V50 Engine 2.0D : Increased fuel consumption

[Teddy1975]

So, the increased fuel consumption, according to the mechanic who checked my car, was due to repeatedly failed DPF regens. He forced it to regen, which did burn off some particles with a nice white cloud of ash for about 10 seconds, then took it for a quick test drive and said that it seemed to drive fine now and told me to keep an eye on the fuel consumption and come back if it didn't improve.

I drove a 20 km long test drive afterwards, primarily straight and level country roads and I could just barely get 15 km/l or 35 mpg out of it. I went back to the garage and said it wasn't fixed. Now booked in for more troubleshooting next thursday.

This evening I've been on a short test drive with Vida monitoring the two catalyst temps, distance since last DPF regen and DPF pressure. I couldn't watch the monitor for the entire drive, obviously, but when I started the engine, the distance since last regen said 0 km, which I thought sounds consistent with the mechanic's suggestion that the increased fuel consumption is related to repeatedly failed DPF regens.

I tried to check the temps while driving and I saw one of them get close to 550c, but a few minutes later it had dropped down to less than 300c again.

The pressure was anywhere from 5 hPa to 45 hPa, possibly higher, but I don't know what the acceptable range is and when a regen should be triggered.

Anyway, before I just tell the mechanic to check everything and throw money at him until he finds out what's wrong, does anyone have any ideas of what to check?

During my own findings from reading this forum and the Swedish Volvo forum along the 9 months ownership I've had of this car, a DPF regen is dependant of:

Pressure sensor that is next to the battery box,
Pressure hoses, going from sensor to the DPF,
Glow plugs (?),
Glow plug relay (?),
Eolys additive.

Is there more than the above, apart from the DPF itself, which is only 45000 km old?

Thanks,
Teddy

[Simmy]

do a leak back test and do an injector test with vida

[Sidonas]

Any resolution to this?

[Teddy1975]

Well, yes and no.

I returned with my car for further diagnostics where the mechanic had a quick look at the engine and saw that to remove the return fuel lines from the injectors he would first have to remove the intake manifold. That might ruin the gasket so he wanted to order a new one, plus a new copper gasket for each injector. That was fine with me, but the parts wouldn't arrive until 2 pm in the afternoon which was too late to start working on the car. That was Thursday 8th.

I scheduled a new visit Tuesday 13th and when I got there, the owner explained how he had spoken to his backup engineering people who said that it might be due to a faulty reading from a sensor that their scanner might not be able to communicate with. So he suggested I'd go to Volvo and have them scan the car with a genuine scanner to make sure it wasn't something simple.

Volvo didn't have time until Friday 16th, and when I got the car back from 30 minutes of troubleshooting, the mechanic said that the increased fuel consumption was 100% because of a mechanic failure in the injectors, although he couldn't say which one, nor if it was one or more. He had tried to adjust them via Vida, but to no effect.

He said the elevated temp readings from the DPF is because of unburnt diesel getting to it and the rising engine oil level is also because of the excess diesel. The DPF isn't backed up and is still able to regen, the pressure sensor works, all glow plugs and their relay work.

I've scheduled a new visit at the indy workshop on Tuesday 20th to find out which injector(s) are faulty and hopefully have the culprit replaced on the same day. The owner told me there are 4 different types of injectors for this engine, two of which can be bought refurbished. The refurbished ones cost from £233 while new ones are from £365, per piece. So, naturally, I'm hoping for a single broken injector of the 'cheaper' version.

Even if it should be four brand new injectors, I have no other option but to have them replaced as I can't sell this car and buy another one that is in perfect nick without losing more money than the cost of this repair.

[Teddy1975]

And that was supposed to say Tuesday the 27th and not tomorrow...

[Teddy1975]

So, I fetched my car from the garage today. Managed 4.7l/100km or just a bit over 60 mpg on the way home so problem is solved.

The #3 injector was the culprit. Although everything seemed fine when they measured the return fuel from the injectors, one proved faulty when they were pressure tested yesterday at a Bosch diesel test centre. Fortunately, the test centre was able to locate a new injector for cheap that was overnighted to the garage and installed today.

Now I just need to wait for the bill to arrive...

It's so good having my car back in order.

[Teddy1975]

So, the saga continues.

Just as I thought all was well, only 200 km down the road, the fuel consumption increased again, like lightning from a clear sky.

Returned the car to the garage, where the mechanic looked just as puzzled and regretful as I felt. They had the car for 2 days where they tried a number of things and finally the owner rang me and said they weren't sure what was wrong with it. He suggested I had the rest of the injectors replaced and although not happy with that I decided to go ahead.

I got the car back Friday last week and it was a joy to drive, perky when I put my foot down and fuel efficient when I drove more sensible (I mostly do the latter but I do like the not having to plan for days before going to overtake someone). But, just as sudden as before, it started to guzzle fuel again.

I'm at my wits end, as is the mechanic who worked on my car. Why did it drive so well able of doing 61 mpg (4.6l/100km) for 150-200 km and then, boom, revert to 40 mpg (8l/100km)?

Also, when the engine is at temp, it is lurching/hesitating between 1600-2000 rpm in any gear which clears up immediately when applying more gas or decelerating. It also does this lurching when cruise is activated. It has done this since I bought it, so that's nothing new, and the mechanic first thought it was the EGR valve acting up, but now he thinks it could also be the turbo or perhaps the DPF.

I'm going for a drive tomorrow with Vida live logging some parameters to bring to him so he can hopefully see more clearly what is the culprit.

Just as great as this car is to drive when at its best, it's just become an abomination I'm itching to wrap around a tree so I can cash in the insurance to reclaim just a bit of the money I've spent on it. But, I'm not that kind of guy...

If for any reason you are on the market to buy a V50, do NOT buy one with a 2.0D engine in it. Just, don't.

[SnineT]

There should be a pair of O2 sensors underneath, one near the manifold area and one near the rear axle, suggest they check these are working ok, not saying it will be that but from what you say it's almost as bad as a fuel leak would look like, obviously it's not leaking but you get my drift.

[Sidonas]

As I've written before, rising oil levels - DPF problems. Have you checked wether the oil level has risen again?

As far as I'm aware, there are no O2 sensors in these diesels.

[Teddy1975]

I went to log several parametres in Vida the other day and before I set out, I erased all codes.

For the first 50 km, the consumption was appalling. For instance, city traffic at 50 km/h on a level road in third gear just maintaining speed: 15l/100km.

However, after those initial 50 km of driving, suddenly, like the flip of a switch, it went back to driving flawlessly. Mixed country road/town traffic came to 4.6l/100km. Now, after driving to work and back, it's at 4.9l/100km which is good. What isn't good is that there is no apparent reason for it.

I've got my fingers crossed that it will remain like this, if not, then I'll start looking if all the components involved in DPF regeneration are working as they should, although the mechanic says that failed DPF regen cannot be the cause of this. The DPF on my car is not blocked.

Rising oil levels can be from failed DPF regen AND injectors failing. In my case it was the latter.