Quote:
Originally Posted by Chooch84
The stock ECU can only take into account the air that has gone past the AMM, any that has been vented to atmosphere isn't metered by the ECU in any way so it can't really make a decision based on something it doesn't know. The AMM has told the ECU that more air has gone past it hence the leaning out. MAP sensors are generally used by themselves or in combination with a MAF to overcome this issue (modern OEM ECU's), but then you'll be looking at going Standalone.
The CBV of the stock turbo vented this back into the turbine housing to help it stop stalling and as well as controlling the amount of air going passed the AMM. No extra air should be going passed the AMM when the CBV recirculates, therefore the ECU knows the amount of air in the system and can work out the fueling according to that.
Ideally, your BOV should be placed after the intercooler as that when the air is most dense.
As it's been mentioned before, ideally, the vented air needs to be recirculated to work with the stock ECU. However, there are members of this forum that have figured out how to 'overcome' this issue on the stock ECU, I'm not one of them!
Hope this clears things up...
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I know alot of people think this, but IMO its mostly wrong.
The unwanted air gets dumped out the air filter (this is physics), the MAF is mostly (but not completely) gnored during idle. The problem is the TB and idle valve cannot control the high pressure air for idle, it has to be dumped. Air flow is 'assumed' during idle and the O2 +Rpm used for feedback.
The CBV just stays open during idle, so its good to connect after the MAF.