HC double CO little over rough in 3rd

[genealogyman]

95 ranger 2WD 4.0 L 230k My HC was double allowable CO a little over and the engine runs rough on the low end of 3rd gear particularly uphill. Changed Air filter and checked vacuum with starter fluid. MAF appears fine. what else can I check? MUffler place doesn't think it is the CAT. what else?

 

[Andy D]

O2 sensor(s) ? Coolant temp sensor? Weak spark?

 

[Pauls 4x4]

Do a lot of smog fixes here in California. They sell cheap cats that don't go 2 years but that's all your allowed to buy...

Anyways I'd check your plugs (first culprits high HC) , but to get that crazy rich (assuming CO #s like CA) if I'm avoiding saying it's the cat (sounds like 99% a plugs and replace the cat because bad plugs killed it job)... And the self check doesn't pop anything it sounds like a leak between engine and the cat (the extra o2 makes the engine think "lean" and pour in gas. Which would also fry the cat.

Now, it can be mechanical on HC. Any tapping etc? My high HC was a dead cylinder.

But the maf, ect, ait, 02, or tps are your sensors that can cause a rich condition (like all of them).

Yet my question is what's the #s. In California it's like 120 to fail so 240 would be like liquid coming out the tailpipe.