Altitude sickness?

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JohnD
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Altitude sickness?

Post by JohnD »

Here's an unusual fault mentioned in this month's Caravan Club Magazine. A bloke has had a Xantia HDI from new (2000). He finds that for the past three years, when he tows in mountainous regions on the Continent, the car experiences a sudden power loss, accompanied by the lighting of the fault light. He says the fault has been investigated six times, without success, by various Continental Citroen agents.
Anybody with a theory?
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benj
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Post by benj »

Caravan Club Magazine! bet thats a hoot!
(sorry)
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Post by AndersDK »

John -
It's common knowledge from my old books - that carburetted engines had to re-jetted for a richer mixture - if the engine had to work constantly at "elevated altitudes". Even my pretty recent Briggs & Stratton user's manual has this notice [:)]
My guess is that the Xantia HDI in question does as it should :
The ECU compensates the enrichment to try keep up the power - but because of the extra load from the towing - the enrichment passes the limits set by the Lambda value - and the ECU momentarily shuts down enrichment & power - to protect the catalytic converter.
My bet is that this is NOT peculiar to the Xantia HDI - but would also be valid to any other HDI derivative of different manufacture.
Waddaya think ?
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Post by tomsheppard »

Sounds likely to me...
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Post by MW »

Ho ho, happy memories of driving up to Andorra from the Mediterranean in a petrol Rover 214i. That car was quite heavy - but thanks to its tightly-tuned injection it got 100-odd bhp out of a 1400 engine, which wasn't too bad for 1987, although it wouldn't be considered all that special these days.
Anyway the final stretch across the main pass into Andorra is a one in 12 gradient at something above 8,000 feet. I was doing OK until the car in front of me slowed down for some reason - and that was the end of my momentum. I was down into third, then struggling, then it was second gear, then a couple of failed attempts to get it back into third, and I eventually finished up crawling up this long slope at 20 mph with the engine yelling "change up for chrissakes!" at me.
And all the VW Golf drivers with their underloaded 1.8 engines laughing at the poor old underpowered English.......
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Post by muunster1 »

the ecu uses an atmospheric pressure sensor to calibrate all pressure sensors at start up ,if the sensor goes outside the parameters set in the ecu for the region it was set for the ecu senses a a dramatic change in pressure on another sensor , it then assumes a fault has occured and derates the engine, the dealer should be able to change the program in the ecu for any region with difeerences in atmospheric pressure.
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Post by wheeler »

it wont need to be re-programed,like you say it takes an atmospheric pressure reading at start up.on later HDi's this pressure sensor is integral inside the injection ECU so it constantly monitors & adjusts as neccisary.
Anders,these engines don't have lambda sensors,do you mean it has an estimated lambda value worked out by the ECU ?
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Post by AndersDK »

Wheeler -
Does these cars not have the cat converters ?
That would be the only reason to have a lambda sensor in the first place.
If no Lambda sensors - then I could only guess that the engine/ECU for some reason is not able to compensate for both the towing & high altitude extra loads. It may simply reach a set limit - which is there for other reasons - like protecting the engine against a possible (thought) overload.
On ancient carburetted engines this limit was simply reached by the physical limits on the carburettor calibrations.
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Post by JohnD »

Xantias and 406s are very popular towcars in the caravanning world, especially since the advent of the HDI engine. In the recent Caravan Club Towcar of the Year, the HDI Berlingo came second in it's class. With the exception of a C5 HDI, this guy's trouble is the first time I've heard of the fault. Certainly my own 2.1 tows very well in Continental hilly districts.
When I read the letter in the mag, my first thought was that a faulty sensor was telling the governor that maximum revs had been reached. He doesn't say so, but I assume that once the engine is switched off, then started again, performance is back to normal.
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Post by wheeler »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by JohnD</i>

my first thought was that a faulty sensor
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote"> that would be my guess aswell,the injection system should compensate for different altitudes.
Anders,they do have cats but no lambda sensors,i've never seen a diesel with one.
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