leaking air box

[quartetchiang]

Guys:

Pardon me for a very novice question. Can a compromised (deformed due to heat) thus leaking air filter box on a 3.2 Carrera cause serious mixture deviation? If so, more likely to be too rich or too lean?

(I know, very basic..)

[darrin]

on a 3.2 motronic, the air filter box is upstream of where the AFM meters airflow -- so it air leaking around the air filter on a 3.2 shouldn't cause any mixture issues (on my 911 the airbox has been replaced with a cone filter w/o issue).

on a CIS engine, otoh, the airbox is sealed and a leak, etc. will affect mixture.

if you're suffering from mixture issues, I'd look downstream of the AFM for issues

[quartetchiang]

Let me be more specific. I just changed spark plugs. Cylinder 1 seems to have firing issue, plug is all black and oily. Changed ignition wire 1-3 hoping to fix firing issue. Started car, at first extremely smooth and normal. After about 2 minutes, idle starts to unstabalize. exhaust starts to smell irritating. Feels like mixture confusion.

[quartetchiang]

Thanks Darrin, that makes sense!

[darrin]

no problem -- If limited to cylinder 1, I'd start by checking the intake manifold to confirm it's tightly attached and leak-free. Also, what's your oil consumption like? black/oily could indicate bad valve guide?

[timmy2]

Slipped intake gasket? According to John Walker fairly common.

[quartetchiang]

Thanks Timmy2! I will also look into that.