Test drive - more EMS light woes

After the extensive work done so far:- new timing belt, front brake discs, rocker box oil leak, oxygen sensor, coil pack No2, exhaust mid section, fuel filter, fuel filler cover and brake fluid change it is time to give it attest run. All is now well with the work done so far except the EMS light has returned.

The latest code to be thrown up is P0171 -  Generic System Too Lean(Bank 1). This has been reset a couple of times but keeps returning. Also the car is gutless could not pull the proverbial skin off a rice pudding. The warnings about this problem are all on the web and it cannot be run to Rome with this defect  without damage to the engine.

We have various bulb failure messages including one real one indicating  the offside front flasher bulb has failed. I had a brief look and it is a bu..er to get out.

Forum/google wisdom says (*)

Reported error on the Gendan code reader: P 0171 Generic System: Too Lean (Bank 1).

Freeze frame data for above

LT FTRM (%) - 22.6

* The short fuel trim is derived from the computer trying to keep the engine at a perfect 14 to 1 fuel gas air ratio. It uses the signal from the o2 sensor and the map sensor and the mass air flow sensor. to come up with long fuel trims and short fuel trims. The short fuel trim is what is happening right know. The long fuel trim is what is happening over a long period of time. The goal for driveability  is the long fuel trim to be within 10% of 0
MAP (in.hg) - 17.1
* Manifold Absolute Pressure
1 Bar = 29.4 in. vacuum at idle is always high and typically ranges from 16 to 20 inches Hg in most vehicles.
Engine (RPM) - 709
* Normal tick over type revs so MAP is ok
CALC load (%) - 37.2
* I guess at the point of failure the engine was under some sort of load
COOLANT TEMP - 189
* 189degF = 82deg C quite normal
ST FTRM1 (%) -3.1
* As per previous note this is actually within range so the oxygen sensor loop, MAP and MAF  must be doing something.
Fuel Sys1 - CL, using H02S
* Closed Loop = Good , using oxygen sensor = Good

In summary the long term fuel trim is in error 22.6% it should be less than 10%, at the point of failure (freeze frame data) the MAP(in.hg) absolute pressure was in range. Most of the forums indicate the MAF (Mass Air Flow) and MAP sensor sets the fuelling from the ECU to the injectors.

I have therefore ordered a MAF sensor as the most likely cause of the problem based on the data and reading the forums.

The other likely cause is a leak in the inlet manifold but I have checked that with a butane aerosol and I cannot find a leak (like I did on a previous car).

Acronyms

FUEL SYS1 – Fuel System 1
•CL – Closed Loop
•OL – Open Loop
•Using HO2S – Using Oxygen Sensor
•FUEL SYS2 – Fuel System 2
•COOLANT TEMP – Engine Coolant Temperature
•ST FTRM1 – Short Term Fuel Trim, Fuel System 1
•LT FTRM1 – Long Term Fuel Trim, Fuel System 1
•ST FTRM2 – Short Term Fuel Trim, Fuel System 2
•LT FTRM2 – Long Term Fuel Trim, Fuel System 2
•Engine (RPM) – Engine Speed in Revolutions Per Minute
•VEH SPEED (MPH) – Vehicle Speed in Miles Per Hour
•IGN ADV (DEG) – Ignition Advance in Degrees
•IAT (°F) – Intake Air Temperature in Degrees Farenheit
•MAF (lb/min) – Mass Airflow in Pounds Per Minute
•ABSLT TPS (%) – Absolute Throttle Position in Percent
•O2S11 (V), (%) – Oxygen Sensor 1 Bank 1 Voltage and Percent
•O2S12 (V), (%) – Oxygen Sensor 1 Bank 2 Voltage and Percent
•O2S21 (V), (%) – Oxygen Sensor 2 Bank 1 Voltage and Percent
•O2S22 (V), (%) – Oxygen Sensor 2 Bank 2 Voltage and Percent
•OBD2 Stat – OBDII Standard Vehicle Conforms To