Missfires Idle - 1 Cyl

[Isaland]

Good afternoon

Seat Cupra R MK2 2011, CDLA engine

So I have popular problem, missfires on idle in 1 cyl. At the moment it do not throw any errors, but want to fix it before remapping to st2+.
Changed stuff: Intake Volant, Sparks 1675 with gap 0,6mm, Autotech Insert Kit, Wagner Intercooler, k04 muffler delete, RS4 PRV, Downpipe. Remapping st1.
So what was done/checked/changed:

1) New sparks NGK 1675 with gap 0,6mm. Also install same with gap 0,8 mm. Nothing changes.
2) Installed new coils NGK 48042
3) New lpfp VDO A2C53438283Z
4) Install new genuine hpfp, nothing changed - returned to previous autotech
5) Intall new injectors Bosch 0 261 500 037
6) Check PCV, check adsorber valve
7) Try to find air leak with pressiure, all ok
8) Check vacuum pump and vacuum tubes
9) 6000km ago clean carbon deposit on valves

When I run AC and rpm go from 720-760 to 800 missfires almost gone. On 1500 rpm and higher it totaly go away. No critical retards on high rpm. Have one moment when i check these missfires on VCDS screen , I run engine to 1500rpm and then release pedal, missfires go to 2 cylynder. And after few cycles it returned to 1 cyl. Very rare engine having missfires in other cylinders 1-2 per cycle.

Already bough endoscope and will check under valve cover on weekends.

Please, advice what can I check else?

 

[Isaland]

Also was removed MAF connector, nothing changed

 

[Chris78]

Maybe it sounds stupid but in my opinion should be good to try and also change the fuel filter. And always put a good high octane benzin when you fill your car and good brand like aral ultimate or she'll v power.

Check your filter and change it if it's old.

 

[Isaland]

It was changed when I bring it to Ukraine on 85k km... it pass 25k km. Anyway will change it, thank you.

P.s. Using always top gas stations, because car remapped 98\100 only.

 

[Chris78]

It was changed when I bring it to Ukraine on 85k km... it pass 25k km. Anyway will change it, thank you.

P.s. Using always top gas stations, because car remapped 98\100 only.

Yep. Change it. Me too also I had issues with misfirings and also bad economy and two things fixed my issues. I put a new fuel filter and I made a wheel alignment. My car is stage 1 tuned with 320hp and 420nm torque. Also don't use cleaning chemical agents for injector cleaning. They work but also they **** up the fuel filters... Don't ask me how I know it. ?

 

[Isaland]

Yep. Change it. Me too also I had issues with misfirings and also bad economy and two things fixed my issues. I put a new fuel filter and I made a wheel alignment. My car is stage 1 tuned with 320hp and 420nm torque. Also don't use cleaning chemical agents for injector cleaning. They work but also they **** up the fuel filters... Don't ask me how I know it. ?

I use only VAG G17 fuel additive once, but it not helped

 

[Chris78]

I use only VAG G17 fuel additive once, but it not helped

Now that you installed new injectors you don't need anything. For me I still have the old ones and I never even carbon cleaned my valves.. so I used sonax injection cleaner at least 3 times. It helped with the cleaning but it destroyed the fuel filter.?

 

[Isaland]

Small update: istall PCV delete kit - missfires almost gone, sometimes in the cycle they get to 1-2. Consumption reduced from jumping 0.9-1.1 to stable 0.9 on idle. But still intesting why these missfires occurs.

 

[Isaland]

After 2 days - missfires and rough idle return back So problem was not in PCV.... any suggestion?

 

[Chris78]

After 2 days - missfires and rough idle return back So problem was not in PCV.... any suggestion?

Still misfires? Damn...?
Last option you have is to go to a mechanic and test your car. Ask him to do a compression test also. With clean valves and everything else new your car must work without problems.. I can't think of something else ?

 

[Isaland]

Still misfires? Damn...?
Last option you have is to go to a mechanic and test your car. Ask him to do a compression test also. With clean valves and everything else new your car must work without problems.. I can't think of something else ?

1) Valvles was cleaned 6k km ago
2) Compression was about 12 in all 4 cylynders. Even look with endoscope inside 1 cyl, and ther was dry and clear with no damage

 

[Chris78]

1) Valvles was cleaned 6k km ago
2) Compression was about 12 in all 4 cylynders. Even look with endoscope inside 1 cyl, and ther was dry and clear with no damage

You need to go to a mechanic that is experienced with tfsi.. it's your only option my friend.. just go and tell him your issues. I'm also very curious of what must be the problem that mades those misfires. Good luck and have a merry Christmas also ?