After dealing with a P0503 code, I came across a pending code on my Scabguage2; a P0303. I disconnected the 3rd coil and there was no change in idle, so I thought to myself "I just replaced these coils last year they cant already be bad!" I then took out the coil from the bad cylinder and replaced it with all the other coils and saw that there was no change in idle with any of the swapped coils it was only happening on cylinder 3. Wicked weird. I took out all my spark plugs and checked the gap and they were all at .6mm as per requested by NGK. I continued to try to find the source of the problem and thought to myself that I should just check the compression and found that cylinder one was 10.1, cylinder two was 10.3, cylinder three was 10, and cylinder 4 was 9.9. So it ruled out any possibility that I had a bent valve or a broken valve. I proceeded to disconnect the cylinder three coil and take out the coil while the car was running; I then reconnected the coil while the car was running and put the coil back into the cylinder, I noticed when the coil was barely seated on the spark plug I could hear arcing and the car ran very smooth as it should normally, as I went to push the coil back onto the spark plug the motor started to misfire yet again. WICKED WEIRD I know. I will check continuity tonight on the connector to cylinder three and hopefully find that it is something having to do with the wiring harness. If anyone has any input it would be greatly appreciated.

PS 2007 R56s N14 RPM stage 2
PSS I might be able to add the video I took last night I will post it if I can if not please DM me on Instagram @r56_tyler and ill send it over to you

Thanks again!!

 

At first, I was gonna tell you that Cylinder 3 most likely had no compression and I was gonna show you a photo of my exhaust valve having a hole in it but since you mentioned that all 4 cylinders have good compressions......that would be so weird. Let me know on exactly what you find.

 

Sure not a problem it sure is an oddity, I was not able to check continuity last night because is was down pouring here all day yesterday but I will try tonight!

 

*UPDATE*

So last night after work I went to check the continuity of cylinder three and found that black(negative) to green(power) was ~14v and black to blue(signal) was around ~10v while the car was running. I compared the voltage to cylinder four and found the same voltage as cylinder three; so that rules out the wiring harness could be at fault causing the misfire. Is there something that I am missing here? Is there anything else I can do? I dont believe that it could be the injector because when the coil is barely seated on cylinder three the car smooths out. I was able to pull fuel rail pressure and found that it was around 700psi. Please let me know next steps I really want to drive my car this summer lol.

Tyler
Instagram: @r56_tyler

 

Did you try give the wiring harness a massage while the car is running? Anything funny maybe with the ground connection at the valve cover?

 

*FINAL UPDATE*

For those who have read this and have reached out I would like thank you. I cleared all codes before I went out for a drive and still noticed that I was having the same misfire on cylinder #3. I drove to a buddy of mines house to see if the code was going to disappear after a short drive. I stopped in front of his house to show him what was going on and he asked “what does it do when the coil is fully seated now that you drove it” I then showed him and to my disbelief the coil fully seated on the plug the car had a normal idle and no codes. I guess I just had to drive it for a few minutes to clear what was going on! Thanks everyone I’ll keep you posted on what’s next on the to do list!