Hey guys, I was having issues with poor performance on Map 2 with 93 octane so I switched back to Map 1 and ran 93 octane from Shell for a full tank. On the next fill, I put in Lucas Oil Octane Booster which is supposedly good for 3-4 octane, giving me roughly 96-97 octane. I put the booster in on an almost empty tank, then put a full tank of 93 behind it.
Below is a snapshot of one of my logs after going through nearly half a tank to give time for the booster to mix in. My timing on cylinders 3 and 4 is "almost" always lower than the other four cylinders. Sometimes by as much as 6 or 7 degrees. The variance is most visible in third gear in the snapshot below, but I've seen the same issue periodically in 1st and 2nd gear.
For my mods, ambient temp, and altitude, about 230ft above sea level, my Stinger seems to be considerably slower than other Stingers with similar mods at higher altitudes and temperatures. I'm a solid .4 to .5 seconds slower than most other cars with similar mods (4.9 seconds DOWN a straight on-ramp on a cool, dry, 65 degree day). Any idea on what could cause this, now that I've ruled out octane?
Current setup: GT2 AWD, 19" OEM wheels with OEM Michelin Pilot Sport tires with more than half the tread life left, Denso plugs gapped at .022, DIY AEM intakes, JB4 with fuel wires, Map 1, 93 octane with a full bottle of Lucas Oil Octane Booster.
The only thing I can think of is that it has to do with the spark plugs. I gapped them all with feeler gauges and a BMS style screw gapper. Is it possible for a variance in spark plug gap or quality to cause this type of issue?
Any thoughts on what to look into would be appreciated. I'm tempted just to replace plugs 3 and 4 and see what happens, but if the issue ends up being something like the .022 gap being too small, I'd rather not waste the time/money to get nowhere.
Thanks in advance for any help!


Below is a snapshot of one of my logs after going through nearly half a tank to give time for the booster to mix in. My timing on cylinders 3 and 4 is "almost" always lower than the other four cylinders. Sometimes by as much as 6 or 7 degrees. The variance is most visible in third gear in the snapshot below, but I've seen the same issue periodically in 1st and 2nd gear.
For my mods, ambient temp, and altitude, about 230ft above sea level, my Stinger seems to be considerably slower than other Stingers with similar mods at higher altitudes and temperatures. I'm a solid .4 to .5 seconds slower than most other cars with similar mods (4.9 seconds DOWN a straight on-ramp on a cool, dry, 65 degree day). Any idea on what could cause this, now that I've ruled out octane?
Current setup: GT2 AWD, 19" OEM wheels with OEM Michelin Pilot Sport tires with more than half the tread life left, Denso plugs gapped at .022, DIY AEM intakes, JB4 with fuel wires, Map 1, 93 octane with a full bottle of Lucas Oil Octane Booster.
The only thing I can think of is that it has to do with the spark plugs. I gapped them all with feeler gauges and a BMS style screw gapper. Is it possible for a variance in spark plug gap or quality to cause this type of issue?
Any thoughts on what to look into would be appreciated. I'm tempted just to replace plugs 3 and 4 and see what happens, but if the issue ends up being something like the .022 gap being too small, I'd rather not waste the time/money to get nowhere.
Thanks in advance for any help!


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