Gauge

iTrader: (3)

Hey all,

I am in the process of tuning my car for the first time. It's not a wild change as the car was originally tuned by a shop using a 1-bar MAF tune. I have since put a 3.3-bar MAP in the car and am working on an SD tune. The tuning seems to be going well, and I feel like I have a firm understanding thusfar.

I've found something strange, though. When I make a WOT pull, after I let off I can very clearly smell something that kind of smells like sulfur. It smells just like someone lit a match and blew it out in my car. This is making pulls to about 5k (maybe 10psi) an a stock cube LS1. According to my logs, the AFR is around 11.2:1 for the whole pull. It wavers some, but never by more than +/- 4%. I have pulled 30% of the timing out of the spark table that was in my original tune, so the car is running on very little timing right now. Also, the car has metallic substrate cats that have about 3k miles on them.

Can anyone tell me what this might be? I have no signs of knock, lean or rich condition, but it is still worrying me. This is absolutely not my imagination.

Funkster

iTrader: (97)

I have read of people having issues with fuel that will cause this smell. Try changing to a different station and see if it gets any better?

Funkster

iTrader: (97)

I have also seen people complain of the smell when they have a power steering leak.

Carl at CRP

iTrader: (9)

You are describing the smell of the cats.
Carl

SilverSS

iTrader: (30)

+1 on cats. Stock cars WOT do that too just not as noticeable.

Bob@BruteSpeed

iTrader: (16)

I agree, back in 1975 when our government first mandated cats, the sulphur/ rotten egg smell use to be quite common. Anyone as old as you and I are know this smell very well. Bob

Gauge

iTrader: (3)

I'm glad to hear that. I figured if it was anything, it was either the cats or something next to the exhaust burning, but that would sure be a strange smell to come from the clutch hydraulic line or anything else routed near the header.

I'm surprised that the metal cats make that smell. I would expect that to be isolated to ceramic cats. Thanks, everyone.

pwrtrip75

iTrader: (8)

It doesnt matter what the material is made of. Metal, like the ceramic, just holds the coating of catalyst on it Whatever catalyst substance is used....platinum, palladium, rhodium or whatever...

Gauge

iTrader: (3)

Really? I didn't realize there was a coating. I never really understood how cats were supposed to work. It was always explained to me that they heat up and burn unburnt fuel. I never understood how the cat did that. It only gets as hot as the exhaust gasses. If they're not hot enough to burn the fuel, then why would the cat be?

I assume that it's worse than I'm used to because the blower probably increases the EGTs a great deal.

Bob@BruteSpeed

iTrader: (16)

The catalyst is usually made up of small pieces of palladin, a heat-reactive element that turns glowing hot when heated. When functioning correctly they get much hotter than the rest of the exhaust system, which is why there are shields above them from the automotive manufacturers. Bob

Chicago TDP

iTrader: (3)

Meow....

TurboAv

iTrader: (6)

My 83 Bronco does this smell after a trip of more than a few miles. Most noticeable for a few seconds after coming to a stop.

dschmittie1

iTrader: (64)

They still stink but only for the first 5-10 miles. I work at a Dealership and drive cars that have 1 and 2 miles on them all the time. And the exhaust always sticks bad the first time you go out and drive it