proper O2 bung location

[Bronco DLight]

Guys-
The mechanic says my "new" 98 exploder V8 is running rich bc the O2 bungs are in the wrong place. I have heard conflicting info. I have two sets of bungs, one set high up immediately where the BCB shorties join to the pipes (that's where the sensors are now) and another set just before the (2 in 1 out) magnaflow muffler. Where should the sensors be?

Also, the magnaflo is far too loud. I bought a walker quietflow muffler but have been told it was too long to fit. I can't reall the model but it is at least 8 inches longer than the magnaflo. Thoughts? Does Walker make a short one like the magnaflo that's quiet?

 

[lonesouth]

everything I've read suggests about 4" below the collector of the manifold/header.

 

[Broncobowsher]

12 o'clock ±90° as well. Minimizes condensation issues.

 

[yakelys69]

Is it being said its running rich due to the plugs or the smell? I think without a catalytic converter you always have more of a smell.

 

[pcf_mark]

How many wires does the O2 have? If 4 then it is heated and can work anywhere in the exhaust it does not need engine heat to warm it up to operating temp. As someone said - is it reading rich or smelling rich? I can lean a car all the way to 16:1 and you can still smell something because we do not have cats.

 

[Bronco DLight]

the proximal ones are at 11 and 1 oclock...

the proximal ones are at 11 and 1 oclock and the more distal ones are almost right at 12 oclock. I'll have to check on wire number later. In regards to "richness" I haven't pulled the plugs. Smells rich, sounds rich, EATS fuel. Don;t expect it to be an EPA pleaser but I am filling up a 23 gallon tank very frequently.

But mainly it smells crazy rich, even given the absence of the cat.

 

[Joker11]

Exactly why I want to run full emissions on my Exploder swap. The fumes trigger my wife's migraines.

 

[EFI Guy]

You want the o2's close to the collector and close to 12 o'clock. But, the placement will not have as drastic of an effect as what you are describing.

A leak in the exhaust system before the O2 will cause the PCM to think that its is lean so it will add fuel and make it rich. If you have a problem causing a rich condition like high fuel pressure or a ruptured FPR diaphragm then the PCM will intentionally try to lean it to compensate. The PCM can only compensate so far before it throws a code.

You really need to look at your fuel trims to determine the best course of action.

 

[Bronco DLight]

You want the o2's close to the collector and close to 12 o'clock. But, the placement will not have as drastic of an effect as what you are describing.

A leak in the exhaust system before the O2 will cause the PCM to think that its is lean so it will add fuel and make it rich. If you have a problem causing a rich condition like high fuel pressure or a ruptured FPR diaphragm then the PCM will intentionally try to lean it to compensate. The PCM can only compensate so far before it throws a code.

You really need to look at your fuel trims to determine the best course of action.

Thanks, Gary. I'm out of town but as soon as I get back I'll give you a call if I still think it's a problem. I also wanna pull the plugs and see exactly how rich it is.
D