Hi, this is the first time I've used this forum, but from what I've seem already I'll be surprised if someone hasn't got the answer to my problem..........!
I have a '98 Xantia 1.8 16v, which generally runs very well but has an intermittent problem where it will suddenly lose all power for a few seconds and then pick up again. Almost as if the ignition or the fuel supply has been cut.
The car will idle fine (since I replaced the idle stepper motor!). The frustrating thing is that this problem may occur only once in a week and then 10 times in ten minutes!!
From other posts I have read, is it possible that the throttle potentiometer is faulty?
Any help will be much appreciated!
Xantia power loss
Moderator: RichardW
Hi MrGibbs -
I doubt a trouble potientiometer by this symptom.
The reason is that your acc foot will allways override any lower position on the throttle flap. But then again - a missing poti will indeed signal wrongly to the ECU - posibly thinking the throttle flap is closed momentary - then turning down fuel supply to injectors. But that would most likely occur at the same single point on acc travel.
Should be possible to diagnose by slooowly bottoming the acc while engine is struggling a bit in hi gear.
The most common symptom on a trouble poti is the scaring ghosting around on idle rev's - at times reaching up to insane rev levels.
I'd first go for more simple service issues - like a failing plug/HT cable - even a loose fit HT cable on one of the plugs.
A clogged fuel filter is a sure trouble maker - just like any water in the tank.
The ignition TDC sensor should be suspected for corroded connector contact pins. Same goes for injector connectors - even the injector & fuel pump relay.
Note that your symptom could in fact be caused by the opposite of your suggestion : momentary overrich mixture. This could be caused by the engine temp sensor on it's way out - or once again - corroded contact pins on it's connector.
Any black/grey exhaust clouds coinciding with the symptom ?
I doubt a trouble potientiometer by this symptom.
The reason is that your acc foot will allways override any lower position on the throttle flap. But then again - a missing poti will indeed signal wrongly to the ECU - posibly thinking the throttle flap is closed momentary - then turning down fuel supply to injectors. But that would most likely occur at the same single point on acc travel.
Should be possible to diagnose by slooowly bottoming the acc while engine is struggling a bit in hi gear.
The most common symptom on a trouble poti is the scaring ghosting around on idle rev's - at times reaching up to insane rev levels.
I'd first go for more simple service issues - like a failing plug/HT cable - even a loose fit HT cable on one of the plugs.
A clogged fuel filter is a sure trouble maker - just like any water in the tank.
The ignition TDC sensor should be suspected for corroded connector contact pins. Same goes for injector connectors - even the injector & fuel pump relay.
Note that your symptom could in fact be caused by the opposite of your suggestion : momentary overrich mixture. This could be caused by the engine temp sensor on it's way out - or once again - corroded contact pins on it's connector.
Any black/grey exhaust clouds coinciding with the symptom ?
Thanks for the replies guys - I'm feeling a bit more confident in my own trouble shooting abilities already! Here's a bit more info. for you....
I've already replaced the fuel filter and plugs have been replaced recently as part of a regular service. Also, I don't think I have HT leads etc. as the 16v engine has individual coils for each plug integrated into the cover on top of the engine(I could be wrong there though!)
TDC sensor sounds interesting though - where is this located?
I've already replaced the fuel filter and plugs have been replaced recently as part of a regular service. Also, I don't think I have HT leads etc. as the 16v engine has individual coils for each plug integrated into the cover on top of the engine(I could be wrong there though!)
TDC sensor sounds interesting though - where is this located?
Allright -
Assuming you don't hold back any more secrets [}:)]
These single coils (if fitted) are renown for their lack of reliability.
Due to their construction - it should be possible to provoke any intermittent problem by patiently heating one at a time with a hair dryer during engine idle. Note it takes time for the heat to propagate trough the coil entirely. Don't be tempted to melt down the surface. You may try your luck.
The TDC sensor is fitted at some obvious point to read off the toothing on the flywheel. It's got a 2pole connector piece.
Assuming you don't hold back any more secrets [}:)]
These single coils (if fitted) are renown for their lack of reliability.
Due to their construction - it should be possible to provoke any intermittent problem by patiently heating one at a time with a hair dryer during engine idle. Note it takes time for the heat to propagate trough the coil entirely. Don't be tempted to melt down the surface. You may try your luck.
The TDC sensor is fitted at some obvious point to read off the toothing on the flywheel. It's got a 2pole connector piece.