Tuning question for those with expirence. - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Trob85 · 05-02-2020, 01:53 PM

Just had my car tuned and ran into some problems the guy said it was getting spiked of knock and running lean also at 6000 rpm the boost would flatten out at 10 psi. No belt slip, no boost leak, good plugs and wires and really good compression. We did a street pull to log data and hit 12.6 lbs of boost and air fuel was 10 with E85. Looked at the log and the spark table read 17 in the 5600 range and at 6000 rpm 20 all the way down and 15 in the next graph. Is that something that could cause knock or even be a reason I’m losing boost at that rpm?

co14camaro · 05-07-2020, 09:00 AM

At what RPM did you hit 12.6? If the belt is not slipping then something else is going on. Has the VVT been adjusted to dial out some valve overlap at higher rpms? Too much overlap will allow pressure out of the chamber before ignition and will show as a loss of boost pressure. Basically boost goes straight into the exhaust without being combusted. I should say my comment only applies to LLT and LFX motors. On the V8 you need to make sure the cam profile is made for forced induction otherwise the same thing can happen.

xc_SS/RS · 05-07-2020, 10:35 AM

Take some screenshots or post the log here so we can get a better idea of what’s exactly happening

05-02-2020, 01:53 PM	#1
Trob85 Svt lol Drives: 2011 ss inferno orange blown Join Date: Jan 2012 Location: Topeka Posts: 2,312	Tuning question for those with expirence. Just had my car tuned and ran into some problems the guy said it was getting spiked of knock and running lean also at 6000 rpm the boost would flatten out at 10 psi. No belt slip, no boost leak, good plugs and wires and really good compression. We did a street pull to log data and hit 12.6 lbs of boost and air fuel was 10 with E85. Looked at the log and the spark table read 17 in the 5600 range and at 6000 rpm 20 all the way down and 15 in the next graph. Is that something that could cause knock or even be a reason I’m losing boost at that rpm? __________________ plasti dip is not a mod.......and a cold air intake doesn't make you fast!

05-07-2020, 10:35 AM	#3
xc_SS/RS Drives: 2010 Camaro SS/RS Join Date: Mar 2014 Location: somewhere in MD Posts: 4,883	Take some screenshots or post the log here so we can get a better idea of what’s exactly happening __________________ 2010 2SS/RS Z/28 intake, NW, FAST 102, speed engineering LT's, some exhaust, ATI -10% pulley, GM flex fuel injectors, DSX flex fuel sensor, MGW shifter, HP Tuners, some suspension work, stickers and a little weight loss. 12.63 @113.53

05-07-2020, 09:00 AM	#2
co14camaro Drives: 2014 Camaro Join Date: Feb 2020 Location: Aurora, CO Posts: 66	At what RPM did you hit 12.6? If the belt is not slipping then something else is going on. Has the VVT been adjusted to dial out some valve overlap at higher rpms? Too much overlap will allow pressure out of the chamber before ignition and will show as a loss of boost pressure. Basically boost goes straight into the exhaust without being combusted. I should say my comment only applies to LLT and LFX motors. On the V8 you need to make sure the cam profile is made for forced induction otherwise the same thing can happen.