Poor quality fuel?

[thismonkeyhere]

Recently filled my commuter with Diesel, from just under a quarter full, at a roadside 'main brand' filling station. Ever since I left the forecourt, my car seems to be slightly 'reluctant' and the mpg I am able to achieve has dropped off as well.

Could be a problem with the car, of course, but seems like quite a coincidence so I am thinking that I must have received crappy diesel of some sort.

Anyone have any experience or knowledge around this? Not something I've noticed before in my 22 years on the road, but I suppose it could have happened before to a lesser extent. Do the symptoms suggest the fuel could be poor?

[popeofmick]

When I drove an oil burner, I noticed subtle differences between different brands of fuel. So if you got a bad batch you would notice. Modern diesels are so highly strung when it comes to fuel not like the old days when you could run them on anything. Run the tank down then stick some premium stuff in or millers and it should return to normal.

[thismonkeyhere]

popeofmick said:

When I drove an oil burner, I noticed subtle differences between different brands of fuel. So if you got a bad batch you would notice. Modern diesels are so highly strung when it comes to fuel not like the old days when you could run them on anything. Run the tank down then stick some premium stuff in or millers and it should return to normal.

Millers?

By premium stuff do you mean 'diesel super' or whatever name they give it?

[Terminator X]

When I owned a 330d I once filled up at a station not normally used, on way home the cruise control felt weird as it was hunting up and down whereas it usually just sat at a steady pace. The car started to run worse and worse over next few days. Took it to a garage who were going to replace all the glow plugs (?) at some considerable cost. Just before work was due to be undertaken I filled up in the usual place and car was back to normal. Unsure if other fuel had water in it or I just filled up with petrol

TX.

[thismonkeyhere]

Terminator X said:

When I owned a 330d I once filled up at a station not normally used, on way home the cruise control felt weird as it was hunting up and down whereas it usually just sat at a steady pace. The car started to run worse and worse over next few days. Took it to a garage who were going to replace all the glow plugs (?) at some considerable cost. Just before work was due to be undertaken I filled up in the usual place and car was back to normal. Unsure if other fuel had water in it or I just filled up with petrol

TX.

Sounds similar.

Car is still pretty economical, despite the mpg drop off, so it'll be a while before I need to refuel. Wonder if it's worth 'topping up' with better stuff to see if it makes a difference?

[popeofmick]

Millers eco boost, you can get it from halfords, its an additive or premium diesel bp ultimate or shell v-power diesel. You might find the car improves with the current fuel as the ecu adjusts itself. it takes a few 100 miles for it to adapt.

[MrDecadent]

I had this on my old pd 1.9 vag lump. Turned out to be the MAF sensor, economy had dropped, hesitant acceleration – just didn’t feel as nippy as it did. Cleaned the MAF with electrical contact cleaner to diagnose and it was back to normal, but deterioted after 50 miles. Replaced the sensor and it was back to normal. I also thought it was bad batch of fuel and put some of the millers stuff in to no avail.

also i had no fault codes.

Edited by MrDecadent on Tuesday 26th March 12:29

[McSam]

Terminator X said:

When I owned a 330d I once filled up at a station not normally used, on way home the cruise control felt weird as it was hunting up and down whereas it usually just sat at a steady pace. The car started to run worse and worse over next few days. Took it to a garage who were going to replace all the glow plugs (?) at some considerable cost. Just before work was due to be undertaken I filled up in the usual place and car was back to normal. Unsure if other fuel had water in it or I just filled up with petrol

TX.

Don't go back to any garage that attempts to fix a problem like that on a warmed engine by replacing glow plugs!

[Speed_Demon]

It sounds like poor fuel, but one would expect quality control would be tight enough on such a product that only slight discrepancies in quality are allowed (... unless you went to Morrisons.

[thismonkeyhere]

Just been suggested that it could be the EGR valve in need of a clean.

So....

Fill up with something better, maybe with additive.

If no improvement then:

Clean EGR valve and/or MAF sensor.

Ho hum.

[blugnu]

My diesel runs a lot smoother with Millers in it - give it a go. Not something you want to do regularly as it's £10-£12 a bottle.

[thismonkeyhere]

Car duly 'medicined' with Millers and a top up of (hopefully quality) fuel.

We'll see.

[mat777]

thismonkeyhere said:

Clean EGR valve

Remove it altogether, youll get more power and better mpg. Its only there to bump the emissions down a few tax brackets when new

[colonel c]

Over the winter I've noticed that if I fill it up my TD5 disco with Supermarket diesel the fuel filter warning light that is supposed to indicate water contamination, will illuminate intermittently. After refilling a couple of times with BP Ultimate it stays off.
Make of that what you will.

[aw51 121565]

mat777 said:

thismonkeyhere said:

Clean EGR valve

Remove it altogether, youll get more power and better mpg. Its only there to bump the emissions down a few tax brackets when new

It's there to reduce NOx emissions in a Diesel engine, which are nothing to do with road tax banding; rather, NOx (the only downside to Diesel engines) are a precursor to photochemical smog - breathing in this stuff downstream of the local or regional city on a hot summer's day FTW?

Cynically/realistically - yes, blank the EGR off and sort the fault codes out .

[wheedler]

Does the car have dpf, it's possible it's trying to regenerate