patient is an 86 5ktq. Hasn't been registered since 12/99 in California,
wh=
en it passed Cal emissions easily. I admit I have not done all the
requisit=
e filters yet, although the LOF has just been done. 94K on the (working)
od=
ometer. In AZ, a Quattro doesn't have to pass anything but the idle test
(h=
ow would you dyno one??) and the equipment check (which it passed- car is
b=
one stock, so far)
Idle readings were 363 ppm HC and 7.45% CO! Standards are 220 and 1.20%.

-- Well it is running rich.

Clearly something is amiss. Fuel is mostly Chevron premium (but I can't
vou=
ch for the age of what was in the tank before- probably no more than a 1/4
=
tank. And the car was driven around the neighborhood fairly frequently by
t=
he MBZ/VW shop owner who previously was the TQ's custodian. Could this be
e=
ntirely due to the fuel?

-- not likely

Thinking of Phil: "Don't guess. Pull the codes." I did. Tried twice, and
ge=
t 4444, as well as a smooth idle at 900 rpm, only about 1.1 bar boost
thoug=
h=2E I attribute this to the fuel quality waking up the knock sensor. O2
se=
nsor is my next guess- but wouldn't the code come up if that were the case?

-- No, the Oxy sensor does not provide any feedback to check itself, nor
does the system have capability to determine it is giving a false reading.

I am aware that there are many possible factors here. IME, messing with
the=
 CIS mixture screw only produces a foul-running car if you do not have a
"s=
niffer" to check the emissions while you do so. So what am I missing? I
cou=
ld just bring it to the shop, but I've gotten away from that for every bit
=
of mech. work I've done on the Q or the Z-car in te last two years. Surely
=
I can figure this out- idle testing only can't be that hard a goal to
shoot=
 for. Any BTDTs will be much appreciated.

-- You most likely have a vacuem leak, perhaps among other things.

Last thing- there is a crack in the downpipe, behind the turbo, at the
fact=
ory weld. I realize this is serious, and will be replacing it very soon,
bu=
t I don't think this negatively affects idle emissions- or does it?

-- Yes it can, but what I found after doing mine is that the hairline
fractures were not affecting performance or emmisions as much as I had
thought.  The addition of air or leaking out of exhaust can throw off O2
sense readings a little, particularly at idle.  A serious leak, that is one
you can hear and smell will definately throw off the mixture and cause
driveability problems as well.

Before everyone jumps at me for not methodically giving it a full tune-up,
=
T-belt, all fluids- think of this. I have driven the car approx. 20 miles
b=
efore today. I have a bit of a philosophical problem with pouring hundreds
=
of $ into a vehicle which currently has only a temp. tag and an open out
of=
 state title. I can't get title or registration until I slay this
emissions=
 dragon. Just a thought.

-- Tuneup is always good, as it provides a baseline and tends to help rule
those  things out when troubleshooting.

Quattro Kool-aid: I had fun on the freeway today. Haven't run a turbo 44
on=
 the highway in three years! The corkscrew ramps at double the posted 25
we=
re great. This is my first Quattro though I've had two other Audis- well
wo=
rth it. But you guys knew that already... BTW no driveline vibes and the
di=
ff locks work. At 94K, this is a low-mileage 5ktq!

-- Yes, but enough age and mileage to assure the vacuem line you replace
will fall apart as you remove them.

Regards,
Rob

-- Hope this helps.

-- Ben