[Diy_efi] Audi idle issue

Tue Feb 28 01:48:02 UTC 2006

Was Audi still using K-jet in 89?  I thought Ferrari was the last
manufacturer to use that mechanical injection stuff!

One thing that messed me up setting CO with the 308's K-jet the first time,
you have to remove the allen wrench and plug the hole then wait a couple of
seconds before you can get a good reading,  otherwise you have an air leak.
At first it seemed like the changes were not having any effect,  but once I
started plugging the hole after each adjustment I could just dial it in
perfectly.  Where are you Ernest?  My 4 gas analyzer would help if you're
near CT.

Bill

> From: "David Allen" <davida1 at hiwaay.net>
> Reply-To: diy_efi at diy-efi.org
> Date: Mon, 27 Feb 2006 19:03:48 -0800
> To: <diy_efi at diy-efi.org>
> Subject: Re: [Diy_efi] Audi idle issue
> 
> The K-jet "toilet bowl" has a tapered housing below the plate.  The more air
> the engine draws in, the farther down in this tapered housing the plate will
> move.  The fuel distributor increases fuel flow as the plate draws down.  If
> you make the plate sit higher in the toilet bowl with the engine off, it
> will press the fuel distributor in further (more fuel) when the plate is
> drawn down by a given airflow.  That adjustment adjusts the linkage between
> the plate and the valving in the fuel distributor.
> Ok- this should ballpark adjust it. It has been a long time and many many
> miles since I did this so you may have to work out some details. Before
> anyone flames me please re-read this statement! :-)
> If the engine runs only when the cold start valve is open, it is probably
> running too lean to run without this extra fuel.
> Since the idle mix adjustment is already off-base, set it to an
> intermediate position for a starting point.
> Unplug the O2 sensor. This should make the system default to a "neutral"
> feedback trim on the mixture control solenoid. (someone correct me if I am
> wrong on this - it's been a while)
> Start by manually pressing the airflow meter flap down (in the same
> diretion that airflow draws it when the engine runs).  Press it down and
> find a position where you can hold it by hand to make the engine idle. (have
> an assistant or use a remote starter button)  If you can make it idle by
> pressing the plate down, then you know that an adjustment here will correct
> the problem.
> Mark a line on the inside of the "toilet bowl" housing at the edge of the
> plate with the engine off and the plate fully up.  Adjust the screw and
> release the plate.  Continue adjusting until the plate now rests just above
> the line (line hidden below plate) with the plate fully up and engine off.
> See if idling is possible without pressing on the plate. Repeat small
> adjustments until engine idles.
> Once you have it idling okay, test drive it.  Look for signs of obvious
> lean running such as hesitation or pinging.  If it does seem lean, move the
> adjustment to raise the airflow plate higher up in the housing (draw another
> line and cover it up). Repeat until you have the engine running OK when it
> is above idle, then use the idle adjustment mixture screw to dial in the
> idle.
> Moving the airflow flap afects AFR across the whole range including idle
> therefore this has to be adjusted before adjusting the idle.
> Another point to ponder - on some K-Jet systems (not sure about yours) the
> AFM flap has to be drawn down some to actuate the fuel pump relay.  If the
> adjustment of the plate is SO far off maybe the arm doesn't move down far
> enough to actuate the fuelpump relay?
> Most of the systems I worked on were on BMW, Mercedes and Saab so there
> may be details that differ on this car.
> Good luck!
> David
> 
> 
> ----- Original Message -----
> From: "Ernest Buckler" <ebuckler at icehouse.net>
> To: <diy_efi at diy-efi.org>
> Sent: Monday, February 27, 2006 4:02 PM
> Subject: Re: [Diy_efi] Audi idle issue
> 
> 
>>> Using a helper to press down the airflow meter flap to keep the engine
>>> idling, fog each area listening for the engine speed to increase.
>> 
>>> Why did you need to adjust the CO adjustment?
>> 
>> David,
>> Thanks for the extensive advice, will double check all those areas - I
> have
>> a new boot (old one was cracked, as you mention - but the car still
> ran...),
>> new hoses, new clamps, clean ISW, new thermoswiitch, new ign. wires, new
>> dist. inner parts.   The car ran fine once warm but very rich at idle
> (black
>> smoke, etc) so I was trying to adjust mix with the only means I knew (idle
>> screw did nothing, even after total bench cleaning of throttle plate,
>> resoldering of bad joints inside that switch) - which was the air flap (CO
>> adjustment, therefore the overall "jetting" (mixture) adjustment,
> according
>> to my thinking??   In frustration, I turned it a LOT, trying to get
>> something to change that rich idle.  Nada.  But - my Duh here - then I
>> discovered that the throttle switch plug was not in tight, had fallen out.
>> Now it's plugged back in, BUT the engine won't run after cold start shuts
>> off.  No more black smoke - no smoke at all...  And I have been told that
>> the air flap screw is normally adjusted in tiny fractions of a turn -
>> whereas I could be 3 or 4 or 5 turns out, no way of knowing what I did in
> my
>> frustration (above).   To much random action, not enough thinking things
>> thru on my part.  The Bentley manual gives a method for getting the basic
>> air flap setting, but it requires removing the air boot, and that was such
> a
>> PITA to install, I'm hoping there's a "tune by ear method" that'll get me
>> close enough to drive the car to an emissions shop for final tweaking.
>> Thanks for any clues,
>> Ernest B.
>> 
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