Speedforhire

My post cam install (and tuning) is somewhat complete with the exception of WOT tuning. However, the tail pipes are blacking up too much and the gas smell is horrendous. It appears the car is running too rich. Is this customary for a LS3 that is running headers with catless x-pipe?





..............all opinions are welcomed.

telly444

cam, headers, and no cats... I said the same thing to my tuner with my 07 Z. I'm getting a 2nd opinion at my current tune, cause I think it's to rich too. my pipes are black and it stinks like gas too. I was 10.8 at WOT on my wideband.

0Shane@CountyCorvette

Whenever you delete the catalytic converters you're going to see a lot of carbon build up on the exhaust tips with little driving. Even if the engine was running much too lean. If the camshaft is changed to one with plenty of valve overlap 10-20*, you'll certainly smell exhaust gas in the air.

With that being said, you can tone down the exhaust gas smell with proper injector timing. If the injector timing is never changed from factory, then the injectors will open too early during the intake cycle. By spraying the fuel too soon with a larger valve overlap camshaft, the fuel will get sucked through the intake and pushed right out the exhaust before the exhaust valve completely shuts. At that point you're wasting fuel, but could technically not be running rich since this fuel was never even apart of the combustion cycle.

I'm not sure where you're located, but if you would like to have your current tune looked at or have your car re-tuned, I'd love to earn your business. Give me a shout via PM or call the number in my signature. I'll make sure you're taken care of!

-Shane

Speedforhire

Shane;

I'm running +9* of overlap in an otherwise stock LS3 A6 car. It has 1 3/4' headers into a cat-less x and the NPP muffs.

Lance

0Shane@CountyCorvette

Sounds like a stout street friendly camshaft. However, the exhaust smell shouldn't be unbearable. Seems to me the tuner didn't adjust the injector timing.

I received your PM and sent you an email

-Shane

Speedforhire

Idle sound bite:

http://vid1097.photobucket.com/album...pst0zkjxfg.mp4

.............I can't complain about it!

tblu92

The issues you are having are NOT camshaft related but long Tube related
LT's place the front 02 bung up to 3 ft further back-- The stock narrowband 02's are programmed to be accurate only at their stock position--Moving them further aft will make the engine RICH at WOT---- This can be fixed with proper tuning
Also--Many people will install the REAR 02's onto the front locations as a somewhat fix--
The stock rear 02's are more sensitive and heat up better and really help a car with LT's

shawnaj7731

mine is the same way....i think we came to the conclusion we have very similar mods and the exhaust smell is bad but i just use the recirculating inside the cab and get no smell.

tblu92

The only true way to check your WOT fuel accurately is with a "wideband 02"
This eliminates all the guessing and takes the final result ( thru your exhaust ) your engines ACTUAL AFR ratio
YES typically LT headers will make your car run richer at WOT--But it's more complicated than that---A rich WOT is caused by a LEAN P/T AFR--From the added airflow via your cam and hdrs---- At P/T the 02's are correcting for the added aiflow (leaness) via your fuel trims by adding fuel-----
HOWEVER--- whatever your fuel trims are (if positive) "Just before going to WOT" will also be added to your WOT fueling as well--simply as a built in safety by GM----
The ECM will never subtract fuel if you have a negative fuel trim --it will lock on "0" again as a safety at WOT-----
So you must dial in all your P/T fuel before ever attempting to get the WOT fuel near correct----by getting all your fuel trims at P/T at "0" or slightly negative
This is the simple answer however it gets even more complicated --LOL
Whenever you change your engine's Volumetric Efficiency via cams --hds or hrds--it becomes complicated---and only a wideband tells the truth--

C6z06man

What is your cruising AFR?

rio95

Here's a noob question... The lean part throttle condition gets resolved by retuning the maf and VE tables, right? Meaning it shows up as error between commanded Afr and actual part throttle Afr.

Seadawg

Here's something else to check, and it is an easy fix with high temp rtv. Make sure all of your exhaust clamps are sealing the pipes properly, especially the ones near the cats and x-pipe, because if your vette is not in recirc mode on the hvac, you WILL get strong odors inside the car.

Been there and done that immediately after my LT headr install.

Not saying the tune isn't rich too, but this will make it seem a lot worse inside the cabin area.

Speedforhire

Smell inside the car? Yes, it's horrendous also. The LG headers and off-road X fit so poorly, sealing with RTV won't help. I will try it though.

My plan, at this point in the junction, is to return the car back to stock and add a TT kit after winter is over.

More power + less headaches = BLISS!

Modern Musclecar

I have tuned big cam cars to burn really clean with no rich exhaust smell in the past however a tuner will typically intentionally leave the tune a little on the rich side when cammed as it reduces cam surge and greatly improves drivability

1Hotrodz

You should take Tblu's advice, what he says makes complete sense.
Add TT and you will be up to your elbows in tuning and plumbing.

Speedforhire

14.54....................

seevi

That could be a bit lean with a 10% ethical blend.