MAF testing via Bluetooth OBD2 adaptor and Torque app for boost/performance issues

[KeithCheetham]

Below with thanks to maw_mk1_fabia from forum topic  - 

 

 

The app was the torque lite (free) on android (setup the OBD reader through the app, not the phones pairing options, that had me for a good half hour)

 

Make sure you're getting some data through live by adding an rpm display or something comparable.

Press the settings 'gear' button

Then press the settings 'spanner option'

-data logging and upload

-select what to log

--three dots in top right to add metrics (for mine I had manifold pressure, MAF, turboboost and vacuum gauge, engine rpm and speed [OBD])

-go back

-file logging interval (1 second for me)

-back out to the normal display

-gear button

-toggle logging (small info should appear at bottom saying logging enabled)

DRIVE

-gear button

-toggle logging (small info should appear at bottom saying logging stopped)

-gear button

-email logs

-csv

-email yourself and then open properly with excel or equiv (graphs don't like the timestamps it uses so I added an additional column to extract only the time part [formula =TIMEVALUE(MID(A2,11,9)) where A2 is the timestamp cell]

 

Shout if you need anything else

 

 Not a great recording but one thing of note is a very peaky MAF recording (driving around 30ish but peaking to 600+). Used the torque datalogger to make the quick and dirty graph below. Small snippet of a 30mph road and then the m1 slip (not perfect due to other cars but the spikes are evident).

 

I can give data if anyone is really bored but just to show the general behaviour 

Grey = revs

Blue = MAF (g/s)

Yellow = Speed 

Orange = boost (psi)

 

MAF is generally around the 30 mark but the peaks are 500+

 

 

What his graph does show is the MAF output is not scaling linearly, mostly nil output and spiking every now and again. i.e. It’s probably duff.

 

This morning I thought I'd test the MAF sensor using a multi-meter as per HatBoyHarvey's video on the tube - SKODA FABIA MAF (Mass Airflow Sensor) testing - YouTube - HatBoyHarvey - YouTube - (really useful playlist) and the cable was fine but the sensor was reading a lot lower than the one in the video (idle at 1.2V compared to ~2V and then revving it hardish it didn't go above 3V). I needed to pop around the corner anyway so thought I'd unplug the sensor 'just to see' half expecting a CEL and limp mode on the way. I WAS WRONG, the car had life! It could spin the wheels and drive like a normal car, got there and plugged it back in for a comparison on the way back and it was pathetic as like before.

 

This was the night and day difference I expected from the turbo swap TBH.

 

Few points because I couldn't find them on here before:

 

MAF readings do rise when engine idling, not sure why but they are reading ~550 g/s when stopped/slowing down as shown below (MAF is blue, revs are grey)

Town driving

 

Sliproad and motorway driving (same route as earlier graph (MAF follows revs pretty much)

 

Normal driving values are ~20-40 g/s

Motorway values are 40-90 (90 being hard overtake accel +70mph)

My old one was spiking (but not constant as above) and not reading above 35ish on the motorway.

 

My max boost (for that journey) is 16psi

 

The sudden jerky motion when taking foot off/putting on of the accel has stopped completely (following the MAF change) and the drive seems much smoother now.