CITROEN CX 2000 Repair Manual page 95

CHECKING THE DEVICE FOR OPENING THE
BUTTERFLY
1. Electrical components :
With the engine at
idling
spu~d. disconnect one
of the leads to the C< PIERBURG ,) electro-valve (1).
the engine speed must increase.
If not. using a test lamp, check the following
that.
under deceleration
and for any engine
speed
Nd
> 1800 ? 100 rpm the /C PIERBURG >l
electro-valve (1 ) is not energized.
- that.
under acceleration
and for any engine
speed from idling speed to the speed
Nc = Nd + 50 to 250 rpm. the C< PIERBURG ,,
electro-valve is energized.
If in this case the electro-valve is not energized.
ensure ( using a test lamp ) that the winding in
relay ( 2) is not enerqized for an engine speed
below "
Nd
" ( under deceleration ) or an engine
speed below "
NC
" ( under acceleration ).
Accelerate the engine up to engine speed " NC n :
- the winding in relay (2 ) must be enerqized.
If not. replace the electronic unit (3) after
having checked the connections.
2. Pneumatic components :
Ensure that the vacuum reaches capsule ( 4 1 ( device
for opening butterfly ) when the engine speed is
equal or above "
NC
".
Make sure the vacuum exists at the carburettor
outlet. If it does. and yet does not reach cap-
sule (4) ( device for opening butterfly 1. check
the circuit along all its length. plugging it first
level with the 3-way union. on the air-supply
valve side.