Member Since: 22 Sep 2021
Location: Devon
Posts: 11
Supplementary coolant temp
Hi all I’ve got a bit of a weird one on my manual disco 3 2005 2.7 diesel. Abit of diesel knock at all times and rubbish mpg. I’ve found this code as in the photo. Is there another temp reading? Or is this just a surplus reading. Any help much appreciated. Also all new injectors not for this issue. They were all fooked cheers
13th Aug 2024 10:25 am
Gary_P
Member Since: 03 May 2016
Location: Kent
Posts: 1596
No photo attached.Gary
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Discovery 4 HSE 2016MY
13th Aug 2024 12:42 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10577
no photo in your gallery
13th Aug 2024 12:43 pm
Drew0057
Member Since: 22 Sep 2021
Location: Devon
Posts: 11
Should be here
Click image to enlarge
Last edited by Drew0057 on 13th Aug 2024 1:09 pm. Edited 1 time in total
13th Aug 2024 1:04 pm
Drew0057
Member Since: 22 Sep 2021
Location: Devon
Posts: 11
Hopefully now
13th Aug 2024 1:06 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10577
Not seen that before.
It could be for a later engine
Any fault codes
13th Aug 2024 1:32 pm
Drew0057
Member Since: 22 Sep 2021
Location: Devon
Posts: 11
No no fault codes it’s only I noticed that due to the diesel knock I thought ode check injectors and temp sensors as I know some sensors won’t throw up codes. You might be right in saying it’s just a generic temp reading. Just crossing all the ts. There is another thread someone has a similar reading but 140 0c
13th Aug 2024 1:39 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4938
Drew0057 wrote:
Should be here
Click image to enlarge
It's a reference value for the PCM should the coolant temp sensor or others fail. On a cold engine (typically 20°C in these months) it will normally begin with a value separation of 8-10°C above the "actual" coolant and oil temp values!
(an actual coolant temp of 20°C = supplemental value of around 30°C) This separation will increase as the "actual" value rises, so by the time the engine is running a coolant of 90°C the supplemental will be in the range of 114°C.
Oil temp typically runs a bit behind the coolant temp, eventually catching up or exceeding it depending on conditions. Other parameters are also measured in a similar way, and act as an insurance to prevent engine damage or a dangerous operating environment. yµ (idµ - eAµ) ψ=mψ
13th Aug 2024 3:13 pm
Drew0057
Member Since: 22 Sep 2021
Location: Devon
Posts: 11
I get all that. Would you have any advice on where to check next? Thanks for your reply’s 👍🏻
13th Aug 2024 3:34 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4938
If you have no fault codes it's tricky to point a direction unless you still have historical codes for the reasons you renewed the injectors.
A faulty injector can and will damage a piston if left for too long, so it could possibly be something like that. However beyond a compression test, injector removal and a borescope is the only way to rule it in or out I'm afraid.
A garage with the right diagnostic equipment (Bosch BEA 850 or similar) and a technician who knows his or her way around it proficiently can do a passive compression test. This uses the starter current drawn for each cylinder compression stroke as a measure of cylinder performance. It's is a very quick, easy and noninvasive test to do once the fuel rail has been run dry, or the diesel EMS has been disabled. It can also be done at home with a digital cable clamp and a diagnostic interface on a lap top. The battery obviously needs to be in good health and fully charged or the results will be skewed. yµ (idµ - eAµ) ψ=mψ
13th Aug 2024 4:14 pm
Drew0057
Member Since: 22 Sep 2021
Location: Devon
Posts: 11
It’s been doing it since I got it 3 years ago. I did the injectors due to excess smoke on idle 3 of them were over the limit so changed all 6 after I noticed it. Never skips a beat just the slight knock when accelerating up to 4th gear low revs all other gears perfect. Just towed 400 miles no probs. The noise never gets louder always starts with no smoke not even when putting my foot down. Another thing could be knock sensors? I thought about fuel filter but that was changed last year when I did a big service. Again thanks for your reply’s
13th Aug 2024 4:39 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4938
Doubt it's a knock sensor as there is a myriad of codes for them if they falter. What do you consider poor mpg? On a long motorway run you should be seeing around 32mpg for a manual and 26mpg for local runs, less if subject to urban traffic.
Is there an aftermarket chip fitted (small black box)? They can often cause a "pinking" sound which was common on petrol cars 30 years ago and beyond.yµ (idµ - eAµ) ψ=mψ
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