Low mpg and butt-dyno power loss at low fuel

[Erikn89nl]

A few months ago I first started noticing my A3 had trouble starting sometimes. It would need to crank a few turns before firing up. Initially I thought it was a tired fuel pump, so I bought a Sytec replacement/upgrade from B5. Since fitting that, the problem sort of comes and goes.

Recently, I did an engine flush and inflated the tyres to a higher pressure (2.8 bar, which is 40-41psi). After doing this, my l/100km (metric mpg) improved from 8.3 to 7.5 on the dash. The amount of km's done at any given position of the fuel gauge was higher than it used to be, too. This was after the first 300km of a full tank of 98.

In the last 300km of that same tank of fuel, the reading on the dash went back up to 8.1. The car also felt slower, but I wasn't sure of that. The actual l/100km reading on the dash also showed higher numbers at any given speed, than it did during the first 300km.

So I concluded that all the improvements were just in my mind, even though the facts supported them. Then I filled the tank full of 98 again. And the power was back, the fuel economy was back to where it was after the engine flush.

Can this be caused by a bad FPR? or a poorly installed pump? I did do that job myself after all...

 

[Lodhiz]

Have you had your fuel filter changed at all? I recently carried out a service on my s3 comprising of a fuel filter change (as the car still had the original one) and I noticed my fuel economy was on the up. Even after spirited drives, I noticed the car wasn't drinking fuel as much as before.

I'm not too sure why, but with old filters I've read they can 'clog' up over time and have a negative impact on MPG. Worth a try and doesn't cost much for a new filter + 30 minutes of your time.

 

[Erikn89nl]

Boy did I... broke one of those damn clips, ended up bodging it with crap hose, which lasted 3 days and then squirted fuel over the motorway...

Suffice to say, it can't be that

 

[Lodhiz]

Ah damn! Not too sure then mate, it could be anything! Is your MAF ok? I know with faulty MAF's the fuel/air mixture is thrown out of balance and this causes poor MPG and in some cases power loss as well.

Either way, let me know how you get on...

 

[Erikn89nl]

MAF is only a few months old, but I've never logged it...