boost lag and fuel economy question

[hunker7]

"Finally working as it should" didn't last long, at least I think so. Basically what bothers me is the turbo lag, which makes car un-drivable around town. Audi says max torque comes in at 1950 rpm, of course I don't know how much truth there is to it, but mine is not even close.

3rd@2000rpm floor it and max boost (~2.5) is reached at over 4000rpm
2nd@idle floor it and it starts boosting at around ~2500rpm and properly starts moving after 3000rpm.

So I just want to know if that's how it should be, or something is wrong.

Seconds problem is fuel economy. Just to say I don't expect 50mpg but I genuinely think 11mpg is a bit too much, and it's 11 regardless of how I drive, floor it whenever I can or being light on the throttle.

No error codes and engine ticks over nicely. Timing is correct (triple checked).

Any help appreciated, as I am genuinely loosing patience.

[Error404]

11 is achievable if you try hard
Has it been like this since you put it back together?
I would envisage a mechanical issue or a knock sensor fault which can cause issues without throwing codes

[hunker7]

11 is achievable if you try hard
Has it been like this since you put it back together?
I would envisage a mechanical issue or a knock sensor fault which can cause issues without throwing codes

It has yes, as soon as I put it together I noticed the lag and fuel problem

Where do I start with this, I don't fancy spending hundreds on parts that are working fine. I inspected knock sensors when I had them off and they seemed fine visually with no cracks etc.

[220bhp]

Two things with knock sensors. The wire degrades, and the wrong torque setting.
The fact that there are no codes is a pain.
It took me along time to trace this issue when I first got my car. By then I had replaced just about everything.

[hunker7]

Two things with knock sensors. The wire degrades, and the wrong torque setting.
The fact that there are no codes is a pain.
It took me along time to trace this issue when I first got my car. By then I had replaced just about everything.

Knock sensors have been torqued to 20Nm

Could I test it by unplugging them one at the time?

[Error404]

With no signal from the knock sensors the ECU will cut boost and I assume also pull timing; you will be in limp mode.
I would say it seems more likely to be a mechanical issue since it's been evident since you put it all back together.
I would go back over everything that has been loosened, removed or fitted and check it all

[A80Avant]

You checked the timing with a strobe light?

This issue brings in mind the timing belt sprocket and the half tooth out issue. Car can be idling nice just different camshaft positions.

[hunker7]

With no signal from the knock sensors the ECU will cut boost and I assume also pull timing; you will be in limp mode.
I would say it seems more likely to be a mechanical issue since it's been evident since you put it all back together.
I would go back over everything that has been loosened, removed or fitted and check it all

All I had off was intake/exhaust sides and timing belt, and assembling you can't really put it back together wrong. I've been thinking and I can't think of anything that could have gone wrong.

You checked the timing with a strobe light?

This issue brings in mind the timing belt sprocket and the half tooth out issue. Car can be idling nice just different camshaft positions.

I've changed lower timing belt pulley, and you can't assemble it incorrectly as far as I know

Strobe on AAN?


Turbo itself had tiniest of movement, hoses are not in the greatest of shapes but there are no splits.

[A80Avant]

Sure you can assemble it incorrectly. Make sure the timing marks are always half tooth out. I'm sure there are images here. I have never done this myself as I'm not a mechanic but I see this issue coming up again and again

[hunker7]

Sure you can assemble it incorrectly. Make sure the timing marks are always half tooth out. I'm sure there are images here. I have never done this myself as I'm not a mechanic but I see this issue coming up again and again

How? Because lower pulley has a key way, and there is like a pin on it so you can fit the lower drive belt pulley.

Also, don't understand what you mean by "Make sure the timing marks are always half tooth out."

[slim100s4]

My s6 had bad mpg when I first got it sat at 18 mpg all the time. I changed fuel filter put some injector cleaner in and did the coil pack upgrade and now iam getting 23-24 around town and on a run last nite I was getting 32 mpg sitting at 60 and giving it the odd squirt overtaking.

[slim100s4]

I was surprised what mpg I was getting myself that's why I took the photo.

[hunker7]

My s6 had bad mpg when I first got it sat at 18 mpg all the time. I changed fuel filter put some injector cleaner in and did the coil pack upgrade and now iam getting 23-24 around town and on a run last nite I was getting 32 mpg sitting at 60 and giving it the odd squirt overtaking.

This is why I think something is wrong with mine. I have a new fuel filter, new filters in injectors and pump hasn't done loads of miles either, and I have TFSI coil conversion done.

Best I can do is 15mpg and that's planning ahead and basically not driving

Going to Leeds tomorrow so good 200 miles, I'll see what she does on a motorway.

[slim100s4]

Do you reset the trip computer?

[hunker7]

I reset it and drive for some time and it usually ends up at at a really low number.