Re: 4KQ OXS & rev limiter ?

[Huw Powell <human@nh.ultranet.com>]

> New, heated OXY made no difference.   :(    Recent advice is to try
> diddling the mixture screw in the metering unit. The larger engine, higher
> compression, ported IM, head and EM combined with a very radical
> long-duration and high-lift cam may have the calibration o for out that it
> i not possible to detect via the O2 meter that the system might in fact be
> in closed-loop. but cannot get any real action due to being sos far out on
> the rich side.

Now that I just got my copy of the Bosch fuel injection book and I know
so much more :-)...

You measure the current going to the pressure regulator (front of the
fuel metering block) to "dial in" the static mixture.  This is also one
place to determine if the system is in closed loop.  The idle setting is
supposed to be 10 mA but it will fluctuate from about 8 to 12 mA - the
fluctuaction indicates closed loop.  As would a varying OXS ouput
voltage.

> 
> What size hex is needed to adjust the mixture? I hear 3mm, but it does not
> 'feel' like it is engaging the adjuster. 2.5MM mebbe?

it is definitely 3mm but it could be dirty.  try shooting it with some
brake cleaner or something to clean the little hex socket out.

> > I need to get like 300-500 more RPM before the rev-limiter stops the fun.
> > Any easy ways to do this? Is this controlled by the fool-pump relay?
> Could
> > the relay be modified to increase the rev limit?
> afaik it's the fuel pump relay counting the coil signal. 

That was me being wrong there folks.  I now know... on the CIS-E cars
the rev limiting function is carried out by the fuel ecu, and what it
does is send a -40 mA (?) signal to the pressure regulator to cut the
fuel supply to the injectors.  Fuel pump supposedly stays on.  remember,
this is "book larnin'", so take it with a grain of salt.  How would you
raise this limit?  since the hall signal from the distributor is going
to the fuel ecu and the igntion control unit together, you couldn;t mess
with this too much... but maybe they split up in a way that you could
insert a "divide by" device in the wire to the fuel ecu, making it think
the rpms are lower.  Don;t know if this would work, etc.

hope this helps a little...




-- 
Huw Powell

http://www.thebook.com/human-speakers

82 Audi Coupe; 84 4kq; 85 Coupe GT
http://www.nh.ultranet.com/~human