Tolerance of MAF readings?

[caldy315]

I logged my MAF last night just of S&G's because of some recent discussion on my local forum. Followed Ross-Tech's tips one of which said for a stock turbo and such, your readings should be about 80% of your horsepower on a full throttle, to-redline pull. I did just that yesterday in 3rd gear and got 132 g/s (Boy, was that fun). I should if following to the letter, get 144 g/s. What's the tolerance on these? Really just throwing rocks, but my 3 year average fuel mileage is 23.5 mpg and that is rather low for a 1.8T 6sp quattro, especially considering local forum members get closer to the 27-29 mpg, some even tuned. I don't really care all that much, but the car has 175k on it and I haven't replaced it nor saw it replaced in the records since I got it (125k). Thought maybe there could be an improvement in mileage if one was due. If I could gain say 3mpg on a tank, that investment in a new MAF would pay for itself quick.

So the question is, what's the tolerance of the 80% of your horsepower rule? 10%, 5%? I'm at 8% different right now.

ALTHOUGH for some reason I thought the 1.8T in 2005 had 180 horspowers, but a little searching shows 170? If 170 hp, then I'm almost dead nuts on.

[old guy]

170 is correct.

[userbob0001]

Did all ultrasports have the 190hp engine? Could that be what caldy should be looking for? As I understand, the USPs had the BEX motor that had fewer power compromises for emissions. Pretty much everything I know on those details comes from here though.

[caldy315]

Did all ultrasports have the 190hp engine? Could that be what caldy should be looking for? As I understand, the USPs had the BEX motor that had fewer power compromises for emissions. Pretty much everything I know on those details comes from here though.

As far as I know being a USP owner, the only difference between USP and non-USP A4's is the aesthetics, wheels, front bumper, side skirts and rear bumper. The steering wheel and shift knob may be different, but I think that's it. My head has AMB stamped into it.

[old guy]

That is correct. The differences in The US versions are cosmetic only.

[userbob0001]

That explains some things. So 170*.8=136g/s sounds like 132g/s is a very good sign

[diagnosticator]

Any AMB will produce varying net output depending on weather conditions and engine mechanical wear material condition. While the published rating is 170 HP, Actual engine output will be different for any one AMB, easily +/- 10% more or less than the published rating.

The 80% MAF meter measured mass flow rate vs HP number is only a rough rule of thumb also. It's not possible to quote a defined tolerance for the MAF meter measured value.

The only accuracy tolerance of the measured mass air flow is as defined by Bosch, under standard lab conditions as the +/- variation from actual mass flow rate of the MAF meter .