Starting and misfire issues

[Don_with_a_audi]

Hi guys, I've been through so many pages looking for threads but can't find help.

I have a 2.0 b6 and I started having cold start issues a while back and after a lot of digging I figured out it was the water temp sensor so I replaced that and everything was great. 3 months later, so 2 weeks ago it started again and also started running really bad, like it was only running on 2 cylinders.

I took it in and had diagnostics done. They didn't pick up anything on the diagnostics after clearing the 100 misfire codes and rerunning it. Only thing was a throttle body alignment code which is very weird. They took out the spark plugs and saw one wasn't burning. Said it's either the plugs or coils.

I proceeded to replace all the spark plugs and everything was fine again except for the cold start issue... For about a week.

I took out the plugs again and they all look different.. 2 had quite a bit of oil around the thread and they look like they might not be burning either.

I can't afford to just replace the coils and hope for the best,

So 2 questions, why would it be struggling to start while cold so soon after fixing that issue,
And 2, what would be the cause of the misfiring if it's not the spark plugs? Coils, fuel line, wiring?

All help would be appreciated

Thanks

[Don_with_a_audi]

Wanted to add pics of the spark plugs but couldn't figure out how

[eljay]

Did the codes indicate specific cylinders misfiring?
You mentioned that 2 plugs look like they are not burning. Can you reproduce the problem on another cylinder by moving a coil to that cylinder? When you move a coil, do the codes now indicate misfire on a different cylinder?

Some more info on how to check ignition coils: http://www.ebay.com/gds/How-to-Test-...tml?rmvSB=true

[f0reignfeatures]

I personally would replace the coils from what it sounds like.

Audi of America issued a recall for the B6 and the previous owner of my car actually had them replaced for free. I know your overseas, so I'm not sure if that applies, but if not you can look for a set of lightly used coil packs and/or swap them around to see if there are changes. They can be found for cheap. If I recall correctly, Audi suggests replacing them every 40-50 thousand miles regardless.

Take some time to listen to the motor with the hood open to see if you can hear any hissing as well. This will indicate a vacuum leak. Mine was misfiring on one bank (I have a 3.0) and all it took for it to stop was pushing the connections by the PCV valve/assembly together lightly. Good luck!


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[Don_with_a_audi]

I didn't do the diagnostics so not sure. That's good advice from both of you thank you. I will double check my plugs tomorrow and see then I will swop coils. And see after a week. I'm going to replace my fuel filter as my father thinks a fuel problem could be the cause. Interesting to know about the recall but don't think that happened here. Second hand coils are as rare chicken teeth. I do recall a hissing sound so maybe I should look more inot that. Would that be the cause of the cold start issues?

[f0reignfeatures]

Mine was slightly misfiring on startup every once and a while before I pushed the assembly together. The check engine light would come on and it would throw a misfire code like p0304 (misfire cylinder 4) for example. The car itself didn't feel like it was running poorly though and I'm always very conscious of how the car sounds and feels.

It's too bad the coils are so rare for you to find. Look into the recall, it might not just be a US thing.

My bet would be either a vacuum leak or bad coils. While your fuel filter should be replaced as preventative maintenance, I doubt it would cause misfiring as severe as you're describing, just my opinion though. Keep us posted man!


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[Don_with_a_audi]

I swopped coils and checked again. I have singled out 1 that I think could be causing issues. Next weekend I will buy a new one and see what happens. The cold start issue I have figured out is my water temp sensor thats packed up again cause my temp gauge is stuck at 90*C (optimum running temp). I think it might be a loom/wiring issue cause I replaced that sensor 2 months ago.

[Don_with_a_audi]

Update, I replaced the coil I suspected and it's running like a dream again. Thanks for everyone's input. Just got to see why my temp sensor is screwy again

[Dappa01]

Update, I replaced the coil I suspected and it's running like a dream again. Thanks for everyone's input. Just got to see why my temp sensor is screwy again

Did u install a temp sensor from Audi or aftermarket. I had that bit me before. I installed an aftermarket one and after 2 days had issue. Lost a lot off time chasing my tail.

[Don_with_a_audi]

Aftermarket, thanks, I'll go to Audi then. Got a long list for them haha