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COBB OTS Stage 1 93OCT


Mods are:

K&N panel filter everything else is stock


Been logging since I bought the car never a out of range value until last weekend, I noticed the AFR was swinging to -20.34 when I let off the gas. I thought that was odd so I started logging and noticed that btwn 3500-4700 RPM I have a FKL varying from -.8 to -3.5 and knock sum of up to 34. Car is not daily or weekly driven and at the time of noticing this I had 1/4 of 93 OCT.


I noticed that the knock sum will tick up 1 or 2 when I take off from a light but wont go up much while driving. I have been reading the blogs on COBB and the reviewing their videos to get familiar with the combo of causes that can result in these type of logs so bear with me:)


Anyway Id like to get some advice as to what to check on the car to resolve the issue. Given that odd AFR swing I may replace the AFR as I am unsure of the age since I bought the car used back in June.


End goal is to identify and fix the mechanical cause(s) then hand it over to Mach V here in VA for a Dyno Tune :)


Thanks in advance




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Found the cause of both my concerns:


1. Missing DP to transmission bolt (After I replaced the turbo I reinstalled the stock DP didnt realize there was a DP to Tran connection near the bellhousing) that was causing the knock sum (that connect is near the knock sensor) to tick up while taking off.

2. Bad AFR sensor and likely failing/original 160K O2 sniffer replaced with new Desno AFR and O2 sensor

3. Flashed to 91OCT map but I still run 93 OCT fuel. The tuner can determine if I should go 91 or 93

4. Replaced plugs with NGK gapped to .031 OEM plugs(this was more for baseline purposes I never had a misfire(s)


Rest ECU went for a 30 mile drive on the highway DAM learned back up to 1 no FLKC, FKC, KS or wild AFR i.e. -20.34

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