Ignition amplifier on pre-facelift 2.8L
 

Hi. Can you tell me where the ignition amplifier can be found on a pre-facelift 2.8 A8. The car has started to tick over abnormally (lumpy rather than surging) and with a misfire detectable when driving at 1000 rpm, particularly up slight inclines (under load). The misfire is not detectable at higher speeds. Also time to start the engine when turning over with the starter motor is now slightly prolonged, although the engine always does start. New spark plugs haven't helped. I would suspect the amplifier rather than the coil pack just from general reliability issues reported on VAG ignition systems using this set up. Thanks for any info on this

Its underneath the coilpack at the front of the engine after the covers have come off. It's part of the coil.

Thanks for the information. Cleaning the terminals on both sides of the unit with a fine file and electrical terminal cleaner (ignition amplifier unit part no 4A0 906 351) hasn't improved the irregular tickover and still detectable misfire at 1000 revs when driving. Shows up as noticable very slight jerkiness on the move at low revs 1000-1200 in town, as well as the tickover irregularity when at standstill. Never cuts out or feels as if it will cut out or not pull away. Not detectable at higher revs and pulls away from this rev level very smoothly with no evident reduction in power or torque; cruising on motorway unaffected. I'll try changing the ignition amplifier.

Have you used VagCom on it yet?

I would recommend having it scanned before spending any money as there are a couple of processes that will help pin down the culprit.

VagCom may tell you which cylinders are misfiring. You can then swap the plugs between cylinders and see if the misfire follows the plugs.

Or you can change HT leads and see if the misfire follows the HT leads. If you don't have VagCom, there should be someone in your area that can help.