The headers wouldn't do that. Something has caused the A/F to go waaay too rich.
Header Problem!
Thread Starter
Burning Brakes
Joined: Jan 2003
Posts: 842
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From: Murray KY
Cruise-In VII Veteran
Header Problem!
I have had them for about a month and they are putting black residue all over the back end of my vette and its loading up really bad. Should I try new O2 sensors, any other suggestions? I know a tune is in order but I would like to wait until May for that.
These pics are taken after my vette has been driven 75 miles on dry roads.
These pics are taken after my vette has been driven 75 miles on dry roads.
Burning Brakes
Joined: Jan 2002
Posts: 885
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From: The Woodlands Texas
WOW!
I installed my set of SLP long tube headers and ran the car for about 6 months before dyno tuning but never had that problem and I drive an 01 oil burner.
Are you sure you plugged the O2 sensors back in correctly? Crossing them front to back can cause a fuel ratio problem but I just don't see how you could have done that since the wiring harnesses are different lengths. If the sensors were bad you would be backfiring or throwing codes.
I installed my set of SLP long tube headers and ran the car for about 6 months before dyno tuning but never had that problem and I drive an 01 oil burner.
Are you sure you plugged the O2 sensors back in correctly? Crossing them front to back can cause a fuel ratio problem but I just don't see how you could have done that since the wiring harnesses are different lengths. If the sensors were bad you would be backfiring or throwing codes.
Pro
Joined: Aug 2004
Posts: 575
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From: Richmond Hill Ontario
Are you going full throttle during your drive or just cruising around? If you're only in cruise mode you shouldn't see all that carbon residue as the O2's will still try to keep your AFR at around 14.7:1 even if the headers are letting more air pass. If, however, you are putting your foot into it (WOT) then the fuel system goes into open loop mode and your 02's get bypassed and different tables for fueling come into play and they may need to be adjusted because of your headers. I'd also make sure that all of your ignition wires are on good otherwise you could be getting a lot of ignition misfires and partially unburnt fuel is making it way to the back of your car, thus the black speckles. If this is occurring then it will happen at cruise speeds or full throttle. If you're not getting any codes related to the front 02's or the MAF you probably need to get some tuning done.
Thread Starter
Burning Brakes
Joined: Jan 2003
Posts: 842
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From: Murray KY
Cruise-In VII Veteran
I am not getting on it full throttle, I am usually cruising around. Most of the time it loads up but there is the rare occasion it doesn’t. Most of the time sitting at stop lights the rpms will fluctuate from normal idle to just about to die without touching the throttle. I will check the ignition wires.
Bob
Bob
Are you going full throttle during your drive or just cruising around? If you're only in cruise mode you shouldn't see all that carbon residue as the O2's will still try to keep your AFR at around 14.7:1 even if the headers are letting more air pass. If, however, you are putting your foot into it (WOT) then the fuel system goes into open loop mode and your 02's get bypassed and different tables for fueling come into play and they may need to be adjusted because of your headers. I'd also make sure that all of your ignition wires are on good otherwise you could be getting a lot of ignition misfires and partially unburnt fuel is making it way to the back of your car, thus the black speckles. If this is occurring then it will happen at cruise speeds or full throttle. If you're not getting any codes related to the front 02's or the MAF you probably need to get some tuning done.
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Thread Starter
Burning Brakes
Joined: Jan 2003
Posts: 842
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From: Murray KY
Cruise-In VII Veteran
Le Mans Master
Joined: Nov 2006
Posts: 7,215
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From: Orlando FL
After talking to LG Performance I found out that by running a set of rear O2 sensors on the front following header install will help with the too rich issue. Has to do with the higher wattage. The only trick is the rears are a square plug so you will need an adapter to plug them in. I just put a set of LG long tubes on my car, plugged in simulators for the rear O2 sensors and used a set of rear O2 sensors in the front. works fine. Good luck, that might help hold you over until you get a tune. 
Thread Starter
Burning Brakes
Joined: Jan 2003
Posts: 842
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From: Murray KY
Cruise-In VII Veteran
I may have to try this but I cant find any simulators.
Bob
Bob
After talking to LG Performance I found out that by running a set of rear O2 sensors on the front following header install will help with the too rich issue. Has to do with the higher wattage. The only trick is the rears are a square plug so you will need an adapter to plug them in. I just put a set of LG long tubes on my car, plugged in simulators for the rear O2 sensors and used a set of rear O2 sensors in the front. works fine. Good luck, that might help hold you over until you get a tune.
Le Mans Master
Joined: Nov 2006
Posts: 7,215
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From: Orlando FL
L G Performance 1-972-429-1963 If you are running rear O2 sensors make sure they are hooked up correctly. the rears are crossed right to left and left to right. and the fronts hook up right to right and left to left
If you are running rear O2 sensors make sure they are hooked up correctly. the rears are crossed right to left and left to right. and the fronts hook up right to right and left to left
Last edited by oldschoolvette; Dec 29, 2006 at 06:31 AM.
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Get a tune. Looks like it's running way too rich
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Le Mans Master
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From: Phoenix AZ
If it ran fine before, and after only the header install its now messed up, then it has to be install related. At part throttle the computer will stoich the A/F. Im betting that the O2s are either reversed, not working correctly, or something else related to the install. (loose wire, air leak, etc.)
Pro
Joined: Aug 2004
Posts: 575
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From: Richmond Hill Ontario
If you have an air leak anywhere before the front 02 sensors then you will have the PCM trying to add more fuel to compensate for the extra air being seen by the 02's. Any unmetered air (after the MAF sensor) that's getting into the engine through the intake system or air that's getting sucked in around the header flange or a connection (before the front 02 sensors) will cause extra fuel to be added that's not really needed in the combustion process. A bit of fuel specking is not that uncommon when headers are installed before having a tune done but you've got way more than what would be considered 'normal'. If you find you don't have any 'leaks' in the system then you need to get a scanner hooked up to see how well your 02's are switching. A slow switching 02 sensor will not react quick enough to keep the AFR at the correct stoichiometric value (14.67:1). Off hand, I don't think it probably is a WOT problem as headers tend to lean the mixture out and this would be more evident at WOT when the 02 sensors are not referenced for AFR. Keep us in the loop.