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Old 05-31-2016, 04:42 PM   #1
evonschu's Avatar
Drives: Camaro ZL1
Join Date: Oct 2012
Location: Hillsboro, OR.
Posts: 139
Question 10" Pulley Tuning Help

Hey all. Been working with a great shop in town and got some mods on my 2013 ZL1. Put on kooks no cat headers, 10" LPE pulley, id850 injectors, and tuned. Already have RotoFab CAI, and CMAX ported TB, and extra reservoir for coolant.

Been having some issues where when I go to accelerate sometimes the car chugs a few times before launching. It's been a process getting the tune hammered out, specifically in this transient area of acceleration. I believe what the tuner at the shop was saying was that the pulley is pushing out so much air in that less than 50RPM range when I punch it, its pulling timing or something along those lines. Gone with him on several rides with his computer and HPTuners. Tried adjusting lots of different values, mainly centered around this small area when I accelerate hard from a cruising speed. Some things have helped but still continue to have this issue.

Got new plugs in and that helped a ton with IAT2 temps, but didn't solve. If I'm already at higher RPM and then punch it I've never had the issue. But If I'm cruising at about 1-2k in any gear and step on it, it'll usually happen. It also seems worse if I downshift and rev match, then floor it a second later in the lower gear. Or similar situation, I rev the engine and then punch it while cruising. The weird thing is it doesn't happen every time. Sometimes I punch it and it feels ok. I'd say about 1 out of every 4 times it'll chug like this prior.

For those of you guys running 10" pulleys with stock size SC pulley any advice on what might be causing this? The shop I've been working with is very good and we've both been confused as to why this continues to crop up.

Thanks for any info. I've attached the dyno results too if that helps. It will never happen while on dyno though, just street driving.
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