Hi,
Are there any electrical experts out there?
I have a 2.0 turbo XM,
the problem is, the engine wont start when it's hot.
Its ok starting from cold, and it runs ok. But if I turn it off and try to restart it, it starts and runs for a couple of seconds then dies.
after that it simply turns over but refuses to fire up.
If I leave it a few hours to cool down it starts ok.
The MOT is now due but I can't get it tested due to this problem, I don't really want to scrap it, so can anybody give any suggestions as to the cause please.
Thanks,
Paul.
Citroen Fuel injection/ignition problem
Moderator: RichardW
Difficult to be acurate without seeing the beast, I would suggest trying the cold start sensor, it could and has been known that this little sensor thinks that the car is allways cold, so it will start fine when cold but overfuel when hot. A bit like trying to start an old car with the choke out fully whilst it is hot.
I am sure that someone with a bit more knowledge will let you know where it is and if this can be checked by simply dissconecting it when hot??
Martin.
I am sure that someone with a bit more knowledge will let you know where it is and if this can be checked by simply dissconecting it when hot??
Martin.
Hi Paul -
Sounds like a typical temperature related sensor failure. The most likely candidate is then the TDC sensor as this provides timing reference for the ignition - and information on a turning engine - to the engine management ECU. No reference signal means no power to the fuel pump and no ignition.
A coldstart engine tempereture sensor will rarely if ever prevent a hot engine against starting. Instead it will give a lumpy (rich) idle.
Have you tried a steady bottom position of the acc pedal while cranking the engine ?
It is important not to "pump" the pedal
This would cancel the effect of a failing coldstart sensor.
The TDC sensor is located somewhere on the clutch bell housing pointing towards the flywheel. It is a dead simple wirewound magnetic coil sensor with a finite ohmic resistance of some 2-300 ohms.
You dont need to look for a specific ohmic reading however - as it will be disrupted to cause such fatal engine failure. Sometimes the cable/connector simply needs some TLC to make the engine run another 5yrs again.
Sounds like a typical temperature related sensor failure. The most likely candidate is then the TDC sensor as this provides timing reference for the ignition - and information on a turning engine - to the engine management ECU. No reference signal means no power to the fuel pump and no ignition.
A coldstart engine tempereture sensor will rarely if ever prevent a hot engine against starting. Instead it will give a lumpy (rich) idle.
Have you tried a steady bottom position of the acc pedal while cranking the engine ?
It is important not to "pump" the pedal
This would cancel the effect of a failing coldstart sensor.
The TDC sensor is located somewhere on the clutch bell housing pointing towards the flywheel. It is a dead simple wirewound magnetic coil sensor with a finite ohmic resistance of some 2-300 ohms.
You dont need to look for a specific ohmic reading however - as it will be disrupted to cause such fatal engine failure. Sometimes the cable/connector simply needs some TLC to make the engine run another 5yrs again.
Anders (DK) - '90 BX16Image
As a means to an end YOU CAN get the car MOT'd and then taxed keeping
it on the road rather than scrapping it so long as any potential overfueling
etc doesn't affect the emissions.
The tester can only examine what's offered in front of him on the day and
you are perfectly permitted to insist that the car is left running as there is
a hot starting issue - I have done a similar thing with an XM that had a
dodgy starter motor!!
There is no reason why the engine needs to be switched off for the test - in
fact one place I know keeps any Citroen running as they see the suspension
sinking as a hazard when the engine is off and they say it gets the car to
correct optimum operating temperature for the emissions test!!
Andrew
it on the road rather than scrapping it so long as any potential overfueling
etc doesn't affect the emissions.
The tester can only examine what's offered in front of him on the day and
you are perfectly permitted to insist that the car is left running as there is
a hot starting issue - I have done a similar thing with an XM that had a
dodgy starter motor!!
There is no reason why the engine needs to be switched off for the test - in
fact one place I know keeps any Citroen running as they see the suspension
sinking as a hazard when the engine is off and they say it gets the car to
correct optimum operating temperature for the emissions test!!
Andrew
Last edited by andmcit on 22 Jun 2008, 13:49, edited 1 time in total.
Another long shot - does the starter actually turn the engine over fast
enough when it's hot?
I've found the starter can get less effective when it does heat up and have
even had the magnets in the motor winding casing drop off the outer shell
eventually jamming the motor due to poor heat shielding on an Xm V6.
Just a few alternative thoughts!!
Andrew
enough when it's hot?
I've found the starter can get less effective when it does heat up and have
even had the magnets in the motor winding casing drop off the outer shell
eventually jamming the motor due to poor heat shielding on an Xm V6.
Just a few alternative thoughts!!
Andrew
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MikeT
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Why do you think it's electrical and what tests have you carried out so far?
If you suspect overfuelling, have you looked for evidence on spark plugs or from the exhaust? Have you even checked the air filter?
My only contribution to this guessing game is failing fuel pressure regulator or incorrect valve clearances or failing HT leads or coil.
If you suspect overfuelling, have you looked for evidence on spark plugs or from the exhaust? Have you even checked the air filter?
My only contribution to this guessing game is failing fuel pressure regulator or incorrect valve clearances or failing HT leads or coil.
Thanks for the replies everyone,
The biggest problem is that I don't know where all the sensors and relays are, or more to the point.......which ones.......the engine bay is full of them.
I'm waiting for a workshop manual on cd so hopefully I'll be able to identify the parts I'm looking for.
The first time it wouldn't start I called the AA. The AA man couldn't get a spark or any power at the injectors, he thought it was most likely the crank sensor, so I fitted a new one. It made no diference.
I've checked most of the connectors in the engine bay and they appear to be in very good condition, none of that green or white corrosion on them. I have very little understanding of auto electrics but I just have a feeling that it's an electrical component that has failed.......mainly because everyting is computerised.......... Could it be the ECU?
I thought that these days they could just hook it up to a computer and it told them what the problem was. But I can't find a mechanic who knows anything about XM's, not even Citroen specialists.
Andrew, I was told at the local MOT garage that they couldn't MOT it because of this problem, but from what you told me I think I'll try elsewhere. The MOT is my main concern at the moment.
Thanks again,
Paul.
The biggest problem is that I don't know where all the sensors and relays are, or more to the point.......which ones.......the engine bay is full of them.
I'm waiting for a workshop manual on cd so hopefully I'll be able to identify the parts I'm looking for.
The first time it wouldn't start I called the AA. The AA man couldn't get a spark or any power at the injectors, he thought it was most likely the crank sensor, so I fitted a new one. It made no diference.
I've checked most of the connectors in the engine bay and they appear to be in very good condition, none of that green or white corrosion on them. I have very little understanding of auto electrics but I just have a feeling that it's an electrical component that has failed.......mainly because everyting is computerised.......... Could it be the ECU?
I thought that these days they could just hook it up to a computer and it told them what the problem was. But I can't find a mechanic who knows anything about XM's, not even Citroen specialists.
Andrew, I was told at the local MOT garage that they couldn't MOT it because of this problem, but from what you told me I think I'll try elsewhere. The MOT is my main concern at the moment.
Thanks again,
Paul.
At the end of the day, anything that is carried out on the MOT is going
to be at the discretion of the professional individual tester and interestingly
over the years I've found differences with them which are probably down to
a whole series of factors such as interpretation, experience and subjectivity.
A practical option would be to speak to different testers for their
professional opinion. At the end of the day the car isn't unsafe/dangerous
and the poor hot starting is simply your personal inconvenience.
I believe there is such a forum for MOT discussion as well as VOSA's
own website as alternative sources to determine where you stand.
There is the final more practical option of leaving the car before a test
appointment in such a manner that the car is stone cold when it is due
to be tested as it runs well before getting fully warmed up!!
Andrew
to be at the discretion of the professional individual tester and interestingly
over the years I've found differences with them which are probably down to
a whole series of factors such as interpretation, experience and subjectivity.
A practical option would be to speak to different testers for their
professional opinion. At the end of the day the car isn't unsafe/dangerous
and the poor hot starting is simply your personal inconvenience.
I believe there is such a forum for MOT discussion as well as VOSA's
own website as alternative sources to determine where you stand.
There is the final more practical option of leaving the car before a test
appointment in such a manner that the car is stone cold when it is due
to be tested as it runs well before getting fully warmed up!!
Andrew