Exhaust smell
08-27-2017, 07:55 PM
#1
Burning Brakes
Thread Starter
Exhaust smell
Hey Guys,
So a couple years ago I bought a set of lg lt headers with the high flow cats used from one of the forum members. Had them installed by Kevin over at libertyville chevy (because they also have a speed shop that many local members recommended).
So I loved the power that it added and the sound, I have them paired to a set of Z06 ti exhaust. Now usually I drive with the top down and not very long trips but I did notice a smell every now and then, definitely an exhaust smell. Didn't pay too much attention at the time.
So this weekend had me driving from Chicago to Carlisle for the Corvettes at Carlisle event. Ran into some rain here and there so with the top up and my window open, the exhaust smell was very very noticeable and it didn't let up. With the top down you catch the smell but not so intense.
I don't think this is normal, I am running hi flow cats. What should I be checking?
Thanks,
Les
So a couple years ago I bought a set of lg lt headers with the high flow cats used from one of the forum members. Had them installed by Kevin over at libertyville chevy (because they also have a speed shop that many local members recommended).
So I loved the power that it added and the sound, I have them paired to a set of Z06 ti exhaust. Now usually I drive with the top down and not very long trips but I did notice a smell every now and then, definitely an exhaust smell. Didn't pay too much attention at the time.
So this weekend had me driving from Chicago to Carlisle for the Corvettes at Carlisle event. Ran into some rain here and there so with the top up and my window open, the exhaust smell was very very noticeable and it didn't let up. With the top down you catch the smell but not so intense.
I don't think this is normal, I am running hi flow cats. What should I be checking?
Thanks,
Les
08-27-2017, 08:11 PM
#2
Le Mans Master
Thinking just a leak. Get it up on ramps and tighten all clamps etc. Look for black soot at connections. Then run it, get a stethoscope or an inscence stick (anything that creates smoke... I'd recommend a cigarette but I don't recommend smoking 
) and wave it around all connections looking for movement.
These exhausts have a rep for leaking at the midpipe to rear pipe ahead of the axle, good place to check.
) and wave it around all connections looking for movement.These exhausts have a rep for leaking at the midpipe to rear pipe ahead of the axle, good place to check.
The following users liked this post:
ljorges (08-27-2017)
08-27-2017, 09:33 PM
#3
Race Director
Member Since: Dec 2010
Location: Atlanta, GA
Posts: 10,426
Received 1,261 Likes
on
1,056 Posts
2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
lg makes great headers but the clamps they provide with the kit are not the best... I recommend getting some lap band clamps to replace all of the clamps on the system, some like these http://www.jegs.com/i/Dynomax/289/33272/10002/-1 ... you should need 6 to do the whole system and it should not leak anymore
The following users liked this post:
ljorges (08-27-2017)
08-29-2017, 06:01 PM
#4
Burning Brakes
exhaust smell
Depending how strong the the exhaust smell is the c5 1998 vette that I have has a secondary air pump that does fail but your check engine light would have lit up.. You can get a good wiff seating still with the car button up
08-30-2017, 12:09 PM
#5
Racer
This may or may not help, but I too had what I thought was an exhaust leak. Wouldn't smell it so much when driving but at stop lights and when pulling into the garage, I could smell it. This went on for a while, I'd pop the hood and nothing. My oil pressure has always been extremely good and I did end up seeing a couple of dribbles on my garage floor. When my oil light came on I figured it was time to get serious. So I put her up on jack stands and went underneath. I found my exhaust pipes were wet with oil and my oil sensor was leaking not from the threads, but from the body. After replacing the sensor, all is well. Just giving you another place to look.
Last edited by caddman11; 08-30-2017 at 12:11 PM.
08-30-2017, 01:41 PM
#6
Tech Contributor
Member Since: Dec 1999
Location: Anthony TX
Posts: 32,736
Received 2,180 Likes
on
1,583 Posts
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Several years back, I SEA FOAMED my engine by sucking the liquid into the engine from the PCV connection at the front of the intake manifold passengers side (just rearward of the TB Opening.
After sucking down approx. 1/4 of the can and the engine idling around 2500-3000 RPM, I shut down the engine as it was still sucking fluid and let the fluid sit inside the engine over night.
When you restart the engine,,, MAN, does it smoke.
SO, as it was clearing out the Sea Foam from all the cylinders and fumigating the mosquitos several block down the street, I noticed ALL the small leaks in my exhaust system!
TRUST ME! You will see them ALL!
Give that a try and see if you have a leak that is close to the front of the cabin!
Bill
After sucking down approx. 1/4 of the can and the engine idling around 2500-3000 RPM, I shut down the engine as it was still sucking fluid and let the fluid sit inside the engine over night.
When you restart the engine,,, MAN, does it smoke.
SO, as it was clearing out the Sea Foam from all the cylinders and fumigating the mosquitos several block down the street, I noticed ALL the small leaks in my exhaust system!
TRUST ME! You will see them ALL!
Give that a try and see if you have a leak that is close to the front of the cabin!
Bill
The following users liked this post:
mre1974 (11-08-2017)
08-31-2017, 07:39 PM
#7
Burning Brakes
Thread Starter
So an update but not a fix yet.
I took the car to a custom exhaust shop not far from the house. Very well liked and reviewed establishment. So the first thing he asked if I had any check engine lights or codes thrown. There weren't.
He checks it out and he says that the exhaust isn't leaking.
He goes on to say that the smell is coming out of the exhausts themselves. He says it smells like it's running real rich an almost unburnt gas smell. He said that the front o2 sensor was moved to the rear and a simulator Put in front. He went on to Say that high flow cats will never be as good as the stock cats in removing the smell. Even so to him the smell was way worse than it should be.
The car was tuned after the install. Could this be the result of an improper tune? What do you guys think? I can't believe that everyone that gets lt headers and high flow cats have this strong smell.
Les
I took the car to a custom exhaust shop not far from the house. Very well liked and reviewed establishment. So the first thing he asked if I had any check engine lights or codes thrown. There weren't.
He checks it out and he says that the exhaust isn't leaking.
He goes on to say that the smell is coming out of the exhausts themselves. He says it smells like it's running real rich an almost unburnt gas smell. He said that the front o2 sensor was moved to the rear and a simulator Put in front. He went on to Say that high flow cats will never be as good as the stock cats in removing the smell. Even so to him the smell was way worse than it should be.
The car was tuned after the install. Could this be the result of an improper tune? What do you guys think? I can't believe that everyone that gets lt headers and high flow cats have this strong smell.
Les
08-31-2017, 08:07 PM
#8
Le Mans Master
So an update but not a fix yet.
I took the car to a custom exhaust shop not far from the house. Very well liked and reviewed establishment. So the first thing he asked if I had any check engine lights or codes thrown. There weren't.
He checks it out and he says that the exhaust isn't leaking.
He goes on to say that the smell is coming out of the exhausts themselves. He says it smells like it's running real rich an almost unburnt gas smell. He said that the front o2 sensor was moved to the rear and a simulator Put in front. He went on to Say that high flow cats will never be as good as the stock cats in removing the smell. Even so to him the smell was way worse than it should be.
The car was tuned after the install. Could this be the result of an improper tune? What do you guys think? I can't believe that everyone that gets lt headers and high flow cats have this strong smell.
Les
I took the car to a custom exhaust shop not far from the house. Very well liked and reviewed establishment. So the first thing he asked if I had any check engine lights or codes thrown. There weren't.
He checks it out and he says that the exhaust isn't leaking.
He goes on to say that the smell is coming out of the exhausts themselves. He says it smells like it's running real rich an almost unburnt gas smell. He said that the front o2 sensor was moved to the rear and a simulator Put in front. He went on to Say that high flow cats will never be as good as the stock cats in removing the smell. Even so to him the smell was way worse than it should be.
The car was tuned after the install. Could this be the result of an improper tune? What do you guys think? I can't believe that everyone that gets lt headers and high flow cats have this strong smell.
Les
08-31-2017, 08:27 PM
#9
Tech Contributor
Member Since: Dec 1999
Location: Anthony TX
Posts: 32,736
Received 2,180 Likes
on
1,583 Posts
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Unless you have a Speed Density Tune,, YOU MUST have O2 Sensors in the front bungs.. Sims will NOT work.
Figure out how your PCM is tuned and get back to us.
High Flow Cats and a PROPER Tune will get you a pretty clean exhaust smell BUT, Like it was stated, it will never be as clean as OEM CATs
Figure out how your PCM is tuned and get back to us.
High Flow Cats and a PROPER Tune will get you a pretty clean exhaust smell BUT, Like it was stated, it will never be as clean as OEM CATs
11-04-2017, 06:44 PM
#10
My 98 has more of a sulfer smell. Ok when cruising but always bad when under acceleration.
No engine lights, runs smooth? I have a factory exhaust. Are my cats clogged or have bad O2 sensors?
No engine lights, runs smooth? I have a factory exhaust. Are my cats clogged or have bad O2 sensors?
11-04-2017, 07:23 PM
#11
Le Mans Master
Do they have any inconsistency in color?
11-06-2017, 10:46 AM
#12
Instructor
i have the same smell/ issue with mine as well. I was told it was the factory cats are gunked up. I'm dumping them over the winter for some Borla high flows and new cat backs
11-06-2017, 07:01 PM
#13
Tech Contributor
Member Since: Dec 1999
Location: Anthony TX
Posts: 32,736
Received 2,180 Likes
on
1,583 Posts
CI 6,7,8,9,11 Vet
St. Jude Donor '08
There are several emissions products that can help fix the smell issue. Google CATALITIC CONVERTER CLEANING and see what one you want to try:
Here is an article that may help you understand the issue. CATACLEAN has been around a long time and most likely will help:
https://exhaustsystemsguide.com/cata...erter-cleaner/
When was the last time you changed the plugs and wires?
How do you drive the car? 1= Grand Mother Sunday drive - 10 = Rickey Racer Hard on the throttle and wind her out to 6850 RPMs frequently!
Mileage????
Auto or AUTO??????
LOL!
Hope this helps.
Bill
Here is an article that may help you understand the issue. CATACLEAN has been around a long time and most likely will help:
https://exhaustsystemsguide.com/cata...erter-cleaner/
When was the last time you changed the plugs and wires?
How do you drive the car? 1= Grand Mother Sunday drive - 10 = Rickey Racer Hard on the throttle and wind her out to 6850 RPMs frequently!
Mileage????
Auto or AUTO??????
LOL!
Hope this helps.
Bill
11-07-2017, 10:12 PM
#14
Stinky exhaust
There are several emissions products that can help fix the smell issue. Google CATALITIC CONVERTER CLEANING and see what one you want to try:
Here is an article that may help you understand the issue. CATACLEAN has been around a long time and most likely will help:
https://exhaustsystemsguide.com/cata...erter-cleaner/
When was the last time you changed the plugs and wires?
How do you drive the car? 1= Grand Mother Sunday drive - 10 = Rickey Racer Hard on the throttle and wind her out to 6850 RPMs frequently!
Mileage????
Auto or AUTO??????
LOL!
Hope this helps.
Bill
Here is an article that may help you understand the issue. CATACLEAN has been around a long time and most likely will help:
https://exhaustsystemsguide.com/cata...erter-cleaner/
When was the last time you changed the plugs and wires?
How do you drive the car? 1= Grand Mother Sunday drive - 10 = Rickey Racer Hard on the throttle and wind her out to 6850 RPMs frequently!
Mileage????
Auto or AUTO??????
LOL!
Hope this helps.
Bill
I should change plugs and wires as I do not know when they were done last. They are new in look and it runs good and plugs look ok but it is a good point.
I did put a Blackwing on it and it does run better but the smell was there before installing it.
My car is an auto, and it is a car that is driven by both me and my wife. Neither of us drive easy. I kept the miles off the first year but love driving it and I take it everywhere when I’m not working.
I have not checked the color of them? What color am I looking for?
11-08-2017, 02:08 PM
#15
Tech Contributor
Member Since: Dec 1999
Location: Anthony TX
Posts: 32,736
Received 2,180 Likes
on
1,583 Posts
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Pull out a spark plug wire and plug on each bank and see what the plugs look like. Check the gap and look at the color of the insulators.
OEM plug wires are AC Delco black wires with metal shields on the boots.
If you have OEM origional stuff, its a good idea to get some new plugs and wires. I recommend some new AC Delco Irridium plugs and some GM Performance Red wires.
You can also clean the MAF and Throttle body throttle blade while you are working on it.
BC
OEM plug wires are AC Delco black wires with metal shields on the boots.
If you have OEM origional stuff, its a good idea to get some new plugs and wires. I recommend some new AC Delco Irridium plugs and some GM Performance Red wires.
You can also clean the MAF and Throttle body throttle blade while you are working on it.
BC
11-08-2017, 05:00 PM
#16
Le Mans Master
Pull out a spark plug wire and plug on each bank and see what the plugs look like. Check the gap and look at the color of the insulators.
OEM plug wires are AC Delco black wires with metal shields on the boots.
If you have OEM origional stuff, its a good idea to get some new plugs and wires. I recommend some new AC Delco Irridium plugs and some GM Performance Red wires.
You can also clean the MAF and Throttle body throttle blade while you are working on it.
BC
OEM plug wires are AC Delco black wires with metal shields on the boots.
If you have OEM origional stuff, its a good idea to get some new plugs and wires. I recommend some new AC Delco Irridium plugs and some GM Performance Red wires.
You can also clean the MAF and Throttle body throttle blade while you are working on it.
BC
Steel = 0.28#/cubic inch
Lead = 0.40
Iridium = 0.82
Crazy.
11-08-2017, 06:18 PM
#17
Drifting
Several years back, I SEA FOAMED my engine by sucking the liquid into the engine from the PCV connection at the front of the intake manifold passengers side (just rearward of the TB Opening.
After sucking down approx. 1/4 of the can and the engine idling around 2500-3000 RPM, I shut down the engine as it was still sucking fluid and let the fluid sit inside the engine over night.
When you restart the engine,,, MAN, does it smoke.
SO, as it was clearing out the Sea Foam from all the cylinders and fumigating the mosquitos several block down the street, I noticed ALL the small leaks in my exhaust system!
TRUST ME! You will see them ALL!
Give that a try and see if you have a leak that is close to the front of the cabin!
Bill
After sucking down approx. 1/4 of the can and the engine idling around 2500-3000 RPM, I shut down the engine as it was still sucking fluid and let the fluid sit inside the engine over night.
When you restart the engine,,, MAN, does it smoke.
SO, as it was clearing out the Sea Foam from all the cylinders and fumigating the mosquitos several block down the street, I noticed ALL the small leaks in my exhaust system!
TRUST ME! You will see them ALL!
Give that a try and see if you have a leak that is close to the front of the cabin!
Bill
I may need to revisit this with my FRC as I've been getting strong exhaust fumes off and on in the cabin this past summer with the AC on both the fresh air draw and re-circulation settings.
11-08-2017, 09:00 PM
#18
Exhaust smell
Pull out a spark plug wire and plug on each bank and see what the plugs look like. Check the gap and look at the color of the insulators.
OEM plug wires are AC Delco black wires with metal shields on the boots.
If you have OEM origional stuff, its a good idea to get some new plugs and wires. I recommend some new AC Delco Irridium plugs and some GM Performance Red wires.
You can also clean the MAF and Throttle body throttle blade while you are working on it.
BC
OEM plug wires are AC Delco black wires with metal shields on the boots.
If you have OEM origional stuff, its a good idea to get some new plugs and wires. I recommend some new AC Delco Irridium plugs and some GM Performance Red wires.
You can also clean the MAF and Throttle body throttle blade while you are working on it.
BC
I am planning on taking it for the weekend on a road trip. I can do the plugs and wires on Friday Morning, before I leave. I will pick up some car cleaner too.
11-10-2017, 12:34 PM
#19
Tech Contributor
Member Since: Dec 1999
Location: Anthony TX
Posts: 32,736
Received 2,180 Likes
on
1,583 Posts
CI 6,7,8,9,11 Vet
St. Jude Donor '08
The ONLY part of the plug thats Iridium is a very small puck fused to the exposed center electrode. Everything else is steel. Sometimes they fuse a rare metal puck to the face of the side electrode.
BOSH says that they use platinium. LOL. I took one apart to see how much platinum one plug had inside.
$$$$$$$$$$$$$$$$$$$
Well,,,,
The very end of the center electrode has a very thin wire about 1/8" long and part of that wire is platinum. Wasnt even worth the time to fish it out of the trash to examine it. LOL!!
Bill
11-10-2017, 03:26 PM
#20
Race Director
Mine has had an exhaust smell as long as I can remember. I went from an O/R X pipe, to HF cats, and AFAIK, it didn't change the smell. Of course, in my case, I attribute the smell to an aftermarket cam, heads, etc. Maybe it needs to be retuned. but my tuner is 250 miles away.