Hello all.
First, thank you for the awesome forum, been lurking for some time before buying my first Jeep 2 months ago.
I was finally been able to get an emissions test done on my 1999 Sport. It failed miserably.
HC and Nox are well within range, but CO was double the allowable amount through the whole test. Jeep was up to temp and had fresh tune-up.
By the excessive exhaust noise in the engine bay, I think I have the common 4.0 cracked manifold, though I can't see any obvious carbon tracking. My scan tool shows short and long term fuel trims at about + 4% each, but I'm new to jeeps and am not sure if this is normal for the elevation I live at, about 5500'. Spark plugs have about 500 miles and are still nice and white. It does have an off idle stumble though, not sure if its a rich condition or the aftermarket throttle body spacer.
My only other thought is it could be the catalytic converter, but I'm thinking I should maybe start with the manifold and O2 sensor?
Any other ideas?
First, thank you for the awesome forum, been lurking for some time before buying my first Jeep 2 months ago.
I was finally been able to get an emissions test done on my 1999 Sport. It failed miserably.
HC and Nox are well within range, but CO was double the allowable amount through the whole test. Jeep was up to temp and had fresh tune-up.
By the excessive exhaust noise in the engine bay, I think I have the common 4.0 cracked manifold, though I can't see any obvious carbon tracking. My scan tool shows short and long term fuel trims at about + 4% each, but I'm new to jeeps and am not sure if this is normal for the elevation I live at, about 5500'. Spark plugs have about 500 miles and are still nice and white. It does have an off idle stumble though, not sure if its a rich condition or the aftermarket throttle body spacer.
My only other thought is it could be the catalytic converter, but I'm thinking I should maybe start with the manifold and O2 sensor?
Any other ideas?