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Low Speed Loss of Boost. Takes along time to buildup.Views : 1582 Replies : 16Users Viewing This Thread : |
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May 29th, 2021, 12:14 | #1 |
2004 XC90
Last Online: Nov 2nd, 2021 23:27
Join Date: Sep 2017
Location: Norwich
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Low Speed Loss of Boost. Takes along time to buildup.
Hi all,
My car is a 2004 XC90 with 170k on the clock. Over the last few weeks I've had a 'Engine Service Required' Message pop up. Sometimes it'll clear if we're travelling along (Dual Carriage way speeds), but if at low speeds it'll hang around requiring a stop, engine off and back on to clear it. There is no black smoke emitted from the exhaust. MPG is its normal 29mpg. The fault code is generic on a handheld reader, P0244 "Turbocharger". The last state it failed in was:
A Genuine Volvo Fuel filter was fitted in 2020. Along with yearly oil changes and Genuine filter. The oil i used was Castrol Edge 5w-30, which now after digging away in the forums is probably incorrect and will be changed out for the 0w-30. The intercooler was replaced by myself in 2019 as it was cracked and leaking oil. The result of the crack has probably lined the intake system with gunk In the last few days the car now has zero boost from a standing start, pulling out of junctions requires some forward planning, the boost will slowly pick up and we're away. Driving along the road and increasing the speed doesn't produce the same effect, everything in the terms of boost is normal (which fairly slow as it's only 163bhp lol) I've investigated the Vacuum system, I get that popping noise I hear a lot about, but no matter if I blank off the Brake Booster and Nipple at the pump to the rest of the system, it'll still pop away. The Needle on my reader will not bounce around at idle and pulling a vacuum shows the tiniest of leaks on the engine mounts. 5Hg over a minute. The interesting bit is when I rev the engine up the needle will bounce everywhere, it's tee'd into the system straight after the pump, and this point I'm thinking how can things work if it can't pull a good vacuum. On the second go a short while later, when I rev the engine its build up more vacuum and hold releasing when the waste gate releases, quickly builds up and holds. I recorded this one and linked it here: https://youtu.be/CL8nBxZC5rk This leads me to think that something is effecting the vacuum intermittently, any ideas on what this could be? Moving my thoughts away from that, the car does a lot of short runs for School, would it be possible the Turbo Vanes are full of build up that needs cleaning? I'm going to run some Turbo cleaner through the fuel system to see if that'll make any difference. Maybe the actuator on the turbo is sticking and causing a boost leak? Cleaning of the MAP sensor would probably be beneficial. Can anyone recommend anything else I could try or clean before taking it to a specialist or dealer for diagnostics. Many thanks in advance Last edited by tomkirkland; May 29th, 2021 at 13:45. |
May 31st, 2021, 09:25 | #2 |
Master Member
Last Online: Apr 22nd, 2024 06:42
Join Date: Jan 2015
Location: Blackpool
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Morning , I had the same issue with my D5 , replacing the MAP sensor cured the problem , it was providing spurious values to the ECU . It is probably the cheapest item to replace . Hope this helps
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May 31st, 2021, 11:15 | #3 |
Premier Member
Last Online: Dec 26th, 2021 13:42
Join Date: Dec 2013
Location: Crewe
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In/Hg is a vacuum and is an incorrect value for the circumstances.
Check MAP (sometimes called intake manifold pressure) reading with engine off/ignition on, then at idle, then at 1k and 2k revs. Do the same for MAF and IAT or intake air temperature and report back.
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May 31st, 2021, 11:50 | #4 |
2004 XC90
Last Online: Nov 2nd, 2021 23:27
Join Date: Sep 2017
Location: Norwich
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Engine Off
Engine Idle
Engine 1000rpm
Engine 2000rpm
Looking at that my MAP sensor is going the wrong way meaning there's vacuum/flow issue or defective? Last edited by tomkirkland; May 31st, 2021 at 12:32. |
May 31st, 2021, 12:08 | #5 |
Premier Member
Last Online: Dec 26th, 2021 13:42
Join Date: Dec 2013
Location: Crewe
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You're showing kPa (positive pressure) and In/Hg (vacuum) at the same time so I'm not following your figures at all.
The dashes you're typing are adding further to the confusion. I don't know whether the dash means minus or something else. If a figure is a minus figure, type minus then the figure otherwise leave dashes out of your figures. Some actual screenshots would probably help. Also with MAF use kg/h or g/s as it saves converting to metric.
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May 31st, 2021, 12:11 | #6 | |
2004 XC90
Last Online: Nov 2nd, 2021 23:27
Join Date: Sep 2017
Location: Norwich
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Quote:
It does seem the pressure is increasing when at higher revs when it should be decreasing, which would mean I've got a restriction somewhere or a duff sensor? Last edited by tomkirkland; May 31st, 2021 at 12:17. |
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May 31st, 2021, 12:15 | #7 | |
Premier Member
Last Online: Dec 26th, 2021 13:42
Join Date: Dec 2013
Location: Crewe
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Quote:
lb/min for airflow on the other hand..... A space is fine for separation.
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