Ignition coils

Hey there!

I own an audi a3 quattro 1.8t 2000 model. So about a month ago I had trouble, my engine was misfiring and my mechanic attributed it to my ignition coils. When i went home i swapped out the coils from an audi tt 225. It seemed to be working fine for about a month but now it's misfiring again. My mechanic says it's due to the fact that the coils are different and due to the empty space left, won't work properly. But when i looked online for some after market coils for my car they resemble the tt225 coils more than my ones. So i figured I'd just go to the audi dealership but they are almost twice as expensive .

So is it true that the 225 coils (which are pretty much the same as the s3's) won't work on my engine? It does make sense to me that they wouldn't but what has me wonderig si the fact that they worksed at first and now they just don't anymore , and I'm pretty sure they didn't break that quickly .

Also, is it bad for me to be driving the car in this state? It vibrates slightly when i drive it normally, the more i put my foot down the more it shakes.

<tuffty/> said:

Coil packs will work fine apart from not being supported in the cam cover... bolt down coils as you know have a square holes in the cam cover... push in coils have a round hole the secures the packs... electrically they will function fine..

There is no such thing as '225' coils as all 1.8t's from AUM to BAM uses the same packs.. as do the earlier bolt down yours originally came with... AGU are the only ones that won't work...

Have you scanned for fault codes?... are the '225' coils new or secondhand?

<tuffty/>

Click to expand...

The coils from the tt 225 are the ones that just plug in as the ones i originally had are bolted down. I also noticed when put next to eachother the coils from the tt are slightly longer. I reffer to them as 225 coils as i got them second hand off of a tt 225. I haven't scanned for fault codes as my mechanic was busy but i will do this tomorrow. I noticed the holes in the BAM block where the coils plug into are slightly different than the ones in my car, and that's what i attributed the fault to. They fit in fine into my block but it seems there is a larger gap. But as i was saying it doesnt make sense to me that they'd work at first and then start messing up.

Am i safe to drive the car without risking any further damage?

Edit:
Something that's been happening recently is that my car sometimes give me difficulty when i ignite it and when I'm driving and i come to a stop the rpm would go down below 700 and back up a few times and I'd hear the engine making noise. I don't know if this is linked or something entirely different .

Thanks for the help