[A4] 97 A4 2.8l V6 AFC code, No start, No spark, No DTCs

Pbadore at aol.com Pbadore at aol.com
Fri Dec 14 19:25:13 PST 2007

The 2.8l V6 with engine codes AFC (A4 and A6) or the earlier code AAH 2.8 V6 
engines can be checked for secondary circuit resistance by pulling each pair 
of spark plugs wires off at the coil pack.
The coil pack stays on the engine connected to the primary side circuits. The 
first coil fires cylinder 1 and 6, the second coil fires 2 and 4 and the 
third fires 3 and 5. With the spark plug wires off at each coil the VOM should be 
placed on the ohm meter function and the each end of the positive and negative 
probes should touch inside the coil pack towers. The A4 factory shop manual 
specifies a resistance range of 9K to 14K ohms. Check each coil pack 
separately. On the two used A6 coil packs that I used for trouble shooting the coil 
terminals were bright and clean and all read 11k ohms exactly. On my bad A4 no 
spark, no DTCs car the third coil had a small crack in the coil tower and a 
corroded number 3 cylinder terminal pin. That A4 had a very hard to start condition 
until it finally refused to start at all.
The car's owner thought the hard staring was due to the almost 190,000 miles 
showing on the odometer, but after changing the coil pack, new spark plugs and 
wires the A4 started within 1 second of being cranked. If the spark plug 
wires are original Bremi made wires the date codes are visible at the end of the 
metal shroud for each spark plug wire as a 2 digit week and year code. On this 
A4 the code was 48 96 for the 48th week of 1996 which indicated that the wires 
had seen almost 190,000 miles of service. Also, the Bremi wires are easy to 
twist off the spark plugs with the Bremi spark plug wire special tool. The 
number 3 cylinder wire is the most often damaged due to the difficulty of reaching 
the wire end without the special tool. This car had one replacement spark 
plug wire for number three cylinder.   The other suspect part   in the 12V V6 
ignition system is the power output stage. The A4 output stage is located on the 
air box and on the A6/100 is mounted to the dash panel. A failure in the 
output stage would take out two cylinders at a time since the coil pack is a waste 
spark design that fires pairs of cylinder together. On an A4 1.8l turbo AEB 
code engine this part has a very high failure rate due in part, I believe, to 
its location near the turbocharger/catayst exhaust heat--I have had two fail at 
low miles on other A4s in my family.         

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