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S80 '06-'16 / V70 & XC70 '07-'16 General Forum for the P3-platform S80 and 70-series models |
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Lumpy Start When Cold - Not Glow PlugsViews : 1405 Replies : 20Users Viewing This Thread : |
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May 20th, 2018, 09:44 | #11 |
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Yes. When we bought it it was 2 years old and turned to 47000 miles on the way home. It is now 10 years old and has nearly 116000 miles on it. Had it checked at Volvo dealer and the couldn’t see anything and had it looked at at my local garage and had the same outcome. Both said they did not think it had much wrong with and if it is working leave it alone. But it annoys me that it should not do it.
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May 20th, 2018, 12:57 | #12 |
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Have you actually checked that correct voltage is getting to the glow plugs?
I know the plugs are new but do they all work? Have you tested them, I work at a garage and it has been know to get faulty ones. When I had one glow plug down it took a little longer to start and and was lumpy till warmed up. Ps did you do the leak off test? https://photos.app.goo.gl/HqBmrkLgVuqRbjXi8 That was the results when I did mine last year, ran for I think 2 mins. You would need to check but sure it was less than 40ml in a minute was ok.
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S80 P3 SE LUX D5 Auto Last edited by Waynedance; May 20th, 2018 at 13:01. |
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May 20th, 2018, 13:25 | #13 | |
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Also worth checking is how much current each glow plug is taking, bypassing the glow plug relay to ensure the plugs get full battery voltage/current (in case the relay is past its sell-by date), preferably individually using a beefy ammeter (cold glow plugs will pull somewhere in the region of 30-40A each which drops as they heat up) to see if there is a weak plug or maybe more than one. Sadly the OP seems to have missed my original question and a couple of others from other members asking useful questions. Hopefully he will re-read the entire thread soon and get back to us!
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May 22nd, 2018, 22:22 | #14 |
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Hello again.
Thanks for all the inputs. Not had a chance to get under the bonnet yet. May get some time this weekend. I’ll check the voltage getting to the plugs. I don’t have an ammeter that does more than 10 amps so I’ll maybe pull all the plugs and earth them, hold the start button without the brake depressed as that seems to activate the glow plugs (according to the dash). At least then I should be able to observe them glowing? Failing that, I assume it could be injector related from other stuff I have read. I just chucked a bottle of Forté in so I’ll see if that changes anything. Then I guess it is time for a leak off test. It does sound slightly off beat or is that normal for a D5? Or, just not bother as it is livable with, just annoying 😪 |
May 22nd, 2018, 22:34 | #15 |
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If you can find either an auto electrician or electrical engineer among your friends who just happens to have an ammeter capable of reading high currents then you could test them properly. Depending on the ambient light, you may not see them glowing, if you have an infra red thermometer you could read the temperature after say 5 seconds and check they all reach a similar temperature.
Best method is individual current measurement though, assuming you get battery voltage at the glow plugs in the first place. If you don't, the glow plug relay could be suspect. To check that, you connect the voltmeter between battery +ve and the glow plugs, switch the glow plugs o and observe the voltage drop which should be negligible.
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May 23rd, 2018, 01:26 | #16 |
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Forgive my ignorance but does this engine have a coolant temperature sensor providing the ECU with data used to adjust fuel injection? If so might it be failing and convincing the ECU that the engine is hotter than it actually is. I know this can be a problem with petrol engine cars but my experience with diesels is not extensive, even though I now own one!
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May 23rd, 2018, 10:10 | #17 | |
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Also the usual thing is when the coolant temperature sensor fails it goes high resistance which generally tells the ECU the engine is in Siberia so the ECU overfuels - this is generally safer for the engine as there is less risk of it running lean and burning pistons although if left undetected can cause rapid bore wear due to "fuel wash". Because diesels don't actually have a throttle butterfly, the engine speed is adjusted simply by the amount of fuel injected - that's why when someone buries the loud pedal in a diesel, a big cloud of black smoke comes out the back end - over-fueling. From everything i've read so far on the symptoms of this car, the engine speed is about right so the right amount of diesel is being injected. However it's not running evenly until warm suggesting an imbalance on the pre-heating. It could of course be an injector problem but the OP has put some Forté in the tank which should sort the injectors out by cleaning them - time will tell if this sorts it or not but there's a strong likelihood it's the glow plug relay as all the symptoms are pointing to the pre-heating. The car has done 100k miles, has had a new set of glow plugs because it was presumably giving the same symptoms, next thing in line is the glow plug relay but the voltage drop test i described above should have been done after fitting the new plugs to make sure the relay was giving its best. In fact it should have been done before renewing the glow plugs to eliminate it from the equation in the first place. Glow plug relays do wear out, they pass a lot of current (typical 4-pot engine, the glow plugs initially pull about 120+A until they warm up then still about 30-40A usually) so it's not so much of a shock that it's the likely cause (if that is what it proves to be) and who knows how many starts that engine has had? Each takes its toll on the glow plug relay, whether hot or cold.
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May 30th, 2018, 23:52 | #18 |
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Thought I would update on this.
The forte injector cleaner a has sorted the problem. I though it was maybe just that the mornings had got warmer but now I am happy that with the recent colder mornings again, the symptom has gone. So, dirty injector(s) impeding atomisation or maybe sticking open a bit and resulting fuel pooling? Dunno but happy with the injector cleaner. |
May 31st, 2018, 00:01 | #19 | ||
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Most likely all the injectors were filthy, covered in carbon (they inject directly into the combustion chamber so are burned every time that cylinder fires) and/or leaking slightly as you summise. It's worth running a second lot of Forté through now and then do it once a year or so - first lot got rid of the problem, second lot now will clean the injectors enough that they last another year then you should be ok just doing it once a year.
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May 31st, 2018, 00:05 | #20 |
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Seems like a good buy: https://www.ebay.co.uk/itm/Forte-Adv...4AAOSw5bFZY4Od
I paid more but have just bought another here. |
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