Magnaflow Cat question

So i just took the newly built engine for a smog and failed horribly on NOx again. With the old engine it became a routine, change plugs, wires, cap, rotor, o2 sensor....take test, fail with High NOx, buy a cat, pass smog.

This time, since I got tired of paying for retests, bought the cat first. Still failed with high NOx and this is on a newly rebuilt engine.

This happened once before with a honda about 3 years ago. I bought a discount cat only to find it was a 2 stage, not 3 stage cat, and again failed with high NOx. Bought a cat from NAPA and passed.

So I'm looking at this MagnaFlow Catalytic Converter 39221, and on the box it says, "MEETS CARB CALIFORNIA AIR RESOURCES BOARD EMISSIONS REQUIREMENTS AND CRITERIA OF FEB. 15 1989" Didn't CA pass new emissions regulations requirements recently (like the last 5 years)? And could I just have the wrong Cat?

California just changed requirements again this January. Most aftermarket companies are out of stock on CA "approved" crap.

Yeah, didn't order this online though. I bought it at Kragen.

A guy at NAPA once told me that auto parts stores were not allowed to sell converters that were not legal for their area. When I first did a search for specs it came up as a 49 State converter. However, Magnaflow has it listed on their 50 State, EPA and CARB approved, catalog as well.

I mean if numbers were close, I might not be so convinced I got the wrong item (well that and the 1989 date stamp), but max for 15 & 25 mph were in the mid 500's, my scores were closer to 1200 and 1180 respectively.

The HC and CO, however, were well below average, and much less than max.

The engine doesn't run particularly warm, checked torque on the intake/exhaust, and it was all up to spec. There were some loose bolts on the valve cover, but no significant oil leaks. It has new Champion plugs, new wires, new cap, new rotor, new distributor, new NGK (OEM) 02 sensor, new IAC valve, new TPS...I can't think of anything else.

What plugs are you running? Renix likes the RC9YC plugs.

Champion copper, gapped 0.035.

I've always run Champion Truck Plugs, 4412. But they've been discontinued unfortunately.

Bah, just verified the executive order D-193-85 that's stamped on the CAT, unless there was a change as of this January that hasn't been posted yet, looks like the cat isn't it.

You need to look up your vehicle year on the magnaflow website and see what cat is correct. What year do you have? Here is the link:
http://www.magnaflow.com/02catalytic_converters/02product/02california.asp

SanDiegoXJ said:

Champion copper, gapped 0.035.

I've always run Champion Truck Plugs, 4412. But they've been discontinued unfortunately.

Click to expand...

Try the 430s, I belive that's the number that the RC9YC corresponds to. Those are the only plugs my engine will pass with, they are a cooler heat range. I keep a set and swap them in every time smog comes around.

Thanx Grimm, I'll give that a shot.

Just out of curiosity, would air leaking under the valve cover have any impact on NOx? almost all of my valve cover bolts were only finger tight.

No. Nox is directly related to high combustion chamber temps

Was the head decked when it was rebuilt? High compression can cause Nox to be high too (I believe).

Also, is this a renix or HO? If Renix, check the EGR that will help cool chamber and drop Nox.

I just went through the new smog laws with my 1990. The old after market cat was not on the approved list now. I had to buy a new cat. I bought the Magnaflo and installed it myself. My jeep passed with flying colors.

Jeep is a '94 HO with auto tranny.

I don't think a compression check was done on it, (I could be wrong tho). The engine was rebuilt by Mike Finch (Willy51), and he's turned out a few. This is the first to have this NOx issue to the best of my knowledge...also, the Jeep has had a history of failing with similar scores, it's just that in the past, a cat always fixed it....now it's getting the same score with a new cat.

Not sure if I mentioned there is also a small vibration under torque. It's most noticeable under low torque load like maintaining 25-35mph, but is also noticeable at WOT, it's just not as bad as low speed.

Another piece of history, this jeep did suffer an engine fire before the rebuild. The wiring harness was replaced, but many connectors had to be crimped on, such as the tranny comp connector and the fuel injector connectors.

Also, upon getting the engine, the vibration wasn't there. As it manifested itself into a more noticeable vibration, I found that the majority of the engine mounting bolts had come a turn loose, and the driver side mount was only held in place by three threads of one bolt, the nut on the bottom was completely missing.

right now it seems like it's back to the old vacuum leak search

EDIT: should also mention every sensor with the exception of the MAP, CTS, and CPS have been changed.

have you tried talking to finch about it? he's pretty good at what he does he might have some insight into it for you.

Yep, I've been working with him too. He thinks O2 getting into the combustion chamber or a bad sensor, but I cannot find a leak to save my life. I just coated every vacuum line in the engine with starter fluid and no variation in idle.

may try swapping out a map sensor or just biting the bullet and replacing it.

OK, so since the problem isn't the cat, I started a new thread in OEM tech

http://www.naxja.org/forum/showthread.php?p=245585477#post245585477

any help is appreciated.