My 97 A4 1.8T Qauttro is starting to give problem.

Im getting codes for Cylinder 2 and 4 misfiring. I plan on replacing all the Spark plugs because its time for that any way.

However I'm thinking that it may be more than that base on what I've read and seen.

If I have to replace the ICU on the air box, I have read mixed reviews if I should, or have to replace the coils with it?.

Also anyone ever used the Bosch 7402 plugs? I just ask because they are way cheap.

This probably will turn into a more of an engine make-over.. so if I do the plugs, and the ICU, and if I have to do the Coils, then im just going to do the wires too.

 

Try swapping the coils and see if the misfires follow the coil packs. It could just be the 2 packs going bad at the same time, and you should just replace all 4.

If the misfires don't move, or are random, its most likely the ICM. You wouldn't have to replace the coil packs but it can't hurt.

 

The oldest 1.8 that I have had was a 99 but it had the coil packs that sit on the plus so there are no "plug wires." I think yours should be the same way.

 

^^^ correct, these cars are coil-on-plug ignition.

 

Trouble shooting with the least expensive route first will most likely save you some $$. Replacing the plugs is always a good starting point. Make sure they are gapped to spec. Something as simple as this can be often neglected, which then leads to problems. Then I'd say to look into checking the coil packs and lastly the ICM.