EVAP leak and Misfiring.. codes 16840/16684/16685.. help!?!?!..

[fritzner]

the car/mods:
'05 1.8T A4 6spd 70k miles
REVO-II with TT injectors
stock airbox, exhaust, IC


here are the codes:
Address 01: Engine Labels: 06B-909-518-AMB.lbl
Control Module Part Number: 8E0 909 518 BC HW: 8E0 909 018 A
Component and/or Version: 1.8L R4/5VT G 0010
Software Coding: 0016711
Work Shop Code: WSC 14647 026 468711
VCID: 72E0134D143F
3 Faults Found:

16840 - EVAP System: Very Small Leak Detected
P0456 - 001 - Upper Limit Exceeded - Intermittent
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 - Upper Limit Exceeded - Intermittent
16685 - Cylinder 1: Misfire Detected
P0301 - 001 - Upper Limit Exceeded - Intermittent

my thoughts:
i was thinking coilpacks at 1st, but interestingly, it seems to run just fine if driven gently.. its only when i get into the boost a bit that it misfires.. if i back off right away, it stops misfiring, and the MIL doesnt come on.. if i stay on it for just a second, the MIL starts flashing.. i am wondering if it is more of an injector issue or something like that..


the ross-tech wiki says:

16840/P0456/001110 - EVAP System: Very Small Leak Detected
Possible Symptoms

Malfunction Indicator Light (MIL) active

Possible Causes

Fuel Cap not fully attached
Evaporative Emission (EVAP) System leaking/faulty

Possible Solutions

Check Fuel Cap
Check Evaporative Emission (EVAP) System

Special Notes

On 2006 and 2007 Passat, check fuel cap part number. Updated version ends in "G". Please refer to Technical Bulletin 2016757 for details.

16684/P0300/000768 - Random/Multiple Cylinder Misfire Detected
Possible Causes

Air Intake System leaking
Fuel Supply faulty
Injector(s) faulty
Ignition Cable(s) and/or Spark Plug(s) faulty
Ignition Coil(s) faulty
Exhaust Gas Recirculation (EGR) Valve (N18) stuck/open
Camshaft Position Sensor (G40) faulty

Possible Solutions

Check Misfire Recognition
Check Air Intake System
Check Fuel Supply
Check Injector(s) and Injector Sealing
Check Ignition Cable(s) and Spark Plug(s)
Check Ignition Coil(s)
Check Exhaust Gas Recirculation (EGR) Valve (N18)
Check Camshaft Position Sensor (G40)

Special Notes

This DTC indicates that one or multiple cylinders are misfiring, but the ECU fails to identify the cylinder.


16685/P0301/000769 - Cylinder 1 Misfire Detected
Possible Causes

Ignition system
Fuel injectors
Fuel pressure
Running out of fuel
EVAP canister purge valve
Evaporative emission system
Low compression
Base engine problems
Controle Module damaged

[fritzner]

i have been told if it is a clogged injector, i should get a lean code.. leaking injector seal was also suggested, not sure if that would cause a lean code.. someone said a clogged fuel filter..

what about just bad plugs??..

maybe i will replace the fuel filter, put in the new upgrade DV i never installed, put in new plugs and check the injector seals.. then see how it runs..

[diagnosticator]

When a coil pack has partially failed, it is consistent with the symptoms you describe. When the car is driven gently, the throttle is not opened a lot, so the cylinder pressure is low at the ignition spark point. With lower range cylinder pressures, the voltage required to cause the spark to jump the plug gap is also low compared to when the cylinder pressure is a lot higher, increasing as the throttle is opened further, especially when boosted charge air pressure exists. Higher throttle opening angles require a lot higher secondary voltage output from the coil pack to cause the spark to jump the plug gap. A faulty coil pack can't achieve the necessary higher output voltage required with higher cylinder pressures at the spark point. This is why the symptom of misfires is not noticeable when the car is driven with a light accelerator application, then starts to misfire when the throttle opening angle increases and the engine load is higher, compared to when the throttle is opened only a small amount.

It is also possible (but very unlikely compared to a faulty coil pack, ) for an injector to be clogged, and flow restricted, that results in a lean mixture misfire in the effected cylinder.

In order to isolate the cause of the misfires, if one or two cylinders are experiencing misfires consistently, according to the DTCs stored, swap the misfiring cylinder coil pack with one of the cylinders that is not misfiring, then clear the fault codes, and test drive the car, If the misfiring cylinder changes with the moved coil pack/s then that confirms the coil pack is bad.

If it is a lean mixture misfire, due to a clogged fuel injector, then the misfiring cylinder# won't change with the moved coil pack. The chance for both defects to exist at the same time in the same cylinder is greater than zero, but as a practical matter, is so small, it's not relevant.

[fritzner]

thank you SO much.. this is awesome information..

though i already have the "R" coilpacks, the service manager at my local garage said my vehicle was eligible for the free coilpack replacement campaign.. i am schedule for 7:30am tomorrow..

hope it works!

[fritzner]

new coilpacks did the trick.. and they were free!!..

the radio flyer is running great again..

your response is much appreciated diagnosticator..

[diagnosticator]

You are welcome, thanks for the update!

[jaustin]

Is it still possible to get audi to cover the coil packs? I never received my letter.

[fritzner]

Is it still possible to get audi to cover the coil packs? I never received my letter.

I just had all 4 coilpacks replaced at the dealership over the summer.. completely free of charge.. with no letter.. your results may vary, i am just saying what happened to me..