Multiple Cylinder Misfire

[Dakota_Ice]

Where to start?

1999 Audi A4 Avant, 1.8T 85,000 miles. Blinking check engine light, than solid. Able to drive car home. Vag-com codes 16685 thru 16688 which identifies all 4 cylinders having a misfire. Timing chain replaced at 70,000 miles.

Because all of the misfires occurred simultaneously, I doubt it is plugs or wires. Coilpacks? Other?

[Nevr]

id start with the coils. are yours recalled?

timing chain? 4 cylinder? 99 audi a4? does not compute.

[Dakota_Ice]

Edited original post, 1.8T engine. I wanted to preempt someone asking if the timing belt/chain was replaced. No recalls on this vehicle, as it was the first thing I checked due to bad coils on many VAG cars.

[Die Frau]

Sounds like coils are a good place to start.

With the car idling unplug one at a time. If the idle gets worse, that coil is good. If it does not change, that coil is not firing.

You can also test coils with a screw driver and a helper, but it is tricky. Car off. Pull coil off of spark plug but leave plugged into harness. Place a screw driver into the coil, but not touching the sides. Hold both coil and screw driver, but be sure to not touch any metal. Have helper start car. A good coil will spark between the screw driver shaft and the outer metal coil shroud. A bad coil will just pop.

Other than that, it could be the ECU, the harness or bad plugs.

[Kunkel]

What is measured value #32? If it is not 0 +/- 10 it might be a HUGE vacuum leak.

[colandr3]

Power stage? I know 99 passats had them, not sure about A4's.

[thepartsguy]

dont rule out bad gas.......just sayin

[Asick6]

Ignition Control Module

[Dakota_Ice]

I cleared the codes and logged the following on a short drive. Ran fine for about 3 minutes, than started missing with a flashing check engine light that went to solid after 15 seconds.

At Idle in Driveway:
Address 01: Engine (8D0 907 557 P)
15:22:58 Group 001: General Engine Data
880 /min Engine Speed
76.5°C Coolant Temperature
1.6 % O2 Sensor Control
111110 Adjustment Conditions
15:22:58 Group 026: Knock Sensor Voltage (Including Amplifier Factor)
0.471 V Knock Sensor Voltage Cyl 1
0.314 V Knock Sensor Voltage Cyl 2
0.471 V Knock Sensor Voltage Cyl 3
0.628 V Knock Sensor Voltage Cyl 4
15:22:58 Group 032: Oxygen Sensor Before TWC Learning (Max.) Values
3.1 % O2 Sens Learning Val@Idle
0.0 % O2 Sens Learning Val@Part Ld
_
_

Minimum and Maximum values logged during drive:

Block 001 O2 Sensor Control % = Min -14.1, Max 12.5
Block 026 Knock Sensor 4 Voltage = Min .785, Max 13.188
Block 032 O2 Sensor @ Idle = Constant 3.1
Block 032 O2 Sensor @ Partial Load = Min 0.0 to 1.6

Return trip logged the following, running very bad:

Block 003 Air Mass Flow g/s = Min 1.87, Max 55.76
Block 033 O2 Sensor Voltage = Min 0.0, Max .87
Block 033 O2 Sensor Before TWC = Min -5.5, Max 29.7

Fault Codes after drive:

Address 01: Engine Labels: 058-907-55x-AEBN.lbl
Control Module Part Number: 8D0 907 557 P
Component and/or Version: 1.8L R4/5VT MOTR HS D04
Software Coding: 06201
Work Shop Code: WSC 06325
VCID: 3D7AB7C01D19
5 Faults Found:
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -
16685 - Cylinder 1: Misfire Detected
P0301 - 35-00 - -
16688 - Cylinder 4: Misfire Detected
P0304 - 35-00 - -
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -
16685 - Cylinder 1: Misfire Detected
P0301 - 35-00 - -
Readiness: 0010 0101

[Dakota_Ice]

Checked the resistance of the Ignition Control Module and all 4 pins were at 2.47 million ohms. I understand that the tolerance is between 2.0 and 3.0 million, so this is not the problem. Thanks for the tip!

[Dakota_Ice]

My daughter said she last filled up at Holiday and she has about 2/3 of a tank left (approximately 150 miles of driving on this gas).

[Nevr]

Sounds like coils are a good place to start.

With the car idling unplug one at a time. If the idle gets worse, that coil is good. If it does not change, that coil is not firing.

You can also test coils with a screw driver and a helper, but it is tricky. Car off. Pull coil off of spark plug but leave plugged into harness. Place a screw driver into the coil, but not touching the sides. Hold both coil and screw driver, but be sure to not touch any metal. Have helper start car. A good coil will spark between the screw driver shaft and the outer metal coil shroud. A bad coil will just pop.

Other than that, it could be the ECU, the harness or bad plugs.

just for reference, a friend has a 1.8t in a b6 a4, we were trouble shooting a misfire/surging under boost, we changed the plugs, swaped and messed around with some diverter valves, maf, and other various things, to no avail. we also tried the plug/unplug coil thing, as he has had one blow before, and we did it that way to diagnose it, no difference in idle or anything unusual, as the miss was only in boost, not at idle. brought it in to carousel, and they replaced all for coils under recall... problem solved. so while it was the coils causing the problem, the old plug in and out trick left us with no clue where to look next.

op: i would replace the coils.

[Dakota_Ice]

I finally found my tools to take off the coil packs. Starting with the number one cylinder, this is what I found. I could not believe that the spark plug came out WITH the coil pack



There were also numerous cracks in this coil pack:


The threads on this spark plug were not damaged or worn, so I can only assume that the plug was never tighten or worked itself loose. I decided to order 4 new coil packs and replace the plugs and hope that will solve the problem.

Have to love German cars!

[Die Frau]

Yeah. I think that would do it. It is not always the problem, but the coils are always the first thing I check on a 1.8T

[colandr3]

holy crap that plug really ripped that boot up.