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Discussion Starter · #1 ·
This morning was my first frosty morning following the acquisition of the XJ earlier this year.

All good , below 4 degrees and both heated screens came on as per my Ford stable vehicles.

Top marks for the Webasto diesel fired water pre-heater too , warm air from the vents in under half a mile !

Diesels obviously take longer to warm up than a petrol as a rule , the pre-heater system is magic :-D


I could also visualise Phil.D this morning , pressing the rapid clear screen button and cursing ...... :evil: :evil: :evil:

This is as he turns of the heated screens to save the load on his alternator / electrical systems :mrgreen:
 

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........Top marks for the Webasto diesel fired water pre-heater too, warm air from the vents in under half a mile !Diesels obviously take longer to warm up than a petrol as a rule , the pre-heater system is magic .......
I just hope your Webasto heater keeps running properly. When I got the 2.7TDVi the FFH system had been locked out, which apparently they can sometimes do if they don't start properly or if the tank is low on fuel. So I got it re-enabled and it was great......for about two or three days before the problems started. It would fire up just fine, but sometimes after running for a few minutes it would go into what I called 'flame out' mode (like a jet engine) with the road behind me disappearing in a cloud of thick white smoke and people hooting and pointing at me! Most embarrassing. I was told that it was not dealer-serviceable, just fit new one. But new heaters are quite expensive, so the fuse was removed to put a stop to it.
 

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Discussion Starter · #3 ·
To be honest , I've not found exactly where it is located yet , on my to do list ....

Just happy that it works at the moment. Does the exhaust of it join the other exhaust somewhere ?

I have worked on a few cab heaters , caravan heaters in the past , probably very similar I'm sure.

Fingers crossed for warm air on tap through the cold mornings :)
 

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To be honest , I've not found exactly where it is located yet , on my to do list ....

Just happy that it works at the moment. Does the exhaust of it join the other exhaust somewhere ?

I have worked on a few cab heaters , caravan heaters in the past , probably very similar I'm sure.

Fingers crossed for warm air on tap through the cold mornings :)
Hi Eddie,
Assuming it's the same on a 358 as a 350, the unit is in the lower left corner of the engine bay (viewed from the front). There's not a lot to see - it's all tucked away in the corner - but there is a silencer and exhaust pipe, separate to the engine, which exits through hole in the underside of the bumper on the same side. If you get right down low you can see the hole and the end of the exhaust - watch out if it's running as the exhaust gas is pretty hot, so don't get too close!
 

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I could also visualise Phil.D this morning , pressing the rapid clear screen button and cursing ...... :evil: :evil: :evil:
This is as he turns of the heated screens to save the load on his alternator / electrical systems :mrgreen:
.

Wrong, oh suspicious one from the wilds of Milton Keynes :-D.

Phil did not rush the clearing process by switching on heating elements.
Phil started the car while feeding the Rabbits, Husky, Fish, etc, etc.

By the time Phil's generously proportioned buttocks touched leather, all was cosy and clear.

This will be life in N/W Herts for the foreseeable - although much improved today......

Phil.
 

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Ah though but ... this Jag has a power management system which turns off various high current loads (heated seats, heated steering wheel, screen heaters etc), even 'though switched on by the owner, if the load's too much for the gen and battery.
 

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Well I’ve been reading this thread thinking “I did not know that!”
So does this only happen if it gets below 4’ or does it kick in at another predetermined point? Having only bought mine in the summer, I’ve yet to go out in her in the colder weather...
 

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The Power Management System has been in the X350 since it came on sale, and seems to be a fairly sensible piece of kit to make sure the electrical load matches the output from the alternator/battery. A modern car can really put some stress on the generating capacity of the vehicle. In my 2003.5 Model Year technical notes it gives the priority of "shut-off" of components. It seems to be a fairly complex set of software and I never noticed anything not working in the time I had an X350 (2010-2016). However that car didn't have a heated front screen or heated rear seats. On my current X358 Sovereign I have heated rear seats and a heated front screen, but the seats are almost never used, and last winter, the screen cleared quickly using the electric elements. I suppose if one turns on EVERYTHING, then one might notice something not coming on, or not working.
 

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Never mind heated seats ... a heated steering wheel is just magic.
 

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Well I've been reading this thread thinking "I did not know that!"
So does this only happen if it gets below 4' or does it kick in at another predetermined point? Having only bought mine in the summer, I've yet to go out in her in the colder weather...
5 degrees if memory serves Glenn

All that smoke from the front bumper area at times can be really quite worrying, especially the first few times you see it lol

Jim
 

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This is what the Technical Guide for the Diesel (2006) says.

Fuel Fired Heater Operation
An electronic control module incorporated into the FFH controls the operation of the FFH system. The module monitors the ambient air temperature sensor and engine coolant temperature sensor. Two further sensors located in the heat exchanger provide the module with an input of the heat exchanger's casing temperature and coolant temperature.

The values from the sensors are used for FFH system adaptation between full-load, part-load and stand-by.
To minimize drain on the battery, the FFH switches from full-load to part-load, on reaching 87 C.
NOTE: The FFH will not operate if the battery voltage is below 10.2 volts.

Part-load operation offers the following benefits:
• Low noise output
• Low power operation
• Low fuel consumption Switch On / Starting NOTE: The FFH only operates when the engine is running.

During engine startup the FFH goes into stand-by. If the coolant circuit temperature is below 87 C and the ambient temperature is below 5 C the FFH starting sequence commences.
The glow plug is activated and after a delay the fuel-dosing pump commences operation; the fuel is ignited. The combustion air fan operation is then initiated.

The combustion air fan speed is increased in two ramps to nearly full-load operation. After a stabilization phase the combustion air-fan speed is again increased to full-load and the glow plug is deactivated.

After the above events have been completed the FFH enters 'Automatic Heating Operation', see below.

During automatic heating operation the glow plug functions as the flame sensor to monitor the flame condition. In event of a no flame condition, a restart is automatically initiated.

If the no flame condition persists, fuel delivery is stopped and the FFH enters an error lock-out with a timed shutdown of the combustion air fan to cool the FFH unit.

Automatic Heating Operation
The FFH is a 5 kW system and operates at two heat modes:
• Mode one delivers 5 kW (full-load),
• Mode two delivers 2.7 kW (part-load). The system operates:
• If the ambient air temperature is below 5 C.
• If the coolant temperature is below 87 C. Operating stages:
• The FFH operates at full-load until the coolant temperature reaches 87 C.
• The FFH operates at part-load when the coolant temperature is between 87 C and 90 C.
• The FFH switches to stand-by when the coolant temperature exceeds 90 C or the ambient air temperature exceeds 8 C.

The FFH will automatically switch between the above operating stages depending on the prevailing coolant and ambient temperatures.
NOTE: The FFH will not operate if the climate control system is switched off.
NOTE: The FFH will not operate if the low-fuel warning lamp is illuminated.

Switch Off / Deactivation
When the engine is switched off, the FFH is deactivated; at this point FFH combustion stops and a timed shutdown commences. The combustion air-fan continues operation to cool the FFH down, and is automatically switched off when a predetermined temperature is reached.
NOTE: The shutdown time and the combustion air fan speed depend on the FFH operating condition at the time of deactivation.
 

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Discussion Starter · #13 ·
Thanks for that info " Pat The Cat "
It's more than I had briefly found on Google in regards to its operation.

5 Kw is a fair sized heat output for such a small unit,
Explains my warm air within a few hundred yards :)
 

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5 degrees if memory serves Glenn

All that smoke from the front bumper area at times can be really quite worrying, especially the first few times you see it lol

Jim
I look forward to having a scary moment at some point in the very near future Jim
 

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Pat great write up, I’m sure the way the weather has turned it won’t be long before I find out if mine works ok!
 

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A couple of things to add:

I read somewhere that the fuel consumption is about one litre per hour (and the supply isn't part of the fuel metering for the engine, so it won't show up in the computer's mpg figure).

Apparently later ones were fitted a fuel restrictor in the supply in an attempt to stop the dreaded smoke - 'Ere Mister, yer car's on fire - phenomenon. Mine's May '08 (H285nn) and it doesn't smoke, unless ... unless you do a FFH pump prime (via the SDD) and then test run the FFH ... the car the vanishes <cough> completely.
 

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Discussion Starter · #17 ·
For those that feel the cold and would like it to work at , say 10 oC
They'll have to wire in a switched 5k variable resister across the external temperature sensor,
Adjust so that it reads 3 oC and hey presto , as Glen Fry would say ...... the heat is on !
A discreet " Water Heater " push button energising a timer on the resistor for 5 minutes,
Oh dear , that's another job I've given myself ........ Not really , I don't feel the cold.
 

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Discussion Starter · #19 ·
How can you tell if a car has a heated wheel just from looking at it? Does the wheel come on with the seats?
Mine seems to work sometimes but only with the heated seat on full.

It may be tied in with the external temperature as well ?

Time for Patrick to get copying and pasting to help us out :)
 

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All I can say is that it comes on with the seat heater although with mine the wheel doesn't seem to produce noticable heat when the seat is at the lowest, one led, setting; it only seems to get warm on the two or three led settings.
 
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