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Rich to lean to rich between shifts and idle?

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English_Rugby

10+ Year Contributor
69
2
Jan 29, 2010
Saint Joseph, Michigan
So I have a 1g which I have spent a while on replacing all the harnesses and going through everything that I ever experienced a problem with, and I recently got it back on the road. When the car is running and driving between shifts it goes really rich, and if I coast in neutral or let it cool down while parking, for about 25 seconds the AFR + revs will go up and down from normal 13s/14s to completely leaned out, the revs will also move with this. I am wondering whether the sole cause of this would be because the BOV is VTA.. I know it is a greddy and the fittings are somewhat the same as stock, but my cold air intake doesn't have the fitting necessary to recirculate the BOV. I am sick of people getting pissed or getting excited and thinking I am trying to race them at lights as it revs right up to 2.5/3 K and back down, like I am feathering the throttle. (No, I don't want to race your sunfire....) Any help on this would be great, I wonder how much of this I could 'tune' out, or if it is all the BOV? Or something else entirely.. Thanks in advance. Also, when I first turn the car on and it's cold this problem doesn't happen, it runs without the fluctuation.
 
if you have a BOV that vents to atmosphere, you will run richer than intended because the computer has already accounted for that air that is being released ... stock system used a full recirculation style so that the measured air goes back to the motor.
 
I know it is metered air that the BOV is letting out, this is why I am wondering whether or not this is what is causing the erratic revving + AFR changes between shifts and at idle every time besides at start up.
 
Your non-recirculated BOV is certainly causing your issues between shifts. The reason you don't see as may issues when the car is just started up, cold, is because it's still in open loop and the ECU is ignoring the O2 sensors feedback. As for your idle issue it can be a number of things, one being that BOV being vented, best to always start with the typical boost leak test then move on though Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge) :thumb:
 
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