Recently failed MA emissions and need help figuring out why. I recently replaced my O2 sensors so I know its not that. I even had installed a NRP catback s.s. exhaust. I'm hoping that the problem isn't with the catalytic converters. Anyone have any information?

The exhaust really stinks (like rotten eggs (literally)).
thanks

Oh and the test results:
CO2 at 2390 RPM was 13.6
at idle they were 13.2

CO was 3.05 at 2428 RPM
at idle they were 2.93

HC was a range of 140 to 149

the test failed at CO because the cut point was a 2 and I scored a 3.05 so i'm not sure what the cut point for CO2 was.

 

If your exhaust smells that bad then you are running way to rick and your cats are having a hard time handling it.
How many miles on your truck, what has been done tune wise and what octane gas are you using?
Mike

 

I had been running the highest octane available since i've bought the truck and I haven't done anything tune wise. What do you suggest and how do I go about doing it? I've looked at many other threads and they all seem to point to running rich but with no explanation on how to solve the problem. thanks for your help!

1992 R.R.C.
2002 SE7

 

So what year, model and mileage vehicle are you talking about.
Mike

 

1992 Range Rover Classic with 145,000 miles.

 

That probably tele part of the story. If you are running on old p;ug wires and tired plugs, this would be the first place to start along with a new cap and rotor.
I would consider an engine flush a big plus as well as an induction cleaning and a tank full of good gas additive.
If you want more details, send me your tele number and a good time to call and i would be glad to walk you thru this.
Also pul one spark plug from each cylinder head and not their condition before we talk.
Mike
mikeljcaobs@comcast.net

 

Thanks for the great info Mike. You mentioned "I would consider an engine flush a big plus as well as an induction cleaning," How would I go about doing that? Is the induction cleaning taking off the plenum chamber cap and using brakeclean or something to clean out the deposits?

 

With your mileage, a engine flush would cut alot of sludge from the engine and crank case, raise the compression a little, improve the oil flow and get rid of a lot of hydacarbons.
I would do the 6 qt.s of ATF flush and clean it out good.
As for the induction cleaning, doing this will remove alot of carbon from the intake valves, also clean the throttle body to improve engine response.
If you decide you want to do some of this get in touch with me and I'll walk you thru it.
Mike

 

Do i just dump the 6 quarts in after draining the oil, let it sit in there for awhile, then drain and refill with oil?

 

Drain your engine, reuse the old filter, add the ATf and let the engine idle for at least 20 minutes, NO DRIVING. Then drain it and do your regular oil change.
Mike