My son's car again. A while back Kennin helped me through plugs, coils and evap coils and the car ended up running great again. I learned afterwards though that my son had been driving the car for a couple of weeks with a blinking CEL before he told me it was missing. We had previously spent thousands having all new cat converters put on, but now after the work I did with Kennin's help, we have a code for cat converter insufficiency.

Bigger question though is after months of running great - and it still does - we now have a situation where upon cold start there is a huge smoke cloud spit out. It goes away almost immediately, but happens every time the car is cold.

Any ideas on what is causing this? Also, back to the cats - do we have any options other than replcement again?

Thanks for any help.

 

Misfires are not nice to Catalytic Converters: Read this link Reasons For A Converter Failure .

 

Does anyone have any thoughts on the big cloud of smoke on cold start?

 

Blue = Oil. Black = Rich Fuel.
Keep an eye on your oil level to confirm.

UPDATE: After you confirm oil, You may want to do a compression test (to make sure the engine is still healthy)
Then I would dump the oil and see what, if any, metal particles might be in it.
it might be oil leaking through the valve stem seals or it is piston rings. You must diagnose difference if you can.
Oil is also hard on the catalytic converter.

This is a good read: https://www.mazdaforum.com/forum/maz...ing-oil-28134/

 

i can always tell when someone has no idea what a millenia 2.3 is. compression test? baaahahahaha.

other posters have said the blue cloud symptom is the compressor dying. there are some seals that apparently wear, and oil gets in the intake. i have yet to encounter this problem, and hopefully i never will, so i dont know. under boost, lots of things can happen. i would first check easy stuff, like the pcv valve. then try pulling the intercoolers, and cleaning them. switch to an oil that has additives to soften up seals, and run some good fuel SYSTEM cleaner thru a few tanks of gas. maybe go to a thicker oil, too. and i would like to know if you conquer this problem

on the cat codes, 0421/31, the consensus is that if your car is running good, and getting good fuel economy-which for a 2.3 is around 20 mpg or better, combined city and freeway-then most likely the post cat sensors are too sensitive. this can be solved with spark plug anti foulers, but this is a band aid approach, and might be illegal. the anti foulers can be gotten at any auto parts store for a few bucks. you pull the sensor, put an anti fouler that has been drilled out to about half inch into the sensor hole, then put the sensor into the fouler, erase the code, and it should stay off. however, if your car is getting poor fuel economy, like 16-17 mpg, then most likely your precats are clogged, and you need new ones. but if the car is using oil a lot, new precats will not last a long time. millenias have no resale. if you put money into the car, and you have, you cant get squat for it used. a reman compressor is like 2 grand, and i think like pse superchargers has solved the seal problem. personally, i think bad seals are a result of poor maintenance, and use of junk oil. there is a place in canada that sells the precats for about 240.00

 

First post, lurked for a long time. I have a 2001 Millenia S - Millenium addition. I have a love hate with this car.

Our car - We bought it in 2007 with 30k miles on it and have replaced the transmission once and had it rebuilt under warranty twice(think this was the builder). Supercharder was replaced with a PSE Supercharger. Rear cat. replaced. 2 coils replaced.

I know the front cat. is bad and am going to replace it shortly.

To the OP's original question. I also have the blue smoke. In my case as I have the new supercharge, so I am going to replace valve guides/seals and PCV valve(I have heard that the PCV design can cause oil buildup/burn-off and some have put a filter in-line with their PCV).

Hope this helps.

 

the millenium edition was ONLY my 2000. if your car is a millenium, then it is NOT an 01.
if you are going to replace guides and seals, then you have to pull the heads. you would be way ahead to just get a jdm engine and install it. with all the work that has been done, you probably could have gotten a jdm engine AND trans and installed it, and be way ahead of where you are now. and, just because the compressor is a reman, that does not eliminate it, because new/reman parts can be bad from the getgo. the blue smoke might be deeper than the guides/seals. we have 2 99s'. one we bought new, one used with 60k. both have about 140k, and both do NOT smoke on startup. the black one(bought new) has had synthetic oil all it's life. the white one has had synthetic since we got it, prior to that, it had conventional oil, but changed about every 3k. i would like to know what you end up doing to solve your blue smoke problem, because it seems to be getting a bit more common as the cars age.

 

You are right. Fat fingers on my part. I meant 2000. Haven't thought JDM yet. We'll see. I'll keep you posted.