Xantia 1.8 16v 'Missing' Problem sorted, Thanks

Hugo · Post by **Hugo** » 07 Oct 2003, 05:37

Hi
The car is missing during normal running and doesn't run that well when revved up high. This fault cannot be atributed to one cylinder alone.
Between a couple of guys and I we have tried to disconnect all injectors, unblocked a breather pipe or two, I even had a garage look at it for a few hours - all to no avail. The garage did not charge me, well a pint or two is owed.
We even tried changing the coil pack, checked exhaust seal in front of the labda sensor, listened for leaks in the air intake etc etc etc
The ECU light is not coming on, so what could the problem be?
Where is the MAP sensor, and how would you remove and inspect and test this?
How do you remove the lamda sensor in the front pipe? There seems to be a 21mm hexagon head here but I don't know whether or not I am supposed to pull the sensor out or unscrew it.
Please help - deparate!!!
Thanks
Hugo

AndersDK · Post by **AndersDK** » 07 Oct 2003, 06:36

I think you should leave the Lambda sonde where it is.
The indications are intermitting misfires on random cylinders any speed.
This can not be caused by failing sensors controlling the mixture - as you would then have constant indications of lean or rich running.
I'd look for either water in the fuel - or an intermittent working ignition TDC sensor or it's cabling/connector.

Hugo · Post by **Hugo** » 07 Oct 2003, 21:46

Hi Anders
Thanks for your reply. Hands are nor firmly OFF the Lambda Sensor!
Could you please tell me where the TDC Sensor is.
I have run about 10 litres of fuel since this problem started, all freshly bought from a petrol station and served up in those plastic petrol cans.
Many thanks
Hugo

AndersDK · Post by **AndersDK** » 07 Oct 2003, 23:08

The TDC sensor is a magnetic coil (hall) sensor located somewhere on the perimeter of the flywheel (clutch) housing.
It can be tested by measuring coil windings ohmic resistance - should be in the vicinity of 100 ohms - any temperature.

Hugo · Post by **Hugo** » 08 Oct 2003, 00:32

Anders
Thanks,
Whilst re reading your last post I remembered I am getting rich running as well.
Hugo

AndersDK · Post by **AndersDK** » 08 Oct 2003, 03:29

Ok Hugo -
The rich running could very well be the effect of missing ignition.
To prevent confusing matters - I think you should follow this first track from the indication of random missing any speed - i.e. check out the ignition TDC sensor.
Then we take it from there.

Hugo · Post by **Hugo** » 16 Oct 2003, 01:41

Hi Anders
Just to let you know, I haven't done any more work to that car since reading your last post. But I am grateful for your help.
Thanks a lot
Hugo

Hugo · Post by **Hugo** » 16 Oct 2003, 21:35

Hi Anders
Since my last post yesterday, I think I have found the TDC Sensor, The engine stopped when I disconnected it.
There are 3 spades on the connecter on the end of the wire coming out from the flywheel vacinity. A reading across the centre and one of the side spades came up at around 99 to 102 ohms, so it looks like this is not where the problem is.
In addition, the fact that the engine stopped when it was disconnected demonstrated that it was doing something at least.
Also, I forgot to mention that in addition to the missing, the car is also backfiring especially when starting up.
In addition, disconnecting the Lamda Sensor does nothing to affect its running.
Any further guidence would be much appreciated.
Many thanks
Hugo

Hugo · Post by **Hugo** » 17 Oct 2003, 23:29

Leading on from my last post here, does anyone know the required Readings/resistances of the other sensors here so I can work through them?
Any advice much appreciated.
Hugo

AndersDK · Post by **AndersDK** » 18 Oct 2003, 00:29

hugo -
The backfiring may indicate an ignition problem - then likely to be an unstable TDC ignition sensor. They are known to fail even if they check out ok with an ohm meter.
Try this site for further info on components involved with the engine management system :
http://www.tramontana.co.hu/citroen/

Hugo · Post by **Hugo** » 18 Oct 2003, 00:34

Thanks Anders
I'll check out that site and let you know how I get on!
Thanks again
Hugo

Hugo · Post by **Hugo** » 18 Oct 2003, 00:40

I may also have another sensor from the old engine that came out of the car. I may try swapping them around.
Hugo

CITMAN · Post by **CITMAN** » 18 Oct 2003, 00:48

If I were you I would get the car down the citroen garage for diagnostic before your cat dies on you. They dont like it when the engines misfires it cause them overheat. £200 for a cat is not cheap whereas diagnostic at cit specialist would be much much cheaper than that. Don't forgot to change your spark plugs as well when the engine is running okay again. MAP sensor my main suspect thats if it has one.

Jaxs · Post by **Jaxs** » 18 Oct 2003, 02:16

Try and avoid disconnecting Engine management components as a form of testing,. This generates a fault code in the ECU and can contribute to poor engine performance.
Have you carried out a compression test? The back fire, mis fire could all be attibuted to either sticky valves, poor compression, etc.
Would suggest compression and /or cylinder leakage test.

Hugo · Post by **Hugo** » 18 Oct 2003, 13:56

Thanks for your input guys.
Citman
I would very much like to get the car to the Citroen Specialist for a diagnostic check but it is neither insured nor taxed. Hence I am looking at £100 before it even leaves my drive! I was going to use it myself but have now got another car.
Does anyone know of a website that can direct me through a self diagnostic test? I know vauxalls can be tested this way and fault codes read by counting flashes on the ECU light etc.
Jaxs
Thanks for your ideas, however, the engine is a low mileage C18000 replacement, I suspect that these faults are unlikely.
In addition it was running fine then suddenly deteriorated instantly, rather than over time.
Thanks again
Hugo