13 z smell after high revs

Dreadnaught

Exhaust Gas Recirculation (EGR) would be around idle. On some cars the intake valves are open just enough on the exhaust stroke to let some exhaust gas back into the intake runner. The exhaust gases cool then find their way back into the combustion chamber on the intake stroke. Exhaust gas helps lower combustion temperatures which reduces NOx.

To use a diesel for example if the EGR valve is stuck open while trying to accelerate there will be a lack of power and black smoke out of the exhaust. This is because the boost is going through the EGR valve, through the EGR cooler and out through the exhaust manifold.

Where ever you read that exhaust gases increase performance makes me laugh.

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Ford Diesel and Heavy Line Technician at your service.