I've been recently having the following CEL.
1 Fault Found:
17536 - Fuel Trim; Bank 1 (Mult): System too Lean
P1128 - 35-10 - - - Intermittent
Readiness: 0000 0000
As you can see it has been intermittent. It is on for two days and off for a week and then back on and then off again. Using the manual to check the code, the following suggestions are made:
Fuel injectors checking
Fuel pressure regulator and residual pressure checking
Fuel pump checking
Intake system checking for leaks (unmetered air)
Secondary Air Injection (AIR) system components removing and installing
After some forum searching, I am also assuming it may be my MAF. While the CEL was on I checked the mass of the air flow and logged a few values. These values are simply a two second snapshot of the entire log. Below is a legend for the columns.
C1 = RPM
C2 = Engine Load (%)
C3 = Injector Average over time (ms)
C4 = Air mass drawn in (g/s)
C5 = Lambda before cat. (%)
Logged readings from VAG-COM below:
C1 - C2 - C3 - C4 - C5
6240 - 84.2 - 16.66 - 101.06 - 25
6520 - 82.7 - 16.32 - 101.81 - 25 ---------REDLINE
4800 - 103 - 19.04 - 98.42 - 21.9
The value of 101.81 g/s air mass drawn in may flag my MAF as being the culprit. Ross-tech suggests this value should be about 80% of the horsepower at redline and since it reads also as (Mult) it should point to the MAF. So, presumably, I should be seeing around 136 g/s drawn through the MAF on my bone stock 2001 Audi A4 1.8T B5 AWM. Over the past couple of months I have felt some horsepower loss and this should be evident of that. I wanted to get any suggestions before assuming its the MAF and not one of the other suggestions made by the manual.