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O2 Sensors and Dual Exhaust???

7K views 8 replies 2 participants last post by  **DONOTDELETE** 
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#1 ·
I'm putting a 94 5.8L in a 70 Bronco. On the stock exhaust on the 94 there is a "Y" pipe with an O2 sensor mounted on a small pipe between where the two arms of the "Y" meet (if that makes sense). What I was wondering is if I want to put in dual exhaust, do I have to have a H-pipe with the sensor on it, can I run dual sensors (if so, how would that wire in?), or can I just run with the sensor in one pipe (I'm assuming no, because then it would only get half of the exhaust and then run to rich)? I desperately need help on this one. Oh yeah, does anyone know if 5.0 exhaust headers work on a 5.8? Are there any differences? Thanks for any help guys.

 
#2 ·
Well, I know that the 5.8L exhaust manifolds on a '96 are different than whats on a '90. The differences being 1. the 96 has egr air injection tubes going into each manifold and the 90 doesn't it has the air tube going into the cat. 2. the angle on the passenger side manifold on the 96 is different more of a 45 degree than a 90 degree angle. I'm having problems putting a 1996 5.8L into a 1990 bronco that had a 5.0L. The alternator is different, distributor is different more headaches than I realized. More expensive too.

Backyard Builder-If I ain't drivin it I'm under it!
 
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#3 ·
You can just run the O2 sensor off one bank. Keep it close to the collector so that it stays hot. It doesn't measure the amount of exhaust, just the amount of oxygen in it. The other bank will go unmeasured, which is fine because the computer or injection system isn't accurate enough to adjust for each cylinder.

If it ain't broke, I can probably still fix it.
 
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#4 ·
Thanks for all the help so far, I guess I have the egr tube that connects to the exhaust right after the first catalytic (at least I assume that's what it is). There are two cats, one right after the O2 sensor mini h tube and one after the egr pipe (the egr tube is approx. 3/4" diameter aluminum pipe with a small collecter/bulb(?) at the end with rubber hose connected to it). If I run dual exhaust with one sensor attachted after one of the collectors, do I need to worry about this egr tube? Where should I have it installed. By the way, I am not going to be running cats nor do I need to worry about being smog legal, so if I can get rid of it without affecting performance, that's fine to. Thanks.

 
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#5 ·
The little bulb that connects the rubber hose to the metal tube is actually a one way check valve. There is a little diaphram in side that allows to blow through into the exhaust, but not let exhaust come back up the tube. Where does that metal tube connect to the exhaust? Just on the pipe or does it connect into a catalytic converter?

YOu can do a couple of things:

1.Connect the tube straight to the exhaust pipe.

2.Remove the metal tube and let the hose blow to the atmosphere.

3.Remove the entire EGR system, but that will push a code to the computer.

I would personally choose 1 or 2. With 1 being the the better bet.

Eric


If it ain't broke, I can probably still fix it.
 
#6 ·
Re: EGR tube

That's actually the "thermactor air" tube - thermactor is the $100 word for catalytic converter. When the diverter valve near the air pump is activated to do so, air is pumped thru the check valve down that pipe and into the exhaust stream to react with unburned gasoline as it passes over the catalyst. So if you don't have a cat, you don't need to pump air down there.

BUT !!!!!! All that unburned (hydrocarbons) or partially-burned (cabon monoxide) gas is blowing out your tailpipe for you and the rest of us to breathe. There are emissions laws in most states that require cats (even on aftermarket exhausts) because it's better for everyone. TREAD LIGHTLY If you just HAVE to have that extra 2HP that you think the cats are preventing, get some hi-flow cats. Do it right the first time and you'll be better off in the long run.

I'll get off my soap-box now. /wwwthreads_images/icons/smile.gif

Steve
83 Custom w/95 4.9L EFI, 78 NP435, 83 NP208, 83 D44IFS 3.07, 87 Ford 8.8ABS 3.08, Michelin LTX AT 31x10.50R15
 
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#7 ·
Re: EGR tube

Thanks for all the informative responses. The tube actually connects between the first and second cat. For now, I'm going to have to just hook it up so it dumps open. I would like to install hi-flo cats for the environmental benefits, unfortunately, I'm a student on a budget, and I can't afford the extra 100-150 to add cats to dual exhaust. Quite frankly, those state and federal asses already get too much of my money and determine how it's spent. It is a pre-74 truck (no smog for that in CA) and so I will put cats on when I am ready to and I will do it because I am concerned about the environment, not because they are threatening me with fines.
Sorry, now I will get off my soapbox. : )
Again, thanks for all help, and if any of you guys can think of any other info that is important to swappin in a 5.8 in a EB, it would be greatly appreciated.
 
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#9 ·
Re: EGR tube

It is more than that. Exhaust restrictions on stock vehicles are in the 5% - 7% range. Intake restrictions account for the same (nearly). If I had to do my system all over again, I would have forsaken the freed up power, and kept the emmission equipment on... too late now though.
 
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