Strong exhaust

**LS1 oldtimer** · 11-15-2010, 09:04 AM

When I purchased this car the previous owner had created his own "tune" using the diablo sport tuner. The car ran very well but has very strong smelling exhaust like it is running rich. Since then i have tried the diablo tune and am now running what is supposed to be the stock tune and the strong "rich" smell is still there. The car has long tube headers and a SLP catted y-pipe and Magnaflow exhaust. Any ideas on why it is not burning clean?

**c5z28** · 11-15-2010, 09:17 AM

I am not aware if the diablo tuner can tune a car properly that has headers. Either the cats are inefficient and more likely you will need a tuner to solve your issue.

**PFM** · 11-15-2010, 09:21 AM

Sounds like he gutted the cats out. He probally left the cat cases intact so it looks like it still has cats so it passed visual inspection.

**JRENIGAR** · 11-15-2010, 03:37 PM

The diablo tuner can add or remove fueling in the tables but its strictly wot fueling that it controls. I just got a tune from Frost and use the tuner for clearing codes and such. BTW the Frost tune was WAY better for power and idling qualities with boltons.

**LS1 oldtimer** · 11-16-2010, 03:44 AM

Someone told me yesterday that with the long tube headers the cats were too far back to get hot enough to work. Does this sound right? Also with the Frost tune don't you have to remove and send him the computer? thanks

**cammed goat** · 11-16-2010, 07:20 AM

Yes. You have to remove your computer and send it to Frost. I have never heard of gutting high flow cats. PM Frost and see what he says.

**Cutlass** · 11-16-2010, 06:05 PM

A good tune will solve most of your rich exhaust smell. I recommend Frost. I don't have cats and my car doesn't smell rich.

**666ws6** · 11-16-2010, 07:09 PM

Just keep in mind, a rich exaust smell doesn't necessarily mean you are running rich. Could be a leak, could be burned out cats, gutted cats, etc. A tuner can tell if you are running rich though, and it's a great way to get to know how your new car is really performing.

**RyanJM** · 11-17-2010, 12:57 AM

First check your exhaust for any leaks where the headers meet the cats and y pipe and where the y meets the muffler a leak in that area will make your car smell rich inside while stopped also check the header gasket area is another leak that will create a strong odor. After that the only thing left is the tune.
The old headers I had had a leak at the gasket then I needed new gasket so I installed better headers, ORY, and catback. Only smelled strong at the back after my tune fixed the last shops crap tune you could hardly tell i had no cats. A few months of banging the ORY knocked it loose from the headers so we pushed if foward reclampedit and tack welded a few spots and it was all good again. With high flow cats you will get more odor than a factory setup but shouldn't be as bad as you.say.
So check for leaks since all you need is a jack and opening the hood of you find nothing wrong get it tuned by frost or a local shop that has a wideband 02 so you can see what your a/f is before and after the tune.

**LS1 oldtimer** · 11-17-2010, 08:59 AM

Thanks for the replies! I have looked for leaks and haven't found any at ilde but sometimes during hard exceleration it sounds like there could be a leak up front. This only seems to happen for a split second and when it is not completely warmed up. The smell that i am talking about is coming from the tailpipe and is quite strong. I've a number of people comment about it. I will deffinately be looking at getting a tune, just not sure about sending my computer across the country. With Frost, the price is right though.

**blue02Z** · 11-17-2010, 07:18 PM

Originally Posted by LS1 oldtimer

Thanks for the replies! I have looked for leaks and haven't found any at ilde but sometimes during hard exceleration it sounds like there could be a leak up front. This only seems to happen for a split second and when it is not completely warmed up. The smell that i am talking about is coming from the tailpipe and is quite strong. I've a number of people comment about it. I will deffinately be looking at getting a tune, just not sure about sending my computer across the country. With Frost, the price is right though.

Frost is grade A ole son. he wont jerk you around. i have a dyno tune and i am thinking about sending my pcm off to him cuz i know its a weak tune.

also... what kinda fuel you running? any fuel adders? i know in my old '74 c10 if i put a certain fuel adder in it the exhaust smells like pew. are your tips blacking at all? does it smoke at wot???

**LS1 oldtimer** · 11-18-2010, 03:40 AM

i'm running 93 octane pump gas with no additives. The tips do turn black but i haven't noticed any smoking at wot. This car does seem to put out more steam at the tail pipe on cold mornings than others.

**cammed goat** · 11-18-2010, 04:45 PM

Now I am wondering what O2 sensors you are running...if not simulators. If the tune is correct for the after-cat O2 sensors. If you have a tune, you shouldn't be smelling rich exhaust.

**LS1 oldtimer** · 11-18-2010, 06:46 PM

Now I am wondering what O2 sensors you are running...if not simulators. If the tune is correct for the after-cat O2 sensors. If you have a tune, you shouldn't be smelling rich exhaust.

How do i tell?

**cammed goat** · 11-18-2010, 06:49 PM

Most likely, you will have to pull them to see. Never dealt with them personally.

**alelogman** · 11-28-2010, 10:25 AM

When I purchased this car the previous owner had created his own "tune" using the diablo sport tuner. The car ran very well but has very strong smelling exhaust like it is running rich. Since then i have tried the diablo tune and am now running what is supposed to be the stock tune and the strong "rich" smell is still there. The car has long tube headers and a SLP catted y-pipe and Magnaflow exhaust. Any ideas on why it is not burning clean?

Or at the best show a mechanic the exhaust systems.