XM V6 HELP

[davygr22]

I have just acquired a low mileage 2000 XM V6 3.0 with the ES9J4 24v engine - it drove perfectly on a 400mile trip home but has a problem when starting from cold: The symptoms are as follows : engine will rev up by itself to circa 1500/1750 rpm,return to idle,sometimes stutter & stall - it can stall when coming to a halt but can usually be restarted.This morning when it died at idle,it would not restart for about five minutes - once it has travelled about 1 mile there is no issue.
I have checked the electric fuel pump & it can be heard to run---- the vendor advised that the catalyst was renewed last year but wasn't sure about the lambda sensors - can these cause such issues from cold & how can they be tested(if at all)?

Thanks!!

[cc101]

Hi, not sure but you could try the TDC sensor normally located on the gearbox bell housing at the end of the engine. I'm not familiar with the v6 engines, but I've had those exact symptoms in another car and I changed the sensor, problem fixed. Other things could possibly be coolant temperature sensor, idle control valve, MAF/MAP sensor, possible vacuum leak.

Chris.

[Deanxm]

Reving up shortly before cutting out was always a sure fire sign of running out of fuel but it could be a knock sensor with a short or any of the sensors mentioned above, do you have an eml on?

D

[CitroJim]

It's unlikely to be the TDC sensor as these are normally very reliable and are anyway practically inaccessible on the V6.

Chris, you're on the money with the coolant temperature and MAP sensors. Both can cause this and the coolant temperature sensor is a known cause of trouble. A check with and ELIT or Lexia will soon confirm. They would be my favourite suspects along with a possible air leak on the inlet manifold. Ideally the manifold gasket should be replaced every time the manifold is lifted to change the rear bank spark plugs but often isn't.

The ECU will ignore the oxygen sensor when cold but again this can be checked with the ELIT or Lexia.

[davygr22]

Thanks guys - the EML light is not on - where are the coolant temp & MAF sensors located on this engine?I am reluctant to visit a Citroen Agent as they aren't great with older models - any members out there in Northern Ireland with a Lexia who could help?
Thanks Again,
David.

[CitroJim]

David,

The MAP sensor is on the back of the inlet manifold on the LH side as you look into the engine bay. It'll have a three-pin plug connected to it.

The Temperature Sensor is on the RH side of the engine screwed into the top of the alloy casting leading to the top hose union. It is the green sensor with I think a green plug on it. it may be hidden/obscured to a plastic cover on that side of the engine.

This picture sort of shows where it is and should give you a clue.....

[davygr22]

Thanks Jim,
II'll see how I get on with these - the parts are reasonably priced - temp sensor first as it is only about £7.....
PS I sent you am email about changing the trans fluid on the 4HP20 - need to know the proper procedure - are any special tools needed?

Thanks Again,
Davi.

[CitroJim]

PS I sent you am email about changing the trans fluid on the 4HP20 - need to know the proper procedure - are any special tools needed?

I'll be in touch about that David. I have the official procedures and some additional notes. There are two procedures depending on if your 'box has a dipstick or not.

[f00lzz]

http://www.frenchcarforum.co.uk/forum/v ... =3&t=35490" onclick="window.open(this.href);return false;

[CitroJim]

David, have you joined up on Club-XM yet?

You should, especially with your car

[CitroJim]

David, I've just sent you the oil change guide and additional notes on that subject via email. Please advise safe receipt...

[davygr22]

Thanks Jim,
Received the transmission oil change procedure - will order correct oil & attempt change in next few days!! Ordered temp sensor in attempt to cure cold start stuttering.....
Best Regards,
David.

[CitroJim]

Thanks Jim,
Received the transmission oil change procedure - will order correct oil & attempt change in next few days!! Ordered temp sensor in attempt to cure cold start stuttering.....
Best Regards,
David.

Excellent stuff David. Please let us know how it goes.

[davygr22]

Fitted new coolant temperature sensor - problem solved, I now have a beautifully smooth engine from cold start !! Surprised that this item can cause such dramatic symptoms.......
Thanks to all who pointed me in the correct direction.

David.

[cc101]

Great news, temp sensors on engines with ecu's play an important role (you wouldn't think they could cause much trouble!) but they tell the ecu how warm/cold the engine is and adjust fuel/air mix accordingly, when they're faulty they give all sorts of running issues, as you found out, but often overlooked as people think they just feed the temp gauge on the dash!

Nice cheap fix!

Chris