left the old sensors, so the O2 sensor code was still there. I drove about 500 miles, then replaced the O2 sensor with a Bosch & reset the
computer. The CEL came back on, with the cat low efficiency code again. The new cat's OEM, and I have low to medium confidence in the guy
who installed it (long story).
To complicate things, the car has exhaust headers and an after-market air intake with a sketchy foam vent (which I'm planning to replace
but haven't yet - could that affect my emissions?) It also has california emissions - I'm unclear on whether that affects the ODBII, or if
it's just a certification. The few mechanics I've talked to want to put a manifold back in, which seems dumb to me, as I get 4-8 mpg
better than CAFE ratings. You'd think I'd be able to get the computer to like the aftermarket parts. That said, I still need to fix this
so I can pass emissions, so ultimately I'll go to stock if I need to.
I'm wondering whether I could have poisoned my new cat by using the old bad sensor (& therefore running too lean) for so long. Someone
also told me that the cats could have been poisoned by the extra heat from having the headers instead of a manifold - that the exhaust
doesn't cool enough since it gets out to the cat faster. That story seems unlikely, since the difference really isn't that big.
I've also read that this could be a mass airflow sensor problem, but I don't understand how that works.
So the options I've thought of are:
- replace just the cat
- replace the cat & both sensors
- go back to a stock manifold & replace the cat & both sensors
- replace the mass airflow sensor
- fix the intake
I want to spend as little money on this as I can, but I want to make the fix permanent. That also means I'd rather buy OEM parts (vs.
paying the dealer markup), but I can't swap the cat out myself, as it's welded in.
What do you think the most likely problem is, and what's the best bet for fixing it? Is there anything I haven't thought of here?
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Friday, February 8th, 2008 AT 5:49 PM
