So, I decided to take in my 1987 Montero 2.6 to get tested today so that I could get my plates. They do a safety and emissions test here, everything passed with flying colors EXCEPT I failed emissions due to high CO levels, thus, the car is running too rich. The max in Utah is 1.58 @ 15 MPH and 1.62 @ 25 MPH. I blew 3.71 @ 15 MPH and 3.72 @ 25 MPH. Both are almost double the maximum. The vehicle has a new Cat, replaced about 6 months ago so I don't think that is the problem. From searching posts, that seemed to be the problem for most. I am ruling that out for now.

The guy at the smog station said it could be a faulty O2 Sensor (which I think would be quite easy to replace), a mass air flow sensor (which I don't think I have), or a missing vacuum hose somewhere. Does anybody have an idea of what the problem could be?

I only get one free retest in a month so I really want to get it right. If anybody with experience with this issue could chime in, it would be much appreciated.

I've recently replaced the distributer, coil, plugs, PCV Valve and fuel filter.

Thanks Much.......Brian

hey...

I have the same problem. Mine is an '87 Montero w/ California emissions. This seems to happen to me every year (I live in Utah too) where the CO levels are twice what's permitted. Actually, the 25mph test passed but the low one didn't. I think it tested at 3.09. Every year its the same. Normally, I'd just talk a mechanic into having 5 minutes w/ it hooked to the computer and then adjust the carborater, but this year every mechanic I've talked to has been useless. So, last week I replaced the O2 sensor and added some 'guaranteed to pass' additive. Well, it didn't work. On my retest the 10mph tested at 3.31 and the high at 4.01. This week I'm taking it to a mechanic. I'll follow up with you if you want. And, if you can figure it out in the mean time, I'd like to know.

j.d.

Hey guys....hate to take people from one site to another but got o 4x4wire.com. They have a very comprehensive group of posters in the tech section. They cover pretty much every topic including what to look into for the carb.
Check it out.

Glen