Disabling catalytic converter warm up. Bad idea?

[Projek01]

With my 3" header back, my car rattles everything in my house when I start it first thing in the morning. I am guessing my neighbors hate me. I find myself letting my car roll off of the driveway so that the ECU detects speed and stops warming up the cats.

From what I read, the car dumps fuel along with retarded ignition timing to blow fuel into the cats. With a new tune, I have a option to remove the cold start cat warm up. The tuner warned me that this can cause premature failure of the cats. What do you guys think?

The way I see it, older cars did not do this and still have functional cats after a lot of miles.

Sometimes I wish I bought the 2.5" setup but the car sounds amazing when its out of the warm up sequence.


Car: FR-S

Mods:
Supercharger
Stock header with cat
2.5" overpipe
3.0" frontpipe with high flow cat
3.0" resonated catback

Let me know what you guys think! Thanks

[RickDaTuner]

The Strategy for cold weather start up on vehicles equipped with variable cam timing has the timing retarded on the exhaust stroke to allow for higher EGTs, fuel delivery really depends on the manufacturer; were some will increase fuel and others will decrease it based on what the precious metal content of their particular cat is, and also on light off times.

Damage to cats will occur when not enough air is introduced into a cold A/F mix, or if the timing is not retarded enough on the exhaust side. The end result is carbonizing of unburnt fuel, which will coat the cat substrate, which then leaves behind varnish and tar, not allowing the hydrocarbons to be broken down and allow the catalyzing process to take place.

You may also find that the car will develop a hard or rough idle when cold.

What you are experiencing in just cold start in general. Based on ambient temperature the AFR is adjusted accordingly (richer as it gets colder), along with a cold engine, its able to suck in cooler and denser air causing the cylinder pressures on combustion to be higher than it would with a warm engine in turn resulting in a bigger bang sound coming from the exhaust.

Removing the cold start strategy may actually make your car louder when cold.

[Projek01]

Thank you for the responce Rick. This is what I found on how other members did to quiet down the car. Do you think it is a bad idea? Maybe I should just leave it and add some sound deadening material in the walls around the car.




High Rev Cold Start noise reduction

Noisy high rev cold start is to warm up Cataylic converters for emissions purposes
http://www.ft86club.com/forums/showp...6&postcount=17


Three things happen Idle is increased to 1700rpm
Additional Fuel is added by offsetting MAF scale during warm-up
Ignition Timing is retarded by 15 degrees during warm-up

The retarded timing is what makes most of the additional noise.
You may get CEL code P050B if so just disable it its due to ecu monitoring post start ignition timing.

To fix alter the “Ignition Timing Post Start” table under “Ignition Timing- Advance” folder .
Change all cells from -15 to -4 degrees and most of the noisy “bark” should be gone.

You can also reduce the “Idle control” “Idle control Target A” and “Idle control Target B” tables reduce the values for idle that are over 1400 rpm to 1400 rpm.

The MAF adjustments can also be scaled back but those tables not in OFT definitions yet

Don’t get to aggressive with your adjustments else your car may not idle well in very cold weather startup and you may also trigger a CEL code related to cat warmup.

Whole thread on it here.
http://www.ft86club.com/forums/showthread.php?t=55676&highlight=high+rev+cold+start

[RickDaTuner]

The added fuel in this car is due to the modded fuel tables from the programer being used, and not a result of the cars actual cold start strategy. There was a huge push for piggy back tuners to curb this kind of stuff from happening, but you never got full control like you do with open source or programers

Easiest way to quiet down a modded car on cold start up is with baffles or silencers, a pain to install and remove, but very effective. Did your exhaust not come with them?

[Twin_Cam_Turbo]

My supercharged BRZ is the same way, it's unbelievably loud when I start it cold but a quick blip of the throttle to 2000rpm or so usually stops the cat warm up procedure.

[Projek01]

No, no silencer as it has "factory look" exhaust tips on it. I even opted for the quieter resonated model.

Doing some research and I want to understand how everything works. This is a little excerpt I found in a magazine.


Extremely retarded ignition timing
during a cold start can increase
enthalpy (specific heat flux as a
value of temperature, mass and
velocity of the exhaust stream) to
the catalytic converter, in the
process shortening the time taken
to achieve full abatement efficiency. "Catalyst heating showcase." Engine Technology International Jun. 2014.

It does make sense that a longer warm up time will allow more crud to coat the surface before it gets hot enough to burn it off. Maybe I will try and find some scientific articles tmw.