Sloooo4esT

do i need to disconnect the battery and reset the ecu or will it adjust itself? gonna clear code wednesday and cross fingers it does not come back, or else...???

SCarGo02

...but it didn't do much if anything.

Joey T

How did you decide it was a bad MAF?

Sloooo4esT

mixture adaption not reached, possible MAF.

pulled o2 sensor, its white, but mpgs dropped down far

my next guess is swap out coils???

5000ish rpm car gets a boost of energy

feels slow like boost leak but boost holds

once in a while the car runs fine

Joey T

1. Fuel pressure too low.

What is your fuel pressure?

2.Misfires. Is it skipping at all?


3. MAF. MAF is your last choice.



Checking MAF: WHEN LOOKING AT CONNECTOR ON HARNESS, WITH METAL CLIP UP, ONE IS ON LEFT AND SIX IS ON RIGHT.

WARNING!
DO NOT touch the hot wire element in the Mass Air Flow sensor .

* For functional testing of the Mass Air Flow (MAF ) sensor, also see On-Board Diagnostics With Scan Tool VAG 1551, "Basic Setting" function 04. See: Computers and Control Systems\Testing and Inspection\Scan Tool Testing and Procedures\Scan Tool Testing\Basic Setting (Function 04)

Test condition.

* Circuit breaker S72 - OK.

CAUTION :
Wait 30 seconds after switching OFF the ignition BEFORE disconnecting the Engine Control Module (ECM ) harness connector.

Checking ground circuit

* Ignition switched OFF.
* Disconnect harness connector from MAF sensor.

6-Pin Connector


* Connect US 1115 LED tester or equivalent between harness connector terminal 1 and remote positive cable connection.
* LED tester must light up.

If not:

* Locate and repair open in ground circuit, using wiring diagram.

Checking power supply from ECM

* Connect LED tester between MAF sensor terminal 5 and engine Ground (GND).
* Switch ignition ON.
* LED tester must light up.

If not:

* Switch ignition OFF.
* Connect VAG 1598 test box with VAG 1598/5 adapter harness to engine wiring harness. Refer to VAG 1598 Pin Out Box Connecting. See: Computers and Control Systems\Testing and Inspection\Scan Tool Testing and Procedures\Scan Tool Testing\Scan Tool Connecting and Initial Checks\Connecting and Testing VAG 1598 Pin Out Box
* Connect LED tester between terminal 19 (GND), and terminal 37 of Test Box.
* Switch ignition ON.
* LED tester must light up.

If Yes:

Engine Control Module Harness Connector


6-Pin Connector


* Locate and repair open in circuit between terminal 37 of ECM harness connector, and terminal 5 of MAF sensor connector.

If not:

* Replace ECM.

Checking power supply from the Fuel Pump relay

* Connect LED tester between MAF sensor terminal 5 and engine Ground (GND).
* Switch ignition ON and operate starter for a few seconds.
* LED tester must light up when ignition is switched ON and during starter operation.

If LED tester goes out during starter operation:

* Verify that injector valve circuit breaker - S72 is OK.
* Check continuity between: terminal 5 of sensor connector, and injector valve circuit breaker - S72, using wiring diagram.
* Must be 0.5 ohm maximum.

Central Electric Panel With Detail Of Relay Position 6


* Check continuity between: injector valve circuit breaker - S72 and terminal 31 of fuel pump relay - J17, relay location 6, using wiring diagram.
* Must be 0.5 ohm maximum.
* Check fuel pump relay and if necessary, check control signal to fuel pump relay.

Checking MAF sensor wiring

* Connect VAG 1598 test box with VAG 1598/5 adapter harness to engine wiring harness. Refer to VAG 1598 Pin Out Box Connecting See: Computers and Control Systems\Testing and Inspection\Scan Tool Testing and Procedures\Scan Tool Testing\Scan Tool Connecting and Initial Checks\Connecting and Testing VAG 1598 Pin Out Box
* ECM remains disconnected.
* Disconnect MAF sensor harness connector.
* Using wiring diagram, check following circuits for continuity or shorts, by testing at terminals indicated:
* MAF harness connector terminal number 2 to test box socket number 26.
* MAF harness connector terminal number 3 to test box socket number 7.
* MAF harness connector terminal number 4 to test box socket number 25.
* Must be 1.0 ohms maximum.
* Repair open or short circuits as necessary, using wiring diagram.

Note : Use only gold replacement terminals when making repairs to MAF sensor connector.

Checking MAF sensor function

Internal resistance check.

* Disconnect MAF sensor harness connector.
* Switch DVOM to 200 ohm range.
* Connect multimeter (using VW 1594 connector test kit) to MAF sensor terminals 1 and 2.
* Record resistance value.
* Disconnect test leads from MAF sensor, and connect test leads together.
* Display value must equal value recorded previously.

If difference is greater than 0.1 ohm :

* Replace MAF sensor.

Output signal check.

* Re-connect MAF sensor harness connector.

Mass Air Flow Sensor Connection


* Peel back rubber boot on back of harness connector to expose terminals.
* Switch multimeter to 20 Volt range.
* Connect multimeter to (exposed) terminals 1 and 3.
* Switch ignition ON.
* Must be 1.2 - 1.5 Volts .
* Start engine and let idle.
* Must be approx. 2.5 Volts .
* Increase Engine Speed (RPM) briefly.
* Voltage must increase to 3.0 - 5.0 Volts
* All of the specified voltages must be obtained.

If not:

* Replace MAF sensor.

Checking MAF sensor burn-off

Note : The sensing element of the MAF sensor must be clean to function properly. To accomplish this, the element is heated to 100°C (183°F) for one second, each time the ignition is switched OFF.

Burn-off occurs only under the following conditions:

* Engine Coolant Temperature (ECT) above 60°C (140°F) .
* Engine Speed (RPM) has exceeded 2000 rpm for at least 3 seconds .
* MAF sensor wiring is OK.
* Injector valve circuit breaker S72 is OK.
* Disconnect MAF sensor from air cleaner housing and position far enough back so that burn-off process can be observed.

Note : Do not disconnect the intake air hose or the MAF sensor connector.

* Start engine and let idle above 2000 RPM for minimum of 3 seconds .
* Switch ignition OFF.
* Observe burn-off process.
* Heating wire glows for about 1 second.

If NO:

* Position aside rubber sleeve on MAF sensor connector.
* Connector must remain connected to MAF sensor Connect US 1115 LED tester or equivalent to terminals 1 and 4.
* Repeat test sequence.
* LED tester must light up during burn-off.

If LED tester lights up:

* Replace MAF sensor.

If LED tester does NOT light up:

* Connect VAG 1598 test box with VAG 1598/5 adapter harness to engine wiring harness. Refer to VAG 1598 Pin Out Box Connecting. See: Computers and Control Systems\Testing and Inspection\Scan Tool Testing and Procedures\Scan Tool Testing\Scan Tool Connecting and Initial Checks\Connecting and Testing VAG 1598 Pin Out Box
* Connect LED tester to terminal 26 (GND) and terminal 25.
* Repeat test sequence and observe LED tester.
* LED tester must light up during burn-off.

If LED tester does NOT light up:

* Replace ECM.

If LED tester lights up:

* Check for continuity (and also shorts to GND), between: terminal 4 of MAF sensor connector, and terminal 25 of test box.
* Resistance must be 0.5 ohm maximum.
* Locate and repair, as necessary, shorts/opens in circuit wiring between MAF sensor connector terminal 4, and ECM terminal 25.

TabulaRasa

2nd.

Sloooo4esT

what else can I be looking at here

failing coil?

o2 sensor is white

have hesitation but not violent, nothing at all like failing POS felt like
perhaps I need to stop thinking to myself I can diagnose and fix it and drop it at the shop. but they assume it's MAF, I kinda disagree with y nearly useless knowledge on engineering

TabulaRasa

The symptoms lasted a whole 1 day before I replaced it with a MAF out of a 1991 Audi 200 20v. The change was instant.

Boost leaks were tested for, none found. 5 new spark plugs were installed.

I was in a hurry to fix it because I was a week away from attending a track event at Mid America Motorplex in Pacific Junction, Iowa with the ACNA.

SilberUrS6

Sometimes they get silica deposits that make them not work as well.

It is a relatively cheap and easy fix. And they do need to be replaced periodically.