Help, Cupra R Misfire when cold

[JackK]

Hi, Have been having some issues from cold for the first 1-2 minutes of driving experiencing a misfire on cylinder 2 with the car struggling and car gets stuck around 2-3k revs. This clears pretty quickly and then the car drives perfect doesn't break up under acceleration etc. I have moved coil packs but stays in cylinder 2, changed spark plugs, Maf, coolant temp sensor, cleaned the throttle body and have had a smoke test with no leaks and injectors swapped with no change and have now replaced the top section of the coil pack loom. All without solving the issue. Only code that comes up is a misfire and nothing else?
Any ideas would be welcome as its driving me mad and ruining any enjoyment of the car

Thanks

 

[mty12345]

Does it only happen when the SAI is running? (This only runs if the coolant temp is below 30C when first started) If so then it's something to do with that.... I think you'll find it's either the SAI combi valve or the SAI pump itself.

It's known that the rivets fail and cause an air leak at the pump. You can just drill them out and replace with some small nuts and bolts so that it's air tight. That would probably be my first plan of attack, followed by replacing the SAI valve. Hope that's some help.

 

[JackK]

I didn't think Cupra R have the SAI System? I could be wrong and would love to have another option to try and sort this.

 

[mty12345]

I didn't think Cupra R have the SAI System? I could be wrong and would love to have another option to try and sort this.

Sorry mate, my bad, didn't realise that they don't have it on the R. In that case i'm stumped too.

 

[mty12345]

Just been sat thinking about it and the only thing i can think of is perhaps you have a valve stem seal allowing oil to leak back into that cylinder over night? Either that or some sort of valve issue that isn't seating properly until the engine has warmed up a bit.

Edit: also have a look at this. I guess water could be the issue too. https://dubberz.com/forum/all-about...sfires-rough-cold-starts-coolant-in-cylinder/

You can get some very cheap usb endoscopes on ebay now. Maybe you could take the spark plug out and use one of those to look inside first thing in the morning to check for oil/water in there, so you don't have to strip the head.

 

[JackK]

Sounds like that could be maybe be it, Any idea on costs with getting this fixed? I imagine expensive?

 

[mty12345]

Depends what the issue is really mate. If it turns out to just be the stem seals, then if you can take the cylinder head off yourself, then i would imagine you're looking at £300-£500 to have it refurbished.

I still think an endoscope may be the best bet to confirm if this. This one will plug into an android phone. http://www.ebay.co.uk/itm/Waterproo...hash=item465dfb9da8:m:mXkWK1_NZgNptbqvGPoDfAg