Warm up cat CEL

[Emode]

Hello,
I have been throwing this CEL a lot lately. Something about the warm up cat not efficient. Usually i just get a front or rear o2 signal code, but recently i have been throwing this one instead. Just today it happened again after reseting it last night. I run a catless system, and i was thinking maybe this has been related to the extreme cold recently. I let my car warm up before i ever drive it as well. Should code this also be fixed by the MIL eliminators?

it is confusing because if the non consistant codes, so maybe someone else as an idea?

 

[jersey_emt]

Well, my guess is that the ECU doesn't see the right reading from the rear O2 sensor...so it throws the O2 sensor code first, because that is the more likely thing to go south.

Then, after a while, it still is not getting the right reading (or any reading at all if the sensor is removed) from the rear O2, it throws the cat failure code....

 

[jersey_emt]

Are you running with the MIL eliminator now? And it's still lighting the CEL?

 

[Emode]

no i am waiting for ions exhaust to get here......*cough*.....*cough*

 

[Bigg Tim]

What's the code? I just started getting P0421 Warm up catalyst below threshold (Bank 1). I got it twice and never got that code before recently. It has been cold as hell here latley. I have only 1 high flow cat on. The second time I got it I had been driving for a while and everything was good and warm. Where do you get a MIL eliminator for the 2nd O2?

 

[prospeed]

http://www.apexr1.com/index.html

 

[Emode]

0421 is the exact code
has happened many times since it got so cold
usually i get 500-700 miles before i thow a light for the 02

 

[Bigg Tim]

Do you still have the first cat in or is it gone too? Do you think the MIL elimintor will work?

 

[ylmazdaspeed]

I thought both cats were on the downpipe and not on the exhaust itself. From your mods list it just shows that you have a 2.5 inch custom exhaust. I'm not too sure why you're getting the code but the MIL elimonator will help if you're getting code P0420. I run a 3 inch system and where I am it's colder then most places during the winter. I've never had a cel pop up at all. Have you taken your car in to be taken a look at. It could be your cat malfunctioning if you still have one.

 

[Prot_ES20]

how/why would you run a car without a cat installed? aren't there pollution regulations?

 

[Captain KRM P5]

how/why would you run a car without a cat installed? aren't there pollution regulations?

yes, removing your catalytic convertors is a federal offense and a violation of state and local EPA regulations. have i ever known anyone outside of california who has gotten a ticket for it? i think one person, tops.

catalytic convertors are restrictive components of an exhaust system. removing them allows a reduction in back pressure, an overall freer flowing exhaust system and for lack of a better term, better engine breathing. this typically equates to more power, better acceleration, etc. it is known to quicken the spool of a turbocharger on a turboed car like the msp.

 

[Prot_ES20]

thx. i didn't know the reason for doing so.

the engine still requires a certain amount of backpressure to run correctly though, right?

 

[Captain KRM P5]

thx. i didn't know the reason for doing so.

the engine still requires a certain amount of backpressure to run correctly though, right?

less on a turbo car, but most people will say that some backpressure is good or you can lose power

 

[ZenProtege]

If you have no cats the o2 sensor will not read correctly. You have no cats so the sensor isn't reading correctly, duh. Don't worry about it. Your 02 sensor is probably working overtime to keep it hot enough for the zirconium stuff to be able to meter your exhaust. Cats build up a lot of heat to aid in catlyizing hyrocarbons. They further 'help' in making temps hot enough for an o2 sensor to read

From what I understand about NA cars some need the backpressure(somthing to do with pressure needed on exhaust valves, idunno)
With a turbo car any backpressure needed is there from the turbo and small diameter piping alone. having a catted exhaust further limits a system that doesn't need it. The exaust turbine spins from having a high pressure system flow to a low pressure.