GOLFMK8
GOLFMK7
GOLFMK6
GOLFMKV

Disconnected MAF sensor, engine runs better.

A

atikovi

Ready to race!
My 2010 GTI gets a bunch of engine codes such as all the misfire codes, P0606 Processor Fault, P2177 System Too Lean off Idle, P0101 Mass Air Flow Sensor (G70) Implausible Signal, P2188 System too Rich at Idle.

When cold it misses and the check engine light flashes. When warm it will miss as you come to a stop, sometimes it stalls. The tailpipe is black with carbon soot. I tried disconnecting the MAF sensor and it runs much better. I'll see tomorrow if the cold miss is gone but does it sound like a bad MAF sensor? Is there a way to test it?
 
DBESTGTI1

DBESTGTI1

Go Kart Champion
check the fuel trim, clear the faults, start it up and go to the basic setting for fuel trim and let it idle. See where the fuel trims go and how fast they get there.
 
P

prospal

Ready to race!
How would you go about finding what it should be? Someone else's logs?
 
B

bluescreenofwin

Ready to race!
Could be MAF sensor, vacuum leak, cracked intercooler, or leaking/cracked turbo intercooler hose

Pulled the diagnostic procedures (formatted for legibility):

MAF Sensor, Checking

Use only gold-plated terminals when servicing terminals in harness connector of Mass Air Flow (MAF) Sensor -G70- .
-Multimeter.
-Wiring diagram.
-The Mass Air Flow (MAF) Sensor -G70- fuse 1 in Fuse Panel C is OK.
-Battery voltage at least 12.5 volts.
-All electrical consumers such as, lights and rear window defroster, switched off.
-Vehicles with automatic transmission, shift selector lever into position P or N
-A/C switched off.
-Ground connections between engine/transmission/chassis OK.
-Coolant Temperature at least 80 °C.
-Ignition switched off.
-Perform a preliminary check to verify the customers complaint.
-Connect the scan tool.
-Start engine and let it run at idle.
-Using the scan tool, Check the air flow quantity of the Mass Air Flow
(MAF) Sensor -G70- at idle:

Diagnostic text / Specified value
Air flow quantity at Mass Air Flow (MAF) sensor Engine warmed up, running at idle / 2.00 to 5.00 g/sec

-If specified value is obtained, but DTC memory has a DTC concerning Mass Air Flow (MAF) Sensor -G70- :
Fault may be intermittent. Check the electrical harness connector for damage, corrosion, loose or broken terminals.
-If the specified value was Not obtained:

– Disconnect the Mass Air Flow (MAF) Sensor -G70- electrical harness connector -1-.
– Start the engine and let it run at idle.
– Using a multimeter, check the Mass Air Flow (MAF) Sensor -G70- electrical harness connector terminal 3 to engine Ground.
Specified value: battery voltage.
– Switch the ignition OFF.
If the specified value was Not obtained:
– Remove the fuse 1 in Fuse Panel C. Check the Mass Air Flow (MAF) Sensor -G70- electrical harness connector terminal 3 to Fuse 1 in Fuse Panel C for an open circuit.
Specified value: 1.5 Ω max.
If the specified value was obtained:
If the manufacturers test box is being used, perform the following step.
– Install the test box.
If the manufacturers test box is not being used, perform the following step.
– Remove the Motronic Engine Control Module (ECM) -J623- . Refer to the Repair Manual.

– Using a multimeter, check the Mass Air Flow (MAF) Sensor -G70- electrical harness connector terminals to the Motronic Engine Control Module (ECM) -J623- electrical harness connector T94 terminals for an open circuit.

Mass Air Flow (MAF) Sensor -G70- electrical harness connector terminals (ECM) -J623- electrical connector T94 terminals or test box socket / Motronic Engine Control Module

1 / 23
2 / 65
4 / 14
5 / 60




Specified value: 1.5 Ω max.
If the specified value was Not obtained:
– Check the wiring for an open, high resistance or short to ground.
– Check the electrical harness connector for damage, corrosion, loose or broken terminals.
– If necessary, repair the faulty wiring connection.
If no malfunction is detected in the wiring and the voltage supply was OK:
– Replace Mass Air Flow (MAF) Sensor -G70- . Refer to the Repair Manual.
If no malfunction is detected in the wiring and the voltage supply was Not OK:
– Replace the Motronic Engine Control Module (ECM) -J623- . Refer to the Repair Manual.
After the repair work, the following work steps must be performed in the following sequence:
1 - Check the DTC memory. Refer to Diagnostic Mode 03 - Read DTC Memory.
2 - If necessary, erase the DTC memory. Refer to Diagnostic Mode 04 - Erase DTC Memory.
3 - If the DTC memory was erased, generate readiness code. Refer to Readiness Code.

Edited for more clarity + the image of the sensor terminals
 
Last edited:
C

Cryptic19111

Go Kart Champion
That generally is the way to test a maf sensor.. if the car runs better without it, then it's usually bad.
 
mrlapou

mrlapou

Ready to race!
ViRtUaLheretic

ViRtUaLheretic

╭∩╮（︶__︶&#6
first thing Id do is double check yoru intake piping and charge piping.
 
S

SoCalMK6GTI

Ready to race!
Similar issues but g/s reads 2.44 at idle. Swapped all coilpacks with an old set and I thought it fixed my issue until this morning my idle was revving slightly. Car holds boost like a champ. Any ideas?
 
L

lilfleck

Go Kart Champion
DBESTGTI said:
check the fuel trim, clear the faults, start it up and go to the basic setting for fuel trim and let it idle. See where the fuel trims go and how fast they get there.
Click to expand...

Could you explain what exactly the fuel trims are and what they do? I've heard of people "resetting" their fuel trims. Not sure what this does though.
 
eurocars1

eurocars1

Ready to race!
lilfleck said:
Could you explain what exactly the fuel trims are and what they do? I've heard of people "resetting" their fuel trims. Not sure what this does though.
Click to expand...

fuel trims are a representation of a % of fuel (in terms of injector pulse width) that has to be added or subtracted to maintain the desired afr. For example, if your long term fuel trim is +10%, the ecu is adding 10% more time to the injection pulse to give the correct afr on average. Short term trims are more of an "instant" representation of how much time the ecu is adding to the pulse width in that moment.

When fuel trims are "reset", such as when clearing out fault codes, the ecu resets all trim values back to zero and relearns the trims.
 
L

lilfleck

Go Kart Champion
Ah, I see.. so in what other scenarios would you want to reset the fuel trims and/or ECU? And how exactly do you do this? In vagcom I've seen clear codes... but if you don't have any, does it reset fuel trims?
 
You must log in or register to reply here.
Top