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Coolant temp sensor.

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Nikolaj   
Sun Oct 06 2019, 09:10pm
Joined: Aug 29 2019
Member No: #4047
Location: Roskilde
My 2,7 starts to "cough" just as it reach normal operating temp on the dash display, it's like when I turn off the choker on my old Jaguar a moment to soon.

After a few minutes it slowly gets back to normal.

Temp on the display are spot on, and stays there, but I guess that the engine management has it's own temp sensor, that may be a bit off!?

When I bought the car a few months ago in Germany, day temp was 30-40 deg. so this issue didn't reveal itself, until I got back to Denmark, and the day temp dropped to 20 deg. and below.

Any thoughts?

No error codes from Diabox.
C6Dave   
Mon Oct 07 2019, 07:01am

Joined: Oct 01 2009
Member No: #1
Location: Northumberland
Yes there is a separate 'coolant' temp sensor but if you have Diagbox it would be worth monitoring the engine readings before swapping out the sensor as it could be something else....
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cruiserphil   
Mon Oct 07 2019, 11:02am

Joined: Jan 24 2010
Member No: #38
Location: Celbridge
Hello Nikolaj,

As per C6Dave, live monitoring of the data with Diagbox might help. Faults may not be logged if the"fault" is not present for a set minimum time.

Regards,

Phil C.
Nikolaj   
Mon Oct 07 2019, 05:59pm
Joined: Aug 29 2019
Member No: #4047
Location: Roskilde
You're right, had the Diabox on today, (still finding my way around the menues) and temp says 88 deg. idle after driving home, so I guess thats OK.
It also caught me, I forgot to tighten a clamp for the tube to butterfly house, so low turbo presure.

I found a mesurement for "correction of injectors", I was looking for injector presure, (don't know if its something you can mesure with Diabox) but the value for the 6 injectors are quite spread out from 87 to 127, and when I check that some weeks ago, it was "only" 88 to 115.
How close do these values have to be for the 6 injectors, and at what level?

I do have a "sound", at light acceleration, it seems to dissaper under medium to hard acceleration, and that could very well be the injector on 127, a diesel like sound, if that injector is very poor in the low range, and more up to the game under medium to hard acceleration.

2 weeks ago I did a Bell Add "One Shot" treatment, in order to clean the injectors and system, but now it's like it switch betwen smooth and uneven running at lower speeds.

Thank you for your patience with us newbies, with only a couple of months C6 ownership under our belt.
C6Dave   
Tue Oct 08 2019, 07:21am

Joined: Oct 01 2009
Member No: #1
Location: Northumberland
Well the tech doc - Click Here - does say that using additives to clean the injectors etc. is 'forbidden' but everyone does it anyway

A dirty fuel filter can cause all sorts of issues and with winter coming it won't be long before diesel is sold with anti waxing agents which compound the problem. Where you are will dictate when those additives start appearing (and the refineries, sellers etc. don't really publish it)

As for measuring the injector pressures I can't find anything to say what they should be but on piezoelectric injectors there isn't a 'single' spray but several very fast ones from what I have read on a Jag forum using the same engine:

The solenoid-controlled injector does three "squirts" per power stroke, the first small "pilot" squirt just B4 top dead to heat up the combustion chamber even more than the natural compression-ignition principle. This speeds up the main burning when the main squirt comes slightly later, enabling the DIRECT injection system AND reasonable revs AND a better fuel economy than the older indirect systems with lossy swirl chambers in cylinder head. The third squirt after main-burn is to deal with NOX emissions

Piezoelectric injectors as fitted to your diesel Jag. are quite different, although they achieve the same objective in a better way. Instead of solenoids with their inertia, there is a stack of piezoelectric elements like a stack of very small coins inside each injector. A voltage of about 400 volt is applied across the stack, controlled by the ECU, and the stack gets ever so slightly longer.

This change is applied to an hydraulic amplifier (like a jack in reverse) which opens a valve allowing fuel to squirt. The force this can apply is truly enormous. This is all contained in the body of the injector. This system has virtually NO inertia, and is therefore extremely fast, so much so that there can be FIVE squirts per power stroke, resulting in even better fuel efficiency and even less combustion noise. The piezoelectric elements are well proved and tested, they have been around a long time in other common applications.


If that is the case, then it would explain the differing readings you have seen via Diagbox?
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Nikolaj   
Tue Oct 08 2019, 03:33pm
Joined: Aug 29 2019
Member No: #4047
Location: Roskilde
Fuel filter is next on my list, I like to change fluids and filters, when I get a "new" car, even that the previous owner and servicing Citroen garage, say it's been changed. Glowplugs was changed 2 years ago thay said, (I don't remember if the word "all" was included in the sentense) but it turned out that the 3 rear plugs was changed, and maybe they tried to start on the 3 plugs in front, 1 was broken, and the last 2 stuck, so thats another small project.

I tried to listen for a more noisy injector, but with no luck, so I might buy a test kit to measure the amount of returned fuel from the injectors, to get a rough indication, if one of the injectors are way off. (very simple/cheap tool from ebay)
C6Dave   
Tue Oct 08 2019, 05:40pm

Joined: Oct 01 2009
Member No: #1
Location: Northumberland
Fuel filter is next on my list, I like to change fluids and filters, when I get a "new" car, even that the previous owner and servicing Citroen garage, say it's been changed.


My car had a service last December at 123,000 miles with all the filters changed, I bought it in August with 126,000 miles on the speedo and after a trip to France I now have 128,600 miles on the speedo so I had the engine oil and filter changed whilst a new radiator and water inlet tank were fitted plus I reset the 'service schedule' to ' Arduous Conditions' i.e. 12,500 miles or annually given the car is not going to be used more than 5,000 miles per year (and I will try and avoid 'short' trips in it anyway)
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