Mitsupartsman.com: You may be right about the cat. I didn't think that replacing the O2 sensors was a bad idea though since I've always replaced the O2 sensors when putting in a new cat so doing it in 2 steps just costs me a bit of time to r&r the sensors.

I guess I'll see this weekend if the faults reset on my long trip. My friend with the OBD reset tool has not come through with it.

I have not done anything to the intake manifold lately. Several months ago I replaced the right side exhaust manifold after it cracked badly. That's about the extent of work on the engine in the past year.

I did find something that looks like a vacuum leak however. There is a small brass tube sticking up at the right rear of the throttle body that is sucking air so obviously exposed to the vacuum. I looked but did not find any hoses that were disconnected. I'm planning to plug that tube before the trip this weekend since I'm almost certain it should not be open. I have not been able to find any photos or diagrams that show this part or the hoses in that area on any of the photos/diagrams of the engine that I have. Any help would be appreciated!

Thanks for all the help Ron and everyone else that's responded. I'll let you all know what happens after the weekend.

One other unrelated thing... I don't have an owner's manual so I don't know what it is but there is a button on the dash just to the right of the instrument cluster labeled something like "A/T Mode". No lights just 2 positions - In or out. I've pressed it but have not seen/felt anything different about the way the car feels or runs. Can someome tell me what this button does?

Don

 

I don't have that engine but is it near the EGR Valve? Smog tech has to disconnect the EGR line to check the valve operation. But if this was the problem the line should be nearby. Maybe you could post a photo?

Ron

 

Well, I promised you an update when it was available so here it is...

I replaced all 4 of the oxygen sensors and my wife drove the car about 200 miles before I checked it again. I bought an OBD scanner and reset the fault codes after putting in the new sensors and after the 200 miles of driving it indicated that everything was working correctly. No fault codes and nothing out of the ordinary.

I took the car back to the smog check station and it failed the emisions test miserably! I'm not sure how it could easily pass the emissions test with base oxygen sensors and fail miserably with good oxygen sensors but I'll just have to accept it. Anyway, the tech said the cats are both shot.

I called around to some of the local muffler shops and they all told me that these cats are strictly a dealer item and could not be gotten aftermarket. BTW, I'm in California since that appears to make a bit difference here.

So I guess my question for the group now is whether this is true, do I have to get the new cats from the dealer? If not, can anyone recommend a good place to buy them? (I can install them if no welding is required.)

Thanks,


Don

 

Don,

I've had three Montero Sports, all in California. The last time I had a cat fail in my 1999 Limited I searched around for an aftermarket replacement. That was before CVC Sections 27156 & 38391 went into effect on January 1 of this year. Even then I couldn't find an aftermarket direct fit replacement but now you cannot buy a catalytic converter in California simply based on gross vehicle weight, engine size, physical shape, size, configuration, or pipe diameter. It has to be a converter made SPECIFICALLY for your year and model vehicle to meet California OBDII regulations and it has to be listed in the California replacement converter database that the California Air Resources Board generates as a result of compliance certificates issued to converter manufacturers as they complete their compliance testing for each application.

As far as I know, only the original equipment Mitsubishi converters meet this requirement. I know of none in the aftermarket for the Montero Sport that are CARB compliant. You'll find plenty on-line that are "49 State compliant" but they cannot legally be shipped to a California address. Anyone who sells you a non-compliant converter in California faces stiff fines so while there may be some sort of underground supply chain for these, you probably aren't going to find anything from a legitimate auto parts supplier. It is also illegal to advertise or sell used catalytic converters in California so that isn't a very useful path to pursue either.

Pretty draconian. "Velkome to Kalifornia".

 

Don:

Curious as to why the 421 code (rt. pre cat failure) went away and why you don't also have 431 (left pre cat failure) if the tech says they're both bad. Did his scan tool show any codes?

Anyway as I mentoned before, I had the dealer replace my rt side and paid full boat. When the left side went recently I went to a local (non-chain) muffler shop - the kind of place that does custom hot-rod systems - and he said that they were now making tiny pre-cat modules that he has had success installing into the OEM manifold with cut and paste welding. I doubted that could be done judging by the complexity of the design but he was confident - and claimed that the supplier of these things had CA approval for most vehicles. He wanted $375 total for the project.

I was tempted but in the end decided to pay $530 for the factory part (discounted from $700+) and do the labor myself. The extra $155 seemed worth it to insure there were no problems.

You may be able to find a similar shop in your area but I'd recommend going to www.mitsubishiparts.com if you want the correct parts at a good price. (don't forget to order the manifold to downpipe gaskets)

Good luck.

Ron

 

we charge $50 to read and erase codes on any mitsubishi vehicle. diagnosis of the codes is of course extra.

 

challenger4x4: I did contact several large shops that specialize in custom made exhaust systems and they were the ones that told me the cats were not available for my car. If you've have some luck in that area I'll try a few more shops.

jrmdir: The tech actually said "the cat is bad" but was not specific about which one. I don't know how one could find out easily since they are in the downpipes and come together into a single exhaust farther back. If only one is bad, how do I figure out which one it is? When I took the car back after replacing the oxygen sensors there were no fault code anywhere but the tech said the cat showed up as "yellow" in the scan which means that it's "questionable" (his words). Since it failed the emissions test badly one can only assume that one or more of the cats are bad.

I went to the link you supplied and there are 3 cats for this car! There is one in each downpipe and one "rear" cat. The downpipe cats are $604.68 each and the rear cat is $832.49! That's $2,041.85 (plus tax & shipping!) for all 3 pieces! OWW!!!

jgbrules: $50 to read and reset the codes? Isn't that a bit steep for a 5 minute operation? When I was a mechanic, we used to do things like that for clients wthout charge to build good will and wound up with more clients that we could handle. Do people a favor and the often bring their cars back when they need some work done.

Costco is stocking a read/reset tool right now for $35 which I bought.