Quick question about crack in mid pipe before o2

[mob]

Hey guys, jsut had a quick question, not really a problem because its fixed now. But, before I put my car in hibernation, I always heard some kind of exhaust leak from the passenger side, I always figured it was the header not tight enough. Well when i took everything apart I noticed a very large crack right before the o2 sensor. Because of the color of the valves when I took the heads off I have reason to believe I was running lean. Do you guys think this could have attributed to that? Or would this have just made the car run with an exhaust leak and thats about it. I got it welded up, so I just want to know if the car will run better now.

 

[Foxfan88]

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.

 

[mob]

Thanks for the info man, thats exactly the info I was looking for.