Folks with LG, Kooks, Dynatech headers, step inside.
Thread Starter
Le Mans Master
Joined: Jul 2002
Posts: 7,076
Likes: 26
From: Nevada and Florida
Folks with LG, Kooks, Dynatech headers, step inside.
Hey Guys. This if for those who have installed LG, Kooks, Dynatech, or other headers with high-flow cats. I needed your experiences.
I have recently installed LT headers with hi-flow cats similar to Random Tech. On cold start there is a strong smell of raw gas (far worse than with stock cats/manifolds). When hot, no smell. I assume this is normal?
The PCM has not relearned yet and I have not adjusted the IFR, PE tables.
Did anyone lean-out the open loop fuel/air table to reduce this the smell?
TIA
I have recently installed LT headers with hi-flow cats similar to Random Tech. On cold start there is a strong smell of raw gas (far worse than with stock cats/manifolds). When hot, no smell. I assume this is normal?
The PCM has not relearned yet and I have not adjusted the IFR, PE tables.
Did anyone lean-out the open loop fuel/air table to reduce this the smell?
TIA
Team Owner
Joined: Mar 2002
Posts: 47,647
Likes: 1
From: Queens, New York Life begins at 183 mph....
St. Jude Donor '08-'09
I have the exact same thing with my Kooks, high flow cats, x pipe and Z06 exhaust. I actually like the smell of gas when I first turn it on. Its not very strong, just a hint of it in the garage. It never gets into the cabin and once its warmed up, its gone. I am kinda worried about passing the sniffer test but from what I've read, they are switching to a plug in emission test here in NYC next year. The car sounds great and was professionally tuned perfectly so I'm not going to lean out air/fuel just because of some stupid emissions test.
Melting Slicks
Joined: Oct 2003
Posts: 2,834
Likes: 91
From: California
With my LGs I had that smell. Then I went under the car and found that with some heat cycles the clamps weren't all that tight anymore and I had a good sized leak.
I put the Torca wide clamps on the system and torqued them down, repeated about 300 miles later. No more smells.
Remember, when cold the exhaust pipes will contract, making a possible
leak. When you heat them up they expand, and could seal that leak.
This may explain why you only smell it when cold, or it's just the PCM dumping more fuel on a cold startup.... but I don't smell it anymore, with or without the cats on my car.
I put the Torca wide clamps on the system and torqued them down, repeated about 300 miles later. No more smells.
Remember, when cold the exhaust pipes will contract, making a possible
leak. When you heat them up they expand, and could seal that leak.
This may explain why you only smell it when cold, or it's just the PCM dumping more fuel on a cold startup.... but I don't smell it anymore, with or without the cats on my car.
Safety Car
Joined: Jul 2002
Posts: 3,874
Likes: 0
From: Fishing Somewhere Cold
St. Jude Donor '11-'12-'13, '15
How do the exhaust outlets look?? Clean them up and see how quickly they soot up. If you are running extremely rich it will happen quickly.
On the upside.....too rich is a far better condition than too lean while you are awaiing a tune
On the upside.....too rich is a far better condition than too lean while you are awaiing a tune
Last edited by sweetcharity; Sep 23, 2004 at 12:28 PM.
Racer
Joined: Jul 2002
Posts: 267
Likes: 0
From: Minnetonka MN
You need to get EFILive or HP tuners to check your ST/LT Fuel TRIMS as well as read your 02 sensors.
More than likely you need to lean out your IFR table a bit the fine tune your VE tables from there absed on the data that is logged.
More than likely you need to lean out your IFR table a bit the fine tune your VE tables from there absed on the data that is logged.
Race Director
Joined: Feb 2003
Posts: 11,133
Likes: 1
From: ~The DARKSIDE Group~
I have similar set up (see sig below), did you do the LS1 edit to go along with your mods?
Our C5's run rich from the factory, headers and highflow cats make 'em run even richer. You may also not be getting the full potential from you mods. Here are my dyno #'s, before and after. Stock, 303 rwhp; headers and cats 312 rwhp (sensors showing very rich fuel/air mixture); after LS1 edit 336 rwhp.
Our C5's run rich from the factory, headers and highflow cats make 'em run even richer. You may also not be getting the full potential from you mods. Here are my dyno #'s, before and after. Stock, 303 rwhp; headers and cats 312 rwhp (sensors showing very rich fuel/air mixture); after LS1 edit 336 rwhp.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Le Mans Master
Joined: Jul 2002
Posts: 7,076
Likes: 26
From: Nevada and Florida
Originally Posted by DRKNGHT
I have similar set up (see sig below), did you do the LS1 edit to go along with your mods?
Our C5's run rich from the factory, headers and highflow cats make 'em run even richer. You may also not be getting the full potential from you mods. Here are my dyno #'s, before and after. Stock, 303 rwhp; headers and cats 312 rwhp (sensors showing very rich fuel/air mixture); after LS1 edit 336 rwhp.
Our C5's run rich from the factory, headers and highflow cats make 'em run even richer. You may also not be getting the full potential from you mods. Here are my dyno #'s, before and after. Stock, 303 rwhp; headers and cats 312 rwhp (sensors showing very rich fuel/air mixture); after LS1 edit 336 rwhp.
Le Mans Master
Joined: Jun 2004
Posts: 7,155
Likes: 154
From: The Arid Sunny Desert
I am experiencing the same gas smell. I noticed it since the Kooks were installed with the FASt intake & 90mm TB. Also I didn't realize that the car dumps more fuel at startup which may explain why I am experiencing a very rough and erratic idle when cold. Once warmed up the idle adjusts nicely.
Thread Starter
Le Mans Master
Joined: Jul 2002
Posts: 7,076
Likes: 26
From: Nevada and Florida
Originally Posted by Pewtavert
I am experiencing the same gas smell. I noticed it since the Kooks were installed with the FASt intake & 90mm TB. Also I didn't realize that the car dumps more fuel at startup which may explain why I am experiencing a very rough and erratic idle when cold. Once warmed up the idle adjusts nicely.
