I have a stock b16 that has just gone though the original OEM and two magnaflow catalytic converters. I'm assuming it's my burning 1qt every 1500 miles that's killing them. I've replaced the primary and secondary O2 sensors after the first one died. I get pretty good mileage. No blue or black smoke out the tailpipe. Is there anything else to check before considering doing a full rebuild? Only other thing I can think of is my short daily commute isn't letting the cat warm up fully.

 

Leak/compression test. That's what everyone would suggest. Don't drive it because you're just replacing parts. It's already expensive.

 

Forgot to mention the replacements seemed to last about 15,000 mi each.

I've already done compression testing and it came out fine. What are you suggesting that the leakdown will tell me?

 

Raw fuel is what normally destroys cats. So you might be running too rich. But you do say your getting good gas mileage. So how many miles per gallon are you getting? Is the fuel system stock or have you upgraded anything?

 

Glad someone brought that up because I've heard the same about fuel killing converters.

It's completely stock except for an AEM short ram intake. Fuel filter has been changed on the intervals. Ignition system is healthy with relatively new cap/rotor and platinum plugs.

I get about 24 city and 30 highway, but I'm not sure how much my mpg would go down if I had a leaky injector. If it's only 2 mpg I probably wouldn't notice. I get a small puff of black smoke if I stomp on it but that's it. When I replaced my muffler, I noticed that the inside of the new piping got black pretty quickly.

When I changed out the converters, the honeycombs looked pretty normal. Not covered in black, cracked, or anything out of the ordinary.

 

That's pretty decent mileage. That is what I get in my gsr. Stock as well other than the normal bolt ons. I'd say take the injectors out one at a time and get a piece of cardboard and check out the spray patern. Be VERY careful as you are having gas spray out. But that would be the only way I'd know to how to check out if their spraying correctly. As for the black smoke thats just probably from the oil your burning as you mentioned, especially in vtec they tend to do that with age. Have you tried using some sea foam to clean out the injectors and such? Stuff works great!

 

you keep getting an engine light?

 

these magnaflow cats are stock replacements not their high flow cats correct? if they are the high flow cats than there is your problem right there. oem cats will work better last longer but thats why they are 4 or 5 times more than an aftermarket replacement

 

Yep, P0420 will get thrown after about 15,000 mi.

The last two magnaflows have been high flows, but something killed the original OEM cat as well...

 

how many miles where on the stock one? being obd2 is going to be really picky with them too. if you want my advice spend $4 on the cel eliminator off of almost any website. works on my buddies s2k with a test pipe and full exhaust

 

About 100,000 mi, but who knows if it only took 10,000mi of whatever's off to fry it.

Will cell eliminators work in inspection states?

 

if your timing and all is good like you say.

replace the cat with a oem cat and replace both o2 sensors with oem ones from hondA.

had this same problem at my shop. and this is wat i changed to finally fix it. it could be that you have 2 upstream sensors. sound stupid but its possible. especially if you bought universal o2 or from autozone...

 

What type of oil are you running.