S3 missfire after head refit.

[DavidW]

I recently had the timing belt go on my AMK S3. I've now got it all back together but there seems to be a missfire, mostly at low revs seems to clear when at higher revs. I do have the engine light on.
When I got it home I took the oil filler off and a fair amount of smoke escaped. Have I done something severely wrong here, timing out etc, or do you think it could be blocked breather pipes with the build up of smoke in the head cover?

Coilpacks and plugs were fine before belt let go so I think it's unlikely to be them and much more likely to be related to the head being off.

 

[s3dave]

sounds like you may have got the belt a tooth out ...easy mistake

 

[beachbuggy]

Did you remove the head? the title says you did but the post says the cambelt. If you removed the head it could just have oil in the water gallies and vice verse. This would cause the smoke/pressure in the cylinder head. If you have a misfire, could either be a bad coil pack or yes a tooth out but unlikely if it's fine when the revs rise.

Do you have oil in the coolant?

 

[s3dave]

His belt snapped so it was not HG failure, get it on the computer

 

[DavidW]

Yes the head was off. I've refilled the coolant and noticed a small film in there, I assumed that was just because some mixed together in the bottom end when I took the head off, is this possible?

Initially I did have the belt a tooth out but it was never turned over like this, I noticed that when I put the lower belt cover back on that the marks on the pulley were not quite in line so I sorted that. When the revs rise it sounds fine again, it's a noticeable vibration at idle and worse at about 1500, then starts to clear.

I had a bit of white smoke from the exhaust at first but that seems to have cleared as the engine began to warm, it's times like these I really wish I had a laptop and VCDS!

 

[Sandip]

PM me where abouts in Lancs you are David, wouldn't mind having a look at it for you if you want?

Did you get the head pressure tested whilst it was off?

 

[DavidW]

Yes, the head had the bent valves replaced, pressure test and skimmed.

 

[Sandip]

Quick check to see if the head may possibly be cracked is to pour some red food colouring into the expansion tank, run the car for a while, let it tick over if it can, turn the car off and then pull each spark plug out one by one. If the white ceramic is pink you've got coolant getting into the chamber.

Very slim chance this could be the issue but it's a simple check to rule it out

 

[S3 Nattie]

The head shouldnt be cracked if it was pressure tested.

As you got the EML, your likely to have the incorrect correlation fault code. I had it when I put my engine back together, basically the timing is out and the crank and cam are not in sink. Get it on the computer and see what the code is before you do anything else.

 

[DavidW]

Why would the timing be out? I set it up with the marks on the cam cover and bottom belt cover, aswell as manually setting no1 to TDC. I'm not disputing your theory, just wondering why it would be.

 

[S3 Nattie]

I done the same when I done mine and thought it was all aligned right but it was out very slightly and got a incorrect correlation code come up. Did you look at the mark on the gearbox too as I found that was easier to use instead of the crank.

Need to see the fault code you got really as I could be something completely different to the timing etc. Im just going by what happened to me when I did my timing and had a fault code come up straight away.

 

[s3gazz]

i had simler prob when i had my timing belt changed the timing was out after they sorted it light went off but did not have no smoke pal

 

[DavidW]

I think the smoke was probably just a bit of oil and water that had mixed together when the head came off, it's the lumpy idle and engine light that's really bothering me.

Where is the gearbox mark, I couldn't seem to find that, that's why I used the old fashioned way and double checked off the crank pulley mark.

 

[s3dave]

Guess work mate, get the codes logged instead of tearing your hair out, there will be somebody near you with vagcom... do a shout out...lol or if you can come to leeds/bradford i will do it for you.....

 

[DavidW]

Sandip kindly offered but I've only just got back and I'm out all day tomorrow cos it's my 30th! Looks like I'll have to take it somewhere and get it scanned on Monday, fingers crossed it's nothing too serious, I can't face pulling it all apart again!

 

[DavidW]

All sorted, had a miriad of codes at first but I guess that was from when the belt went, cleared those and it showed a misfire on no4. A trip to Blackburn Audi and 4 new free coilpacks later it's running better than ever. So chuffed it was nothing serious, I'd worked late nights all week putting it back together, I don't think I could've faced taking it back in bits!

 

[s3dave]

Well done mate, glad your sorted...

 

[badger5]

coils dont like being disturbed.. fragile inside when baked on top of the very hot rocker cover