Checking for faulty ignition coils

[mattk]

Firstly hi chaps, this is my first post, i've not owned my audi (a4 1.8t) for long so it's a very new car to me.

It has, what feels like, a misfire. It judders at low revs under load and generally has no power.

So this weekend I plan to replace the spark plugs and check the ignition coils. Is there a way to tell whether an ignition coil is faulty just by looking at it?

I do have code reader that should have arrived in todays post, but having never used one before i only planned on using it as a guide.

Thanks in advance

Matt

[matta4]

No you cant really tell by looking. When you get your code reader you will possibly get a code for misfire cylinder 1,2,3,or 4 number 1 is the cam pulley end if you dont have a misfire code you can check the resistance on the coil the middle terminal is the earth check the resistance between the outer 2 terminals it should be 0.4-0.6 ohms

[mattk]

Thank you for the advice on how to check the coils individually.

I took each coil out of the engine to test them and they all registered 0.00 when the multi meter had settled. I did this for every sensitivity setting, and they all read 0.

Does this mean every coil is faulty?

Thanks again
Matt

[matta4]

I wouldnt think all 4 would be faulty at the same time although we replace all 4 at work if one goes down. Are you checking resistance correctly the meter needs to be set to this symbol Ω put the leads to the outer terminals to check.Have you plugged your scanner in yet ?

[mattk]

The scanner they sent doesnt fit, and i won't get a replacement until next week.

The meter is set to the Ω position, i have tried it in every setting from 2000k to 200 and each one reads 0 on every coil. I am definatley only touching the outer two terminals.

The coils do seem quite old, the rubber boots that fit over the spark plugs are perished on some of them.

I've just run the car again and the readings are the same when hot. Infact i'd say it even idles worse now with the new spark plugs fitted, which seems strange.

[matta4]

Does sound like coil pack problem if its worse now you have disturbed them.does the car noticably misfire under load or do you just have rough idle?

[mattk]

Both really. It misfires under load pretty badly but gets less noticable as the revs get higher.

Oh and to add to an already frustrating weekend, the central locking now won't work after i disconnected the battery!

[rickfr]

Check the small HT leads from the coil pack, I had one that had been slit for some reason and had not been resealed. It caused the lead to arc out to the surrounding metal work causing a similar problem to yours, much to my relief, replaced the HT leads and hey presto, job done. A prior and worse case problem I had again very similar had me thinking along the same route, changed the plugs, no joy, eventually gave it to Audi to look at and after a compression test found a valve burnt out. If the new plugs don't work or my hopefull solution get a compression test done, I hope that it is not the same as I had because it will be expensive to fix. Good luck.

[mattk]

Thanks for the advice guys, today's job is to check all the wires and connections, and see if anything is amiss.

Cheers
Matt