Ekshail

I'm finally getting to a point where I can start fixing other stuff on my car and I need input.

When I bought the V it already had Corsa exhaust & no cats. No other mods that I know of. So the car is throwing the P0420 code & backfires between shifts. My questions is, is there a way to tell if the O2 sensors are gone or if I'm getting the code because there are no cats?

scatillac

iTrader: (12)

If there are no converters and it's not equipped with "sims" or had the cats deleted during a tune, that's likely where the code is coming from.

As far as the backfiring between shifts, a leaking exhaust can be the culprit. The Corsa clamping system is possibly the enabler here, especially if it was never re-torqued.

It could also be a fueling issue, but your level of mods, it's not as probable unless the tune has been FUBAR'd.

Ekshail

I have a small whole in the intake tube between the MAF & the TB. Could that also cause the "popcorn"?

BudRacing

iTrader: (3)

I've got a resonator delete with an X pipe and electric cutouts before the stock rear mufflers. With the cutouts open it does the same thing. I was thinking this was normal for the stock tune.

KamaSutra

The fuel cuts off on the stock tune when you're off the throttle. This is really noticeable on cold starts or just colder days as the car tends to be rich in that weather. With a non resonated x-pipe and muffler delete, my car tends to do it way more prominently than just muffler delete. It has been getting annoying as of late.

meatyCTS-V

Straight pipes from the primaries back, no codes.

It pops from time to time between shifts. I think it's fun?

-meaty

guitar333

Maybe... I would get it fixed either way. You are dumping metered air which surely isnt going to help.

aurora40

iTrader: (1)

Popping is caused by excess fuel in the exhaust igniting. Cats help consume some of the excess, and a quiet exhaust helps baffle the sound. So you have neither helping out.

It usually happens when you are on the gas hard (car is rich, excess fuel is exhausted), then you let off the gas (car goes into DFCO) and oxygen-rich air is pumped into the exhaust, allowing the fuel to combust.

Personally, I think it sounds badass.

If you tune the car, in addition to tuning out the checks for cat efficiency, you can have DFCO tuned out, and it should eliminate most or all of the backpopping.

Ekshail

@Kamasutra - YES! In the morning it's the worst. I don't even have to get on it, in order for it to pop.
@Meaty - You're tuned right?
@Guitar - Gathering parts as we speak
@Aurora - That's what I figured

So the conclusion is - live with it or get a tune? Can it be tuned with a bad O2? I would assume no. I just don't want to schedule a tune & then find out I need O2's.

meatyCTS-V

If I am, it was done by the PO.

Other than everything being cut-out, I have no idea what else has been done to it, and haven't gotten under there to see if there's simulators or not *shrug*

-meaty

siggyfreud

iTrader: (1)

You'll want to fix that. Un-metered air is a no no.

vmapper

iTrader: (8)

short answer : no. - for many reasons.
unmetered air is handled via adaptive idle, skewing the tune with STITs and LTITs, then your Maf curve and ve table will be 'slightly' off, again, being adjusted by the Fuel trims, and WOT will again be slowly adjusted based on trims.
Me personally, never have LTFTs on, as over time, will alter your perfect WOT tune. anyways...

Its DFCO - and these MAP Entry and Exit values or via rpm can be altered so it never comes on, though the purpose is to increase mpg. I personally enjoy the sound.

vmapper

iTrader: (8)

Unless running a SpeedDensity tune, then you are correct.

aurora40

iTrader: (1)

Well his car has no cats but still has the 0420 codes being thrown, it probably isn't tuned. And it'd still be unfiltered air, which isn't great.

I think the long and short of it is, if his intake is leaking he should fix it, regardless of the symptoms his car is showing.