My 1992 BX turbo diesel has a very lumpy tickover.
It runs very well whilst driving.
Is there an ajustment on the roto pump just for tickover to weaken the mixture as in a petrol engine?
Bernie
Lumpy tickover
Moderator: RichardW
There is no "choke" on a diesel for idle mix.
Instead you have the coldstart device which slightly offsets the injection timing at cold idle. This is the rather clumpsy cylindric device in thermostat housing with a bowden cable connecting to the roto pump.
With cold engine this cable attachment is adjusted against endstop. You can then mark up (white paint) the inner cable exactly where it protrudes - to check it moves out at warm engine - thus moving/releasing the lever it attaches to.
The ferrule is used for fine adjusting the tension on cable at cold.
If it does not move (some 6mm) - the device needs replacement - a common wear problem.
Instead you have the coldstart device which slightly offsets the injection timing at cold idle. This is the rather clumpsy cylindric device in thermostat housing with a bowden cable connecting to the roto pump.
With cold engine this cable attachment is adjusted against endstop. You can then mark up (white paint) the inner cable exactly where it protrudes - to check it moves out at warm engine - thus moving/releasing the lever it attaches to.
The ferrule is used for fine adjusting the tension on cable at cold.
If it does not move (some 6mm) - the device needs replacement - a common wear problem.
The principal of the diesel engine is that fuel burns in excess air - which means that the power output of the engine (and hence its speed) is simply controlled by the amount of fuel injected - so there is no throttle valve as found in a petrol engine and no mixture to adjust.
On the assumption that the engine is not idling too slowly and is otherwise healthy and not smoking excessively I wonder if you have an air leak in the fuel system.
Jeremy
On the assumption that the engine is not idling too slowly and is otherwise healthy and not smoking excessively I wonder if you have an air leak in the fuel system.
Jeremy
Does the BX have the newer or older fuel supply + filter setup?
Older = push-button filter on l/h side
Newer = Priming bulb on l/h side, filter on top of thermostat housing
I've had problems with the newer setup - leaking filter + occasional fuel starvation as a result. Also - are the metal fuel lines under
the car in good order? These tend to corrode and can let in air.
Older = push-button filter on l/h side
Newer = Priming bulb on l/h side, filter on top of thermostat housing
I've had problems with the newer setup - leaking filter + occasional fuel starvation as a result. Also - are the metal fuel lines under
the car in good order? These tend to corrode and can let in air.
Bernie -
The coldstart cable MUST be adjusted when cold - such the cable is exactly tight. Otherwise the hot idle timing is wrong.
Another common problem is simply too slow hot idle - which is adjusted on the throttle end stop.
Hot idle to be 750-800rpm
Cold idle to be 900-1000rpm
- for both n/a & turbo.
Donno if your '92 engine still has the old generation Citroen diagnostic test connector - with a TDC magnetic sensor at flywheel.
If this is fitted - you can tap the rpm from this sensor.
The coldstart cable MUST be adjusted when cold - such the cable is exactly tight. Otherwise the hot idle timing is wrong.
Another common problem is simply too slow hot idle - which is adjusted on the throttle end stop.
Hot idle to be 750-800rpm
Cold idle to be 900-1000rpm
- for both n/a & turbo.
Donno if your '92 engine still has the old generation Citroen diagnostic test connector - with a TDC magnetic sensor at flywheel.
If this is fitted - you can tap the rpm from this sensor.
Thanks for your replies.
If there was an air leak and I presume air bubbles in the fuel would it cause the lumpy tickover?
When I say lumpy, it ticks over very steady and rythmicly but laboured as if over rich and shakes the car. The engine mounts are good.
At present I have adjusted the cold start with plenty of slack when hot so it is not interferring with the hot running.
I have the tickover at approx 850 rpm.
As I said before the engine preforms well above tickover, very smooth and quiet.
If there was an air leak and I presume air bubbles in the fuel would it cause the lumpy tickover?
When I say lumpy, it ticks over very steady and rythmicly but laboured as if over rich and shakes the car. The engine mounts are good.
At present I have adjusted the cold start with plenty of slack when hot so it is not interferring with the hot running.
I have the tickover at approx 850 rpm.
As I said before the engine preforms well above tickover, very smooth and quiet.
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