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Discussion Starter #1 (Edited)
So under hard acceleration I noticed today I hear a popping sound. Like 2 or 3 pops almost like a misfire. It doesnt sound like detonation. My plugs are gapped at .022 and my air fuel is right around 11.2 with 10 degrees ign advance on e85 d16y8 21psi boost from a garrett 57 trim, log manifold, stock head. What do you guys think?
 

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I was thinking the AFR sounded rich and it could be lighting off excess fuel post combustion chamber. You can definitely try and lean it out some. What wideband are you using?
 

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Discussion Starter #5
I was thinking the AFR sounded rich and it could be lighting off excess fuel post combustion chamber. You can definitely try and lean it out some. What wideband are you using?
Im using an Innovate LC1 wideband
 

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Discussion Starter #8
Ok I am going to upload the tune from the tuner before I messed with it, check plug gap and do more datalogs. I pulled the plugs yesterday and cylinder 3 looked like it had a bunch of soot on the plug. Ill clean it up and see whats going on.
 

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What plugs are you running? I'm sure they are the right temperature, but you never know.

I'd click your sig and check out your build, but I can't yet... haha
 

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Make sure you're calibrating it regularly. I like to wipe off the tip of the sensor with a lint free cloth with some rubbing alcohol as well, just man sure nothing gets into the sensor body
LOL this sounds too much like a personal hygene recommendation, if you didn't know he was talking about an O2 sensor..

OP I have the same wideband, I would think 11 AFR is too rich, leaves extra fuel that could ignite as it enters the manifold. What plugs do you have/gapped.. I think the best would be NGK BKR7E

If ANYTHING maybe running 10 degree is firing the spark too late, therefore not ALL the fuel is being burnt and then it pops as it enters the hot exhaust manifold -- see below.. SO you could keep it at 11, but advance the timing a bit and see if it helps.. my .02.

Wikipedia Quote:

"Backfiring in internal combustion engines occurs outside of the combustion chamber, and is typically the result of an improper air to fuel ratio. An overly lean air-fuel mixture (i.e. an overabundance of air) can lead to a failure to ignite in the combustion chamber, also called a "misfire". The unburnt fuel then enters the exhaust system, where hot components can cause the fuel to ignite unpredictably. Alternatively, rich air-fuel mixtures (i.e. an overabundance of fuel) can result in incomplete combustion, again causing unburnt fuel to enter the exhaust system."
 

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I leaned it out to around 11.7 and it stopped missing so I guess it was too rich
Sweet! You may notice some more power by leaning it out. Hard to tell without a dyno though. There are some dyno programs that work with logging software. They may be able to show you some improvements with a more lean ratio. The richness should just be there to eliminate detonation.
 

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Discussion Starter #15
I was doing some pulls last night and the popping came back. Seems to only do it around 7k. The datalog shows it leaning out when its doing it to around 13. If the spark was blowing out would that show up as leaner or richer afr's? I turned the boost down 2 psi and it seemed to stop.

Another issue I have is my EBC is overshooting my target boost. If I type 18 for target boost say in 3rd gear, I get around 20 at 6k rpm.
 

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what engine management are you using? post up your map and a 3rd gear datalog ill try to help you out
 
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