Misfire when up to temperature

[Jfox]

Hi guys,

The cupra has developed a horrible misfire when up to temperature.

When its cold no problems but as soon as the engine has got up the temperature any boost will cause it to misfire.

Scanning on brings up codes for random/multiple misfiire and misfire cylinder 1 and 3.

I changed the coil pack (1+3) before i came to the realisation it was only when warmed up.
I also have a new set of spark plugs that i'm going to put in over the weekend.

My question, what else could it be? I think, correct me if im wrong, that when the engine is at operating temperature the fuel is leaned off compared to first starting. Could the MAF sensor be cutting fuel for some odd reason??

Any help much appreciated at usual.

Thanks

 

[RnPnJ]

Make sure your issuing the NGK plugs. Check to see if the misfire follows if you swap plugs and coil pack.

 

[GordieC]

I had this on cylinder 3 a few years ago. I ended up having to replace the injector on the cylinder as well as carrying out de-coking of the inlet valves and plates/ports. I used the guide posted on this forum. They were caked in carbon buildup. It made a massive difference. Since doing it, I still see the odd misfire logged on Carista but this is usually if I've left the car idling for 5+ minutes and it's never enough to throw up a ECU light like it did before.

The coking issue is a common vault with all direct injection VAG petrol engines. You'll notice a big difference if you do it.

 

[Jfox]

Well so far so good with the car.

I had the two remaining coil packs changed and a set of sparks and at the moment its running good.

So i suspect a dodgy coil pack fried the spark??

Also not helping is the fact my carbon intake coupler has a massive rip in it. Probably causing a bit of over fueling too. that is soon to get fixed.

 

[anz]

my seat leon tfsi fr 2007
while I drive on low revs rpm drop to 800 from 1500 at 20 mph and shake some times violently same when 70 mph from 2500 to 2000.
this happens sometimes but every day when I drive.
I have changed spark plugs, coil pack,pcv valve, high pressure fuel pump, cam followed, breather pipe, maf cleaned.but still no luck.
please help me

 

[R3k1355]

Have you changed the diverter valve?

 

[anz]

it was the crank position sensor the mechanic solved the problem