Volvo D5 Euro 4 low power - Help!
Discussion
Sorry, this is my first post here and I'm on the blag for help. If anyone reading this can help me nail down root cause(s) for the fault on my car, I'd be very grateful. I've posted this on the Volvo P2 V70 forum, but footfall there is decreasing, so thought I'd pop it up on PH, too. Facebook Groups and AI have been worse than useless, as has the Haynes workshop manual.
I have a 2007 Volvo V70 D5 Auto which I bought at 49,000 miles and which is now, 4 months later, on 53,000 miles. The car had come straight off someone's drive and had only done 4500 miles since 2019, so I had assumed it had been used for a lot of short trips and some recommissioning would be required.
Issue is that the engine is a bit shakier and noisier than it should be and suffers a noticeable reduction in power. This is my 3rd V70 D5, so I know what it should feel like and very occasionally from cold I get about 10-20 minutes of that before it goes back to being wheezy.
- There is no untoward smoke of any colour from the exhaust.
- There is no noticeable coolant or oil loss.
- There are clear signs of positive crankcase pressure - glove inflating, chuffing from dipstick tube. I have been told by reputable mechanics that this positive crankcase pressure is 'normal'.
- I recently disconnected the MAF and it did run slightly smoother on the default map. Upon reconnecting the MAF, VIDA (Volvo's proprietary diagnostics system - which I have here) reported a low voltage fault from the MAF triggering an engine warning light, but the light and fault disappeared after 50 miles or so.
- VIDA currently reports no faults (apart from a failed alarm siren board) but a cheap generic reader throws up a bunch of powertrain fuel/air faults. VIDA also reports correct DPF regeneration cycles and no EGR faults.
- The TCV and all engine mounts have been replaced.
- Car came with 16 service stamps and paperwork, so I'm leaving a full fluids & filter service until I've got to the bottom of this issue.
I think the root cause is one or all of:
- Failing MAF sensor
- Blocked Crankcase ventilation system
- EGR not actuating properly
I have a new Bosch MAF ready to go in, but before I fit it, I'd like to try and figure out for sure if there's an issue elsewhere...What I think I need to know is....
- is the positive crankcase pressure an OK thing or does it need fixing? I am unconvinced this is correct behaviour and think the ECM and MAF assumes air entering the turbo inlet from this system and blockage may result in wonky MAF behaviour and the ECM under fuelling.
- How do I definitively tell if the EGR is working properly via VIDA?
- Is there anything else I may be missing here?
Any advice would be gratefully received.
TIA
I have a 2007 Volvo V70 D5 Auto which I bought at 49,000 miles and which is now, 4 months later, on 53,000 miles. The car had come straight off someone's drive and had only done 4500 miles since 2019, so I had assumed it had been used for a lot of short trips and some recommissioning would be required.
Issue is that the engine is a bit shakier and noisier than it should be and suffers a noticeable reduction in power. This is my 3rd V70 D5, so I know what it should feel like and very occasionally from cold I get about 10-20 minutes of that before it goes back to being wheezy.
- There is no untoward smoke of any colour from the exhaust.
- There is no noticeable coolant or oil loss.
- There are clear signs of positive crankcase pressure - glove inflating, chuffing from dipstick tube. I have been told by reputable mechanics that this positive crankcase pressure is 'normal'.
- I recently disconnected the MAF and it did run slightly smoother on the default map. Upon reconnecting the MAF, VIDA (Volvo's proprietary diagnostics system - which I have here) reported a low voltage fault from the MAF triggering an engine warning light, but the light and fault disappeared after 50 miles or so.
- VIDA currently reports no faults (apart from a failed alarm siren board) but a cheap generic reader throws up a bunch of powertrain fuel/air faults. VIDA also reports correct DPF regeneration cycles and no EGR faults.
- The TCV and all engine mounts have been replaced.
- Car came with 16 service stamps and paperwork, so I'm leaving a full fluids & filter service until I've got to the bottom of this issue.
I think the root cause is one or all of:
- Failing MAF sensor
- Blocked Crankcase ventilation system
- EGR not actuating properly
I have a new Bosch MAF ready to go in, but before I fit it, I'd like to try and figure out for sure if there's an issue elsewhere...What I think I need to know is....
- is the positive crankcase pressure an OK thing or does it need fixing? I am unconvinced this is correct behaviour and think the ECM and MAF assumes air entering the turbo inlet from this system and blockage may result in wonky MAF behaviour and the ECM under fuelling.
- How do I definitively tell if the EGR is working properly via VIDA?
- Is there anything else I may be missing here?
Any advice would be gratefully received.
TIA
Diesels do not have a _positive_ crankcase ventilation system, as they dont produce their own vacuum (why you have a vacuum pump for the brake booster) the crankcase ventilation system is passive.
Every D5 I have ever seen breathes heavily if you take the filler cap off - this is perfectly normal as thats an easier route out than the amount being dragged into the intake by the venturi effect.
Every D5 I have ever seen breathes heavily if you take the filler cap off - this is perfectly normal as thats an easier route out than the amount being dragged into the intake by the venturi effect.
First thought would be injectors, if the car has done few miles over extended periods they could easily be a bit sticky etc.
I had a set (in a d2) tested/checked out (can't remember by where) and 3 needed replacing with reconditioned ones by these guys https://wtdiesel.com/ and found them pretty good, it made the world of difference.
ETA
You could also check in ViDa to see if any of the injectors are maxxed out by adaptations & do a reset/recal.
I had a set (in a d2) tested/checked out (can't remember by where) and 3 needed replacing with reconditioned ones by these guys https://wtdiesel.com/ and found them pretty good, it made the world of difference.
ETA
You could also check in ViDa to see if any of the injectors are maxxed out by adaptations & do a reset/recal.
Edited by E-bmw on Thursday 7th May 14:34
dingg said:
I'd run it to low level fuel ,whack a load of injector cleaner in and run till the tanks empty.
If that doesn't work ,swap maf.
First two easy steps then reassess
Better still, renew fuel filter and, instead of filling the pot with fresh diesel, fill it with injector cleaner, so that the injectors get some of it neat. It's an old trick that has got many a diesel through the MoT If that doesn't work ,swap maf.
First two easy steps then reassess
IIRC, your filter is on the rear subframe, it's a very easy filter to access and change to access (once it's up in the air).
Oh, yes fuel filter is a good call - seen it twice now, sporadic loss of power eventually culminating in limp mode, in both cases a fresh filter sorted it.
Give the housing a good clean out with some brake cleaner while you are at it, the one I just changed on my fathers recently acquired XC90 was full of....grey....stuff.
At 2007 you'll have the [ford cost cutting i guess] plastic housing. I wouldnt do it on a Sunday if you need the car the next day lol.
Give the housing a good clean out with some brake cleaner while you are at it, the one I just changed on my fathers recently acquired XC90 was full of....grey....stuff.
At 2007 you'll have the [ford cost cutting i guess] plastic housing. I wouldnt do it on a Sunday if you need the car the next day lol.
Edited by chris1roll on Thursday 7th May 17:02
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