Xantia - Bad smell from the exhaust system

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Re: Re:

Post by CitroJim »

DickieG wrote:
lancia58 wrote:I found this link it sais the frequency is 1 Hz, the Lexia sample rate is too low to see if it changes at a rate if 1Hz, the only possibility is sign an oscilloscope
Lexia has an oscilloscope built in which you can access via the diagnostics menu.
Only a real Lexia sadly Richard. Although the PC-based Chixias have the option I believe you need another interface to make the oscilloscope work.

Generally the response of the O2 sensor can be interpreted on a Lexia by watching how the value changes. It should be constantly changing and cycling between 200 and 800 mV roughly over the course of a second or so. If it's static or doesn't reach the highs and lows then it's not a happy bunny.

A good digital multimeter can read the O2 sensor output directly and if you can get one with a quasi-analog bargraph display then even better as you can reallay watch it swinging nicely then. Never use an old-fashioned analogue voltmeter as there internal resistance is too low and it will excessively load the O2 sensor and give erroneous readings. Likewise never try to test an O2 sensor with an ohmmeter of any sort. It will damage the O2 sensor.


Zohar, Lambda of 1.01 is in limits (UK MOT between 0.970 and 1.030) CO at 0.09 is fine and a pass. I'd say all was working well. Do you have the HC (unburned hydrocarbons) reading too?
Jim

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Re: Xantia - Bad smell from the exhaust system

Post by lancia58 »

The HC is 153

Zohar
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Re:

Post by Deanxm »

lancia58 wrote:Hi

It passed the MOT test on January and it was on the edge , the guy told me that I’ll better change it because it is on the edge. The thing is that the fuel consumption at freeway driving is excellent. This is why I ‘am confused . I test with the Lexia you can see the test result in a previous post of this topic

Thanks
Zohar

I wouldnt say your economy is exellent myself, my 2.0 8v Auto XM will not do below 20mpg round town and depending on cruising speed will do between 32 and 40mpg on the motorway, surely a 16v xant with a smart auto should be at least matching the xm?
The black staining on the bumper suggests there is a rich mixture or oil burning too.

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Re: Xantia - Bad smell from the exhaust system

Post by Deanxm »

lancia58 wrote:The HC is 153

Zohar
It should be about 5ppm - 20ppm, the limit is 200ppm but all my cars run below 30ppm, its just a measure of unburnt fuel, 153ppm is rather high indicating a problem.

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Re: Xantia - Bad smell from the exhaust system

Post by CitroJim »

Indeed, a dirty air filter, a slight misfire due to a bad plug or tight valve clearances.

A goods service normally sorts it...
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Re: Xantia - Bad smell from the exhaust system

Post by lancia58 »

Hi

Can it be that the ignition coils are not at their best ? Is there a way to check the ignition coils with the Lexia ? It has been so since I bought the car two years ago and in that time period I changed the spark plugs and the air filter twice. Can a defective fuel pressure regulator cause this ?

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Re: Xantia - Bad smell from the exhaust system

Post by CitroJim »

lancia58 wrote: Can it be that the ignition coils are not at their best ? Is there a way to check the ignition coils with the Lexia ? It has been so since I bought the car two years ago and in that time period I changed the spark plugs and the air filter twice. Can a defective fuel pressure regulator cause this ?
Ignition coils either work or not Zohar. They normally fail by causing a very obvious misfire, often when hot. A lexia will show any stored faults relating to the coils.

Yes, a duff fuel pressure regulator could well cause it. The Lexia can't tell you that except perhaps indirectly by reporting the the mixture adjustment has reached the limit but it's not hard to plumb in a pressure gauge on the fuel rail to see. Normally Xantias are set at 3 bar pressure but some (often with Magnetti Marelli injection) are set at 2 bar. If a 2 bar regulator has been replaced by a 3 bar one then that might cause it. It's easy to replace with the wrong one as they look absolutely identical and you need to look carefully to see what their pressure setting is.
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Re: Xantia - Bad smell from the exhaust system

Post by DHallworth »

I believe a reading on your lambda sensor like that is normal as it's switching when the reading is jumping.

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Re: Xantia - Bad smell from the exhaust system

Post by lancia58 »

How do I plumb in a pressure gauge on the fuel rail ? Can the ignition cables be a source for high HC ? Can a clogged injectors be the source for high HC ?

Zohar
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Re: Xantia - Bad smell from the exhaust system

Post by DickieG »

lancia58 wrote:How do I plumb in a pressure gauge on the fuel rail ?
You'll need a 'T' piece hose joint and a short length of fuel hose, remove the fuel hose where it attaches to the fuel rail and fit the 'T' piece with the gauge attached to one of the outlets.
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Re: Xantia - Bad smell from the exhaust system

Post by lancia58 »

If there is a vacuum leak how can it be located ? Are there hoses that are more prone for a vacuum leak ?

Zohar
Xantia 2.0 16V Automatic make year 2000 LHD
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Re: Xantia - Bad smell from the exhaust system

Post by lancia58 »

Hi

I found out that the idle stepper motor is faulty, the idle is not stable. I used the Lexia to check it and after that at idle the motor stopped. The only cure was to hit the stepper motor , ( I guess it released the actuator ), the idle it still not stable but at least the engine doesn’t stop. I already ordered one out of eBay. Can a faulty idle stepper motor be the cause to the high HC ?

Thanks
Zohar
Xantia 2.0 16V Automatic make year 2000 LHD
Citroen C4 THP Automatic make year 2009 LHD
Citroen C4 VTS 2.0 16V make year 2006 LHD
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