Well, my new '90 RS just failed inspection. Everything was well within spec, except for the crazy NOx reading. I don't have the papers in front of me, but passing was in the 1100 range, and I scored a 2300 <img border="0" title="" alt="[Eek!]" src="images/icons/shocked.gif" /> . My first thought is to replace the cataltic converter, but what coulds have plugged it up this bad? I'm going to get a new cat, and exhaust this week, probably going with 2 1/4 or 2 1/2 plumbing depending on fit. Any recommendations on mufflers, or resonators. Would love to get the most power out of the engine, but not at the expense of lots of noise.
On a side, my Raider also failed miserably. During the dyno test, it was smoking so bad they actually stopped the test and failed it for visible smoke emissions. Doubt my sister will want to sink $$ into having it fixed. How hard would it be for an average joe who knows a socket from a crowbar to do?

Thanks in advance for all the help, ted.

Whoa Nelly! Don't spend a wad on the cat and exhaust yet. Chances are that high rating is from carbon in your EGR valve, pipe and plenum. The EGR valve could also not be operating properly. Get it checked first and cleaned or replaced depending on results.

I would do this first before replacing the cat.

Powell

NOx emissions are formed when there are very high combustion temps, like from a lean mixture. Three way cats and egr are what control NOx, but make sure the fuel system is ok - what was your CO and CO+CO2 and HC?

Nothing like jumping the gun. After doing a little searching here, I thought that the EGR could only cause slight changes in the NOx levels. Either way, here are the reading for the other measures:
STANDARD READING
HC 174 103
CO 1.56% 0.76%
CO2 14.3%
O2 0.5%

Thanks again for all the help and tips. Brakes are getting worked on this week, KYB's by this weekend.

Ted.

Mine failed w/ high emissions, but I also had "extremely high temp" in the comb. chamber, so we replaced cat, and water pump, then we passed <img border="0" title="" alt="[Smile]" src="images/icons/smile.gif" />

I just noticed that this was your '90 Monty that failed. I have a '90 engine disassembled to the short block and I don't think it has an EGR valve.

Post when you have results and a passing score...

Powell

The EGR valve is not on all Monty's, I know its on CA models, cause I have one.
If you do have one, its bolted to the intake plenum on the driverside, with a tube
running to it from the exhaust manifold. Typically the valve does not fail. What
usually happens is the plenum gets plugged, and is a real PITA to clean out cause
the EGR passage has a 180 deg bend. I had to remove my plenum, and have it
tanked and pressure washed. Real PITA.

Might want to read my post on this:http://www.4x4wire.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=69;t=007577

Good Luck

Thought that it would be a link, let me try again

http://www.4x4wire.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=69;t=007577