V50 Engine 2.0D : Increased fuel consumption

[Teddy1975]

My V50 2.0D from 2007 with the D4204T PSA engine has done 295k km/183k miles in total, with me doing only the last 10k.

I used to be able to average around 53.6 MPG / 19km/l with my driving but since last week it has plummeted to a paltry 36 MPG / 12.8km/l.

I haven't changed my driving style, there are no engine related codes set (I've checked with VIDA/DICE), and there is no huge cloud of black smoke trailing my car as I drive. There is just a very slight hesitation if I coast and then push the accellerator, and of course the fuel gauge going downwards way too quickly. It's no fun having 3/4 tank left and having the display say that you only have 450 km to go before the next refill. That's too much like what my old petrol 850 used to be.

I last had the car serviced in January and when I checked the oil level today, I saw that it is once again above the max on the dip stick and has a distinct diesel smell to the oil so I'll be draining it tomorrow and putting in some new fresh oil. There is a wet DPF system fitted to the car, which is working and topped up with EOLYS.

Does anyone have any ideas as to why the fuel consumption is suddenly so high? I'm not sure it is caused by the increased oil level in the engine but I just don't know what else it might be.

I'll be taking the car to a garage but it would be nice if I could tell them what to look for instead of them spending hours on troubleshooting.

Thanks a bunch,
Teddy

[Simmy]

no need to spend hours a good garage should have diagnostic equipment to point them to any underlieing faults.

[SnineT]

Pull the engine cover off and look for a fuel leak around the injectors

[Teddy1975]

No fuel leaks that I could see when I poked around it earlier, nor does it smell like diesel when the cover's off.

The owner of the garage I take my car to was astonished when I told him how poor mileage I get now without check engine or other warnings, then said that it might be a leak in one of the vacuum lines.

I'll change the oil early tomorrow morning then go have another word with him and schedule an appointment.

[SnineT]

Originally Posted by Teddy1975

No fuel leaks that I could see when I poked around it earlier, nor does it smell like diesel when the cover's off.

The owner of the garage I take my car to was astonished when I told him how poor mileage I get now without check engine or other warnings, then said that it might be a leak in one of the vacuum lines.

I'll change the oil early tomorrow morning then go have another word with him and schedule an appointment.

Dirty fuel filters can cause the mpg to get worse, I assume the air one isn't that old.

[Lancee]

If OP has ViDA, is it not possible to dig down and look at likely relevant parameters and check these with live data ?

[Teddy1975]

Fuel, air and oil filters were all changed in January, 10k km ago.

I drained 8 litres of oil/diesel from the sump this morning, put 4 litres of new oil in, which made the oil level reach the halfway mark on the dipstick. I left the oil filter in place as I will have it replaced when the issue is sorted. Draining the oil did nothing to improve the mileage, though.

Went and spoke with a couple of the mechanics at the garage after I drained the oil and they said that it was 90% certain that it is one or more of the injectors that're "sweating", which I suppose could make sense because even when coasting downhill now, the fuel consumption is at 1.5L/100km or 188 mpg where it normally says 0L/100km (close to no consumption at all).

Either that or one of the intake sensors is reading the wrong temp so it's running much too rich, but since that doesn't explain the diesel getting into the sump issue, they are leaning toward the faulty injector theory.

I mentioned what I've read about the fuel pump sometimes leaking on the 2.0d engine and they don't think that's the problem here because that happens so infrequently that it's more likely something else.

This garage is independent, but has about 8 full-time mechanics employed and from what I've heard they are very competent - that's my experience with them as well. Scheduled an hour or two of troubleshooting on next Tuesday as that was the earliest they could do it. Until then I need to drive the car another 400 km (5 trips to work), but will keep checking the oil level to make sure it doesn't go over the max level again.

[Teddy1975]

Originally Posted by Lancee

If OP has ViDA, is it not possible to dig down and look at likely relevant parameters and check these with live data ?

I do have VIDA, but I am far from an expert in using it and I don't know much about cars, beyond being able to replace some parts.

So, unfortunately I've no idea what parameters would be relevant or how to check those live data.

[Sidonas]

Does it have a DPF? From what I remember, clogged DPFs are often the culprit of rising oil levels in these engines.

[SnineT]

Chuck a fuel treatment in it as well, 250ml to half a tank and go out for a 50 mile + drive where you can give the old girl a proper whipping through the gears, no need to gun the nuts off her just progressive 4000 rpm building through the gears.