Quote:
Originally Posted by Mitco39
yes they tie in there and under idle the manifold is under a vacuum that sucks in crankcase vapors. Now before the kit the crankcase would be filled with air from the intake between the maf and the throttle body. But now this air is just entering the system through those two fiilters and straight into the intake at idle.
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Just throwing ideas out. Partially for my understanding and partially to see if any trigger some light bulb in your mind that leads us to a solution. I could be completely off but stick with me. So NA it's pulling metered air in from the intake (post-MAF). I would guess the ECU is expecting a certain amount of air to be removed from what it's metering, where in reality (vented) the crankcase is pulling in as much unmetered air as it wants. There is no adjustment for that air not being removed and when you come off throttle it hiccups because it's getting more air than it expects leading to the lean condition. Which is what we see happening.
But let me throw an additional monkey wrench. The GTM kit ties that secondary in pre-MAF, so it has to be something different or in addition to what I stated above or there is something in the tuning that can correct for that.