2009 Audi A4 2.0T

Mileage: 315,064


UPDATE 6-2-2024
WOULD NOT START
I have been starting it weekly as it's been sitting by the road for sale, and today it decided it would not start. 
I have not done any troubleshooting to determine a cause. 

Everything below here documents my troubleshooting efforts to determine the cause of a cylinder 1 misfire, which 
is still inconclusive. 

And some mentions of other maintenance work I've done over the years. 


Primary Fault Codes:

P0301: Cylinder 1 Misfire Detected

P130A: Cylinder Disabling

P0300: Random/Multiple Cylinder Misfire Detected

 

Secondary Fault Codes:

P0299: Boost Pressure Control Range Not Reached

02115: Front Right and Rear Left Passenger Doors Fail to Power Lock

02616/02615: Fuel Tank Cap Unlock/Lock Open or Short to Ground

02558/02559/00417/00418: Multiple Speakers Open Circuit


Slow coolant leak from water pump region. 

I have had two OEM plastic water pump failures at the gasket interface.

An aftermarket aluminum body pump is currently installed.   


Additional Information:

Winter tires currently installed on vehicle; second set of wheels included with all-season tires installed

Winter tires purchased Feb. 10, 2023, BRIDGESTONE BLIZZAK 225/50R17 94H

All-Season tires purchased June 4, 2021, MICHELIN DEFENDER T+H 225/50R17 94H

All wheel bearings have been replaced sporadically in the last 120,000 miles.  


Scan tool included, software not transferrable, see https://www.ross-tech.com/ for information

 

Oil changed Feb. 24, 2024

New fuel injectors installed March 16, 2024 (along with new serpentine belt and air filter)

 

Engine Compression Test (Dry):

 

Compression Pressure Specification from Service Manual

New

159.5 to 203 psi

Wear Limit

101.5 psi

Maximum Difference Between Cylinders

43.5 psi

Cylinder 1:           136psi

Cylinder 2:           134psi

Cylinder 3:           138psi

Cylinder 4:           134psi

 

2009 Audi A4 2.0T – Additional Diagnostic Information

 

Misfire isolated to cylinder 1 using live misfire count data. Almost zero misfires registered at start-up idle or free rev. Misfire issue manifests when vehicle under acceleration load or at high free rev (3500+).

Update: Misfire also manifested after several minutes of 800rpm idle. (Warm engine?)

After misfires registered, ECM disables cylinder 1.

Cylinders 2, 3, and 4 continue to register zero misfires.

 

Coil Packs and Spark Plugs:

Swapped between Cylinders 1 and 2 and 1 and 4. Misfire stays with cylinder 1.

Confirmed spark signal is present at all coil pack connectors (at least at engine start).

Confirmed 12v power present at all coil packs.

No specific fault codes.

 

Fuel injectors and/or fuel delivery:

Fuel injectors replaced at onset of multiple/random misfires.

Confirmed cylinder 1 injector functions and wiring harness is intact.

Confirmed injector control signals are present at harness connector (at least at engine start).

LEDs were used to detect signal presence so sufficient electrical current is unconfirmed.

No specific fault codes.


Valvetrain:

No specific fault codes.

Collapsed/failed lifter (hydraulic lash adjuster)?

Perhaps 1 of 2 intake or exhaust valves in not opening fully.

Possible issue. Requires further investigation.


Engine Control Module (ECM):

No specific fault codes.

Possible issue. Requires further investigation.

 

Coil pack wiring harness:

Inspected and appears intact.

No specific fault codes.

Likely not the issue.