[jondagger]

I installed NGK 2-Step plugs recently. Gapped them to 0.023" give or take. I am noticing a +20% drop off in ignition timing #4 after passing 5.5k rpms or so. What do you think is the cause?

Below are some 3rd Gear BM3 logs. Running e40 + Meth.

http://www.bootmod3.net/log?id=5d37bc6ec090c63a4d63fb0b

http://www.bootmod3.net/log?id=5d37bc01c090c63a4d63fb06

Should I buy new gapping equipment and double check? My last chisel tool is KO. Thanks

[XutvJet]

It's going to be really hard to get a solid analysis here because you're pushing WAY more power than stock. It could be a gap, a bad plug, knock, poor fuel quality, a failing coil pack(s), a change in ambient conditions, the mood of the DME that day/week, etc. This whole plug gap thing appears to cause more issues than not in late model turbo BMW motors. The fuel and ignition systems are being pushed far harder than they were designed for and even in stock form, they operate within a narrow window. When you add a ton of power, you'll very rarely get a perfectly running car and will be endlessly tracking down oddities like this. The systems operate fine in stock form or slightly modded, but push them a lot harder and they start operating outside of their parameters and things can start getting wonky. It's just the nature of significantly modifying a car. You might think you've solved the problem, such as adjusting the gap slightly smaller, only to have the same issue appear 6 weeks later.

[jondagger]

Originally Posted by XutvJet

It's going to be really hard to get a solid analysis here because you're pushing WAY more power than stock. It could be a gap, a bad plug, knock, poor fuel quality, a failing coil pack(s), a change in ambient conditions, the mood of the DME that day/week, etc. This whole plug gap thing appears to cause more issues than not in late model turbo BMW motors. The fuel and ignition systems are being pushed far harder than they were designed for and even in stock form, they operate within a narrow window. When you add a ton of power, you'll very rarely get a perfectly running car and will be endlessly tracking down oddities like this. The systems operate fine in stock form or slightly modded, but push them a lot harder and they start operating outside of their parameters and things can start getting wonky. It's just the nature of significantly modifying a car. You might think you've solved the problem, such as adjusting the gap slightly smaller, only to have the same issue appear 6 weeks later.

Good insight. Does make sense. The logs attached are in a more humid climate than usual. Last week I did multiple logs and didnt find this "issue", the tune was mildly less aggressive in high rpm boost + less humid. Then 2 weeks ago I had an even less aggressive tune overall and the issue was noticed.

Its on and off but seems to only happen on ignition #4. Maybe some upgraded coils and checking the gaps isnt a bad idea....

[jondagger]

I had a buddy tell me that those cylinders is where most my meth sprays... #3 and #4... could be related to that? upgraded coils isnt cheap either lol

[jondagger]

http://www.bootmod3.net/log?id=5d391b68c090c65e9f4f8eb3

+1 more.

The timing has seemed to go away the next day. Seems on - off. The gap for the #4 was 0.025", i adjusted to 0.022. This log includes the spark plug regap but the timing was fine before the gapping too, just wanted to be proactive.

[Jeff@TopGearSolutions]

Might just be that cylinder is running differently. Swap coils and plugs separately and see if the problem follows. As someone else mentioned methanol flow that isn't port injection isn't going ot be perfect either.