The trusty A3 with problems! Could it be supermarket fuel?

[timmythechef]

As some may know, my a3 went into an Audi VW specialist in cardiff, with a suspected blown turbo at 45k.

It came back out, with a new air intake pipe, (the large plastic one at the top) Before it went in, it sounded like a police siren, and loss of power. It came out, the main mechanic told he took of the turbo and inspected it, he said theres nothing wrong with it, showed me a graph of my car on boost, everything is normal. He said these turbos can make a bit of noise after being mapped. But i still wasnt convinced this amount of noise is normal even if the turbo fine, its amost like its struggling.

Now it sounds not as bad as it went it, but still doesn't sound 100%, and the fiance whilst driving behind me this morning noticed alot of white smoke, so i phoned up the guy, and told him, he did say when i pulled off from him that he noticed some aswell, but thought it was because the turbo has been on and off the car. But went onto say if i use supermarket, I said yes as its cheaper and on the way to work so quicker to me!

He said the supermarket fuel may be causing the white smoke as its not burning correctly in the engine, as maybe causing the turbo to sound like its struggling, as the siren noise is worst when the car has turbo lag.

As i only have less than quarter of a tank, i will run this theory, what do you think?

 

[timmythechef]

I should say, since i filled the car up with this batch of asda's finest, its the only time its ever made this noise, could just be a coincedense?

 

[audigex]

It could be related, it could just be coincidence - only one way to tell.

That said, supermarkets and other garages often share fuel. They may all come from the same refinery in one area to save on transport costs.

 

[timmythechef]

Yeah, i thought it wouldnt be a difference, unless its just a bad 'batch' of fuel this time

 

[SAiLO]

Sorry my phone decided to dislike the post above.
Don't think the bad fuel would cause symptoms so similar to the turbo going.

 

[davoaj]

Not sure about supermarket fuel causing excessive noise or the white smoke, but I would certainly recommend using nothing but premium unleaded from shell, BP etc rather than supermarket fuel especially in a mapped car.

Supermarkets may share fuel in a geographic area but they won't be sharing it with Shell and the other petrol companies. I'm pretty sure that even the premium petrol on the supermarket forecourt only gets its increased ron rating by the addition of ethanol rather than being a naturally higher octane rating as per the likes of v power and ultimate.

Hope you get it sorted.

 

[paddy]

As a rule of thumb Black smoke is petrol, Blue smoke is oil and white smoke is condensation or water. I have come across water in forecourt tanks before but it sinks to the bottom and dosnt normally get into the system. Keep an eye on your coolant level for now,

 

[danb986]

I have to agree with davoaj. The supermarket fuels have way less additives than the likes of BP and Shell. This was very evident on the Mk4 Golf TDi's that had been mapped. If you filled up with supermarket fuels then you'd get a lot more diesel smoke than if you filled up with regular Shell diesel.
In the diesel section of the UKMKIV's forum, there was a lot of discussion on this and it was discovered that Sainsbury's caused by far the worst amounts of smoke out of all the supermarkets.
I'm not sure if your's is a petrol or diesel, but I imagine that the same quality differences apply to petrol as well as diesel.

(I'm not saying the white smoke is from the fuel, as what Paddy says about the colours is true, I'm just saying that supermarket stuff is definitely inferior to your premium fuels)

 

[timmythechef]

It's a diesel guys! I have checked the coolant levels, are fine and havent dropped. Also, though out this, the car has no recorded a fault, would there be an engine management light come on it if was the turbo?