need help setting up Blaufergnugen 272 cam in 86 4000Q

[Huw Powell]

> I just installed the Blaufergnugen 272 cam in my 86 4000Q.   The car
> is stock, other than I removed the catalytic converter.
> 
> The car runs OK, but has two key problems.  When coming to a  stop,
> the idle hunts around, going from almost a stall (about 400 RPM) to
> over  1000, and oscillates.  Eventually it settles down, after about
> ten cycles  of this.

If "all else" is ok, this is often a symptom of the static mixture being 
set wrong.

> I've set the timing to about 15 degrees (versus the stock recommended
> 6 degrees).  Also, per the instructions from  Blau', I richened the
> idle mixture screw by about one turn.

If by idle mixture screw you mean the thing between the fuel lines and 
big air hose to the throttle body that takes a 3mm allen wrench, it must 
be adjusted in conjunction with measuring the control pressure actuator 
current, which should oscillate around 10 mA on your car.

There's a bunch of stuff about that somewhere on my website.

It is also fairly likely (although I have no direct experience with a 
272 cam on this system) that your idle conditions will not be "as good 
as stock" since the valve timing may not create the expected vacuum at 
low rpms to draw the right amount of fuel.

For fun you could try moderately radical ajustments of that 3 mm screw 
to see how it helps/hurts.  By the way, a whole turn is fairly radical. 
  Just keep track so you can return it to somewhere it runs if you go 
too far.

PS, richer is clockwise, backwards from a mixture screw on a 
carburettor, and will not actually "richen" the mixture (except at WOT), 
it just moves the baseline from which the OXS feedback loop adjusts the 
fueling.

hope this helps a bit

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/