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Spark plugs fail in slow traffic


Morning everyone.
Spark plugs failed on me again this weekend, was suck in a huge traffic jam for almost an hour/moving alittle no more than 5mph 1st gear.
Its the 3rd time this year they have gone, all when stuck in traffic for a long time.

The engine warning light comes on, kind of goes in to a limp mode but this weekend I noticed a bit of smoke coming out of the exhaust shortly before it happened.

Got the aa out and they confirmed spark plug 3 had a misfire, he took a look and saw it had a coating of oil on it, cleaned it up and now its running smoothly again. He thinks I may have had a faulty ignition coil installed a few months back.

Before I take it to the garage anyone shed any light on this and back up aa theory? its coming up to MOT time and tbh if its a huge expensive job I’m thinking of getting its through its MOT and part ex, its starting to get a lot of problems recently, wiper motor gone, igniton cylinder replacing, power steering went, all sorted now but this engine one is causing me the most concern.

Cheers everyone.

Year? Miles? Which engine?

If your spark plugs are frequently being fouled by oil deposits, that would suggest an engine with severe wear issues. However, without knowing the vehicle’s model year, the odometer mileage, and maintenance history, this is just my best guess via cyberspace.

Also…how much oil do you have to add periodically, and how many miles do you typically drive before having to add that oil?

I concur, oil fouling is not a coil problem, its a ring or valve seal problem. Either would be expensive on any engine in this A3

How often do you need to add oil? How many miles on it?

An additional thought for the OP to consider:
If your engine is consuming as much oil as Mustangman and I believe it to be, the next problem on the horizon will be a failing catalytic converter. If you have to overhaul the engine and replace the catalytic converter, you will be looking at a very large repair bill.

its 1.6 2006 a3.

As far as oil goes I’m not noticing anything out of the ordinary when having to top up, its not going through oil at all.

This is the 3rd time in almost 12 months, ive done a lot of driving in it this year and its done about 84,000 on the clock.

Did you ask your mechanic why the plug(s) are oil fouling? Don’t know if 06 A3 has cop or coil bank? Single coil? Change it. Coil bank? Hmm maybe more money but it won’t kill you to do it. Why didn’t you do it when he changed the plug?

VW/Audi engines were known to have coil problems. I also would have the compression checked.

it was the aa recovery guy, I had a new coil fitted about 4 months ago, he said in his experience he believes I may have had a dodgy coil fitted and that’s why its happening.

Are compressions checked in MOT?

By MOT I suspect you are in Great Britain. I don’t think there are any England based regulars here. Shouldn’t the MOT web site list what is checked and what it takes to pass or fail? Also not sure what an aa recovery guy is, but you may need to find an actual shop for help passing the MOT.

AA = Alcoholics Anonymous, not clear what that means.
do you mean AAA (American Automobile Association) ?

You may have a fuel problem. Oil isn’t the only thing that fouls spark plugs. A rich fuel mixture will leave so much carbon on the insulators that the plugs fail to fire. A rich fuel air mixture makes black smoke, oil makes gray or white smoke.

it was a white smoke when I saw it.
AA is our roadside recovery here in the uk, you pay £8 per month and they come to roadside or your house if you have any breakdowns or issues, if they cant fix it then they tow you tot he garage if needs be.

I will get its MOT done and get it part ex I think although the coil is still under warranty maybe it would be an idea for them to check it 1st?

I always suggest a compression check just to make sure there is not a serious mechanical issue being the root cause.

Low compression mean incomplete combustion which can foul spark plugs and lead to plug fouling and coil failure.

At least with a compression test you will know whether to rest easy or start sweating… :frowning:

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In the UK they drop the first A so the auto club is AA.

Try installing spark plugs with a slightly higher heat range.

This article explains it.


I should have caught that. However, I think it is the responsibility of the poster to explain any abbreviations used.

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Yeah, AAA is the American Automobile Association. I worked for them in my youth. We had no offices in the UK.

If I had that problem on my Corolla first thing I’d do is remove the spark plug wire, connect a spare spark plug to it, ground the base of the plug against an engine ground, and have a helper crank the engine while I visually checked for a healthy spark. I presume that same thing can be done with the coil on plug design. I’d compare the quality of the spark on the questionable cylinder vs one that doesn’t foul. Shops have various ways to do this too, often using a lab o’scope. I think however you do it, that is priority number one, focus your shop on figuring out if you have a good healthy spark at that spark plug tip or not. After you know the answer to that, folk’s here will probably know what to do next.