[V8] V8 cutting out at about 1800 rpm

[cobram at juno.com]

I suspect you had a bad distributor, or sub component.  

When working, the hall sensor will supply the V8Q ECU with a signal at
startup that it uses as a base reference for the fuel injectors, once the
ECU adjusts, the TDC and Teeth senders take over as references for engine
management.  When there is no hall signal present, or the signal is out
of range (with the pin),  at startup the V8Q will default to a 16 degree
timing retard and ignore the knock sensors, then the TDC and Teeth
senders take over.  Running at 16 degree retard without knock sensors
will effect mileage and performance, but won't make her run on 4
cylinders.  I think the original poster was having a sudden cutout at
1800 RPM's, not a loss of power at 1800.

On the 5 cylinder engines with a hall sensor, if the reference pin and
hall window are out of range, or either signal is missing, the car will
not start at all.  This makes sense, because the ECU on a 5 cylinder
could be "fooled" into doing very bad things if it doesn't start with a
good reference of where #1 is.  Even on the 5 cylinder, once it starts,
you can disconnect the hall sensor and the car will run all day, since it
only uses the signal for starting, after that it's the reference pin.
This is for the "normal" ones, I don't know about the 20VT which is a
beast onto itself. 

I looked on one of the countless WP sites (zygmunt), looked up 1990 water
cooled VW bus, there is a Hall kit listed, I don't have a spare dizzy to
look at, but there is a good picture of the Vanagon kit, which looks like
you could get the Bosch number off it to see if it matches the V8Q.  The
kit is kind of expensive, what's a rebuilt dizzy going for these days?  I
recall the dealer distributors were around $280 brand new.

BCNU,
http://www.geocities.com/cobramsri/

 "Alan Kramer" <ackramer at hotmail.com> writes:
> You'd think it would throw hall sender codes, but it didn't in my 
> case.
> 
> Running on 4 cylinders only caused a "O2 sensor out of control range 
> - 
> intermittent" on VAG COM.  You could see the O2 sensor lean out on 
> the data 
> log as air passed through th 4 dead cylinders.
> 
> Alan