R&R on exhaust manifold upcoming

[NachtRitter84]

2005 SXT ATX 2.0L stock. Going to do an R&R on exhaust manifold soon, pretty sure it just the gasket leaking but if I’m going through the effort anyway....

First off: how long can I get away with driving this on the daily with the exhaust leak? It’s minor right now but I know it’ll get worse with more use: thing is I’m traveling for the holidays, as in already across the country from home, and I don’t want to do this on the road as it were.

Second: since I’m already getting in there to do the manifold/gasket any minor mods I can do while I’m at it?

[occasional demons]

If it is leaking between the head and manifold flange, or the manifold is cracked, it can cause issues with ambient air sucking into the exhaust. This adds oxygen to the mix, so the o2 sensor reads it as lean, and the PCM will add fuel, to try to correct a problem that doesn't actually exist. It can cause some pretty erratic behavior, as it over corrects, then under corrects trying to hit the target air fuel ratio.

If it is leaking at the manifold exit to the catalytic converter, or the converter flex joint, then you could run it until it fell off. You might get something like a P0420 code/CEL from the downstream o2 sensor. But it won't impact the engine operation.

Not much you can do for mods there, other than a shorty header, which won't net you much of a gain over the stock manifold. If you got creative with the converter inlet, then a shorty header may make a slight difference.

But you will lose the factory heat shielding, and should heat wrap the wire harness in the area.

[NachtRitter84]

Pretty sure you just gave me the answer on exactly where the leak is without my asking lol. It is over correcting and burning fuel then dropping to sluggish performance with ridiculously good fuel economy then stabilizing to normal for days on end. Shorty header sounds like a mod project for another time. Supposed to be getting a wrecked SRT4 on my way home for a project car so I’ll keep it in mind for that I suppose?