ZedOhSick

Hey guys I have a Z06 with the GT19 cam (227/239 duration @ .050 lift - .678/.688 lift with 1.8 rocker 114 CL).

Car smells pretty rich at idle and I am getting tired of it. Running without cats right now and planning to add high flow cats in a couple days. Hopefully that tones the smell down but I heard that even with cats a lot of the smell will make it through. Save swapping the cam, am I SOL?

racerx3317

That's par for the course with no cats and a cam. Cats will help but I don't know how much

Dan_the_C5_Man

This isn't a "popular" opinion, but I've always thought it was fairly irresponsible to run a street car w/o CATs..

/Soapbox..

That cam looks pretty beefy, and if the car is running in closed-loop (I assume it is), not much you can do (except add those CAT's) - I suppose you could play with injector timing offsets, make sure they are firing on a closed intake valve, but I digress..

And yes, even the CAT's on LT's help, the closer they are to the heads the better.

MTPZ06

Read stuff like this fairly frequent, but then someone will always jump in and say "I run headers, no cats, and the megazilla eco-destroyer camshaft, and I have ZERO gas odor...its all in the tune". I'm guessing its really just the way it is, and some people have a terrible sense of smell. Who knows...

Michael_D

This can be fixed via injector timing, and actually should be addressed when re-calibrating the ECM after a cam change. It is fixed by changing the "end of injection target" to time the eoi to occur after the exh valve shuts.

TRSCobra

How much to fly you to Seattle to tune my car?

blkbrd69

Nature of the beast, I rigged a fan to turn on blowing out of the garage when the garage door light is on.

Helps to turn on recirculate as soon as you start car.

It will change depending on loads and mixes of local gas. Some tanks mine reeks sometimes its not so bad. On alcohol free or race gas it smells great.

Probably not to rich may even be lean? Takes some fuel to smooth out a big cam with a lot of overlap, do have wideband?

Michael_D

I like eating at the Herb Farm.... lol...

I do travel through Seattle often, and would be happy to help you. Or, if you have HPTuners, I could walk you through the tables and help you via phone/email too..... But, I'm not a 'tuner', or a 'professional', so you might be better off finding a 'pro tuner' around your area to work with.

Pinski 1

If you are getting cats just to get rid of the smell,don't bother.... I'm running ARH headers with cats with torquer 110 and I get all sorts of gas fumes.....In fact I just got it inspected and as the car was idling inside the garage plugged into the computer, the tech looks at me laughing with his eyes just about watering from the fumes and says, good thing we arnt in California......

RedZ4me

a rich odor is different from a 'no-cats' odor so are you sure it's a no-cats issue or is it actually too rich?? yes, the cats will mask it somewhat but you may still be rich.

REDZED2

Is it a raw GAS smell or exhaust like no cats or header leak smell?

BearZ06

Tom Wong Performance in Vancouver would be worth the drive.

08mojo

Strange...I went from an off-road arh x-pipe to one with cats. The difference is night and day. Without cats, I would reek of exhaust fumes and my whole house would stink just from parking the car in the garage. The catted x made all the difference and cleaned everything up.

Michael_D

I have ARH LTs with cats on my car. Prior to adjusting injection timing, my eyes would be streaming tears within seconds. Rich, raw fuel smell that would permeate the house for hours. I can now let the car idle in the garage for several minutes. Doesn’t smell like daisies and sunshine, but much better. Fuel trims are also improved under 2000 rpm.

Internets_Ninja

I have the Pfadt LT header and catted X pipe setup. The cats are high flow and small but they definitely help with the odor. On cold start they don't mask any of the smell because the cats have to get warm to function. But once the car warms up there is almost no smell. I can actually use the A/C in non re-circulation mode and I don't get fumes in the car. With that cam you won't get rid of all of the smell but it will make it much better. Unless like other said, you are actually running too rich. Which is a problem and cats wont help that. You can actually damage them if so.

ZedOhSick

Thanks for all the helpful replies. Sounds like there are definitely different experiences out there. I would describe it more as a no cat smell than a pure raw gas smell. There was a delay in the shipment of my catted xpipe so I probably will not get it on until early next week. I will provide an update after I get it bolted on.

A little smell is alright but I don't want my clothes smelling of gas after a couple laps around the block! If the cats do not help me accomplish this I will see if I can find a good tuner to help me out.

Dan_the_C5_Man

You get the initial hit upon cold start-up, but when the CATs heat up the fumes are closer to stock.

norris_83

what he said!

TRSCobra

I'm actually there right now.

Internets_Ninja

Yeah if the smell is that bad you need some tuning. I would raise the idle by 100 RPMs and add 2-3 degrees of timing. Also, check your injector timing, the pulse width could be too long for idle causing extra unburnt fuel.