will exhaust manifold leak cause lean idle and rich under boost - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

spools420a · 12-09-2022, 03:00 PM

i have a lean idle/rich under boost,idle is 17afr and under full boost im seeing 10.0 afr.
boost leak tested the induction system at turbo inlet and only had minor leaks at 15 psi which i fixed,i then pressurised the exhaust and found a leak between the turbo and manifold which is now my suspect.

i understand how this will creat lean under idle as venturi effect from pulses draw air in but i dont understand how this could create a rich mix under wot because the manifold becomes pressurised how would this create a rich mix?

any thoughts?

12-09-2022, 03:00 PM	#1
spools420a Zilvia Junkie Join Date: Dec 2009 Location: phoenix az Age: 42 Posts: 460 Trader Rating: (1) Feedback Score: 1 reviews	will exhaust manifold leak cause lean idle and rich under boost i have a lean idle/rich under boost,idle is 17afr and under full boost im seeing 10.0 afr. boost leak tested the induction system at turbo inlet and only had minor leaks at 15 psi which i fixed,i then pressurised the exhaust and found a leak between the turbo and manifold which is now my suspect. i understand how this will creat lean under idle as venturi effect from pulses draw air in but i dont understand how this could create a rich mix under wot because the manifold becomes pressurised how would this create a rich mix? any thoughts?