mechanically, an exhaust leak has no effect on the fueling/performance of the engine. it'll just be annoying.
EFI wise, an exhaust leak pre-o2 sensor can affect the fueling of the engine.
In CL the EEC trims fuel via the o2s, in a nutshell the EEC will add/subtract fuel to get the o2 to "switch" It will add fuel until it switchs, then start pulling it till it switches again, and will keep repeating this thousands of times while the engine runs as long as the EEC is in closed loop.
And exhaust leak at lower rpms can pull ambient air from the outside, this extra o2 mixed in with the normal exhaust, it will show as leaner to the o2, the EEC will inject more fuel to react to what it thinks in "lean". So with the extra fuel PW added along with the exhaust leak, the o2 switching will actually be a little richer within the engine, or at least on that side where the exhaust leak is.
At WOT the EEC runs in OL and plus there is more PRESSURE in the exhaust, so i doubt the crack will allow free air in, rather the exhaust will come out under those conditions.
EFI wise, an exhaust leak pre-o2 sensor can affect the fueling of the engine.
In CL the EEC trims fuel via the o2s, in a nutshell the EEC will add/subtract fuel to get the o2 to "switch" It will add fuel until it switchs, then start pulling it till it switches again, and will keep repeating this thousands of times while the engine runs as long as the EEC is in closed loop.
And exhaust leak at lower rpms can pull ambient air from the outside, this extra o2 mixed in with the normal exhaust, it will show as leaner to the o2, the EEC will inject more fuel to react to what it thinks in "lean". So with the extra fuel PW added along with the exhaust leak, the o2 switching will actually be a little richer within the engine, or at least on that side where the exhaust leak is.
At WOT the EEC runs in OL and plus there is more PRESSURE in the exhaust, so i doubt the crack will allow free air in, rather the exhaust will come out under those conditions.