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High flow catalytic converter?

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"Turbo-T"

V6 on steroids
Joined
Jan 10, 2007
Messages
7,393
Ok I know most everyone says "take the cat off and your turbo spools quicker...."

What about a high flow cat? Has anyone tried one? Does a high flow cat slow down spool?

Also are high flow cats good still at filtering out the emissions? B/c every time I start the car it fills the house with emissions, even if I pull the car 10 ft. away. (we have an attached garage) Thinking of my wife and daughter here.

Thanks in advance.
 
The stock one is high flow. No cat will burn off emissions properly till its up to temp. So cold starts will always be rich. I wouldnt worry too much. For years millions of people inhaled a lot of ex emissions and they are ok.
 
I know...the other thing is I can set off every CO2 detector in the house. It's really stinky on start up.
 
I know...the other thing is I can set off every CO2 detector in the house. It's really stinky on start up.
I think you mean CO. There are things you could do to minimize the richness at cold start. Use a block heater and have your cranking and cold start fuel adjusted in the chip. The CTS has a large impact on the cold start. The warmer the engine is the less emissions you will have on startup.
 
Well it's a Turbo tweak 5.7 chip, you say there's a fuel adjustment I can do for cold starts? How? I'm only aware of the WOT adjustment and the WOT in 1st gear one.

You also mention "CTS" I'm gonna guess that's coolant temp sensor? Perhaps there's a way with that to "fool" the ECM into thinking it's warm...just for cold starts only...?
 
Well it's a Turbo tweak 5.7 chip, you say there's a fuel adjustment I can do for cold starts? How? I'm only aware of the WOT adjustment and the WOT in 1st gear one.

You also mention "CTS" I'm gonna guess that's coolant temp sensor? Perhaps there's a way with that to "fool" the ECM into thinking it's warm...just for cold starts only...?
Its adjustable on the burn only. You cant manually adjust it other than dropping fuel pressure but that will be a linear adjust when in open loop. Tricking it will not work since it will be too lean if the engine is not up to temp if the program is close.
 
Another thing I'm interested in is how much would a high flow cat quiet down the exhaust? I'm running a straight shot 3 inch, won't be able to swap out for a while.
 
What shape is the car's EGR and Vacuum system in? That would make more of a difference on cold starts. What does your wide band say at idle? Im thinking your best bet would be to talk with Eric at TT and have a new chip burned with a leaner idle and part throttle.

The only thing I see in your sig that might cause excessive emissions is the cam since it's flowing considerably more air/fuel through the engine at all times. Either way, I dont think you will be happy with a cat if your issues are with the cold starts. Like Bison said, the cat doesn't fire up for quite a while, and it wont work until it's up to temp.

One of the things I did to get through emissions was wrapping my downpipe with exhaust wrap. I had a cat at the time, and the car still wouldn't pass. I got to thinking about it and figured that maybe it needed more heat so I tried the wrap. It made a big difference on my emissions scores! If you do get a high flow unit, you may want to consider either wrapping or ceramic coating your DP to help it fire up faster. Hell I'd wrap my whole exhaust if I wasn't worried about the car bursting into flames from oil soaked exhaust wrap haha.
 
My car no longer has an egr system. Vacuum is pretty good i think. My WB at idle on cold is anywhere from upper 11's to lower 13's.
 
My car no longer has an egr system. Vacuum is pretty good i think. My WB at idle on cold is anywhere from upper 11's to lower 13's.
That actually sounds a little leaner than most ive seen on cold start.
 
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