Headers/duals and O2 sensor?
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Lead Driver
Joined: Jan 2003
Posts: 9,893
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From: Ohio
Headers/duals and O2 sensor?
My '89 has only one O2 sensor but the headers have one on each side. Since I'm running putting on true duals, should I just plug one side?
I've thought of putting a crossover up in the front and putting O2 sensor there, kinda like the stock Y pipe does. Pretty sure it won't really matter.
How has everyone else done it?
Picking up my headers this weekend(got them coated), got exhaust sitting in garage. Just need a couple days to install.
I've thought of putting a crossover up in the front and putting O2 sensor there, kinda like the stock Y pipe does. Pretty sure it won't really matter.
How has everyone else done it?
Picking up my headers this weekend(got them coated), got exhaust sitting in garage. Just need a couple days to install.
Lead Driver
Joined: Apr 2001
Posts: 6,335
Likes: 6
From: Midwest
just use the passenger side bung and plug the other side. The engine will run fine with the o2 sensor reading off one side of the engine. Mine has been that way for three years,and others on here have done it this way also.
Senior User
Joined: Jun 2011
Posts: 382
Likes: 0
From: Milford, CT
Make a crossover tube. It will run with it in just one side, but it will have more power, economy, and will tell you if something is terribly wrong if you have the crossover. For limp home/short term, ok. For extended use, put in a crossover tube before you accidentally burn one side of your engine (much more expensive than a tube).
Bottom line: You don't NEED one, but you should put it in. Do it where the two sides are closest together for best results.
-Mike
Bottom line: You don't NEED one, but you should put it in. Do it where the two sides are closest together for best results.
-Mike
Senior User
Joined: Jun 2012
Posts: 409
Likes: 1
From: Michigan
When I put headers on my '86 they didnt have any bung for the O2 sensor so I bought a weld in bung, and welded it onto the exhaust pipe. I used early factory fox body shorty headers. It runs good with this setup, also has true duals.
Lead Driver
Joined: Apr 2001
Posts: 6,335
Likes: 6
From: Midwest
Make a crossover tube. It will run with it in just one side, but it will have more power, economy, and will tell you if something is terribly wrong if you have the crossover. For limp home/short term, ok. For extended use, put in a crossover tube before you accidentally burn one side of your engine (much more expensive than a tube).
Bottom line: You don't NEED one, but you should put it in. Do it where the two sides are closest together for best results.
-Mike
Bottom line: You don't NEED one, but you should put it in. Do it where the two sides are closest together for best results.
-Mike
Senior User
Joined: Jun 2011
Posts: 382
Likes: 0
From: Milford, CT
Having it in one side will not kill the engine, it just gives you no data on the other bank. You will not be able to chase any codes on that side of the engine that are related to the fuel mixture (which is a lot of them) because there wont be any. It also should not properly meter EGR (IIRC HEGO output is a component of the EGR code), and will not actively correct for any fueling problems on that bank. The computers base almost everything off that HEGO, the ECT, the and the MAP/IAT or MAF sensor. That makes each one very important.
If you have the 2 pipes next to each other for any length of the run (necessary for any dual tankers, or people avoiding the fuel lines), it's easy enough to put it in, so why not?
-Mike
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Lead Driver
Joined: Aug 2006
Posts: 5,670
Likes: 13
From: Sand Lake, MI
Batch fired verses sequential so addition of one for the other side just in duals isn't necessary.
Get a better "over all" picture of the exhaust gases with a single 02 sensor in the middle of an x | h pipe whatever ya wanna call it? yea no one disputing that.
If the motor is in good shape, all cylinders contributing equally don't have one pumping oil or suffering blow by? Then one side will be fine. That and if have cylinder not up to speed, money better spent correcting that first before thinking about adding dual exhaust!
Get a better "over all" picture of the exhaust gases with a single 02 sensor in the middle of an x | h pipe whatever ya wanna call it? yea no one disputing that.
If the motor is in good shape, all cylinders contributing equally don't have one pumping oil or suffering blow by? Then one side will be fine. That and if have cylinder not up to speed, money better spent correcting that first before thinking about adding dual exhaust!
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Posting Guru
Joined: Sep 2008
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The computer in the truck only has one input for an O2 sensor. If you go through the trouble of adding a crossover pipe, the gas that is being sampled by the sensor will be from both sides of the exhaust instead of just one but you will still have only one input into the computer and the computer will adjust the fuel based on that. So the computer will be able to test the gases from both sides of the engine and would be able to adjust better, but you are still running a bank firing system for your injectors so I don't think you'll make much gain from adding the crossover.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
With the batch fired system having the O2 "see" both sides really won't help much, AFAIK the SD computer applies the same injector trims to both batches all the time so there is no net gain/loss with the O2 on one side. With a sequential mass air setup the computer has dual sensor inputs and it's designed to be able to apply different injector maps to each engine bank, but even then if all your squirters are in good shape and the engine has no mechanical issues like a burnt valve or worn rings on one lung then these two maps are going to be very similar so again it's not really worth the effort and expense of installing 2 sensors. I did some experimenting with this on my truck and I saw no difference whatsoever in fuel consumption, power, or engine operation, and I also had realtime data to look at on my Tweecer to compare L and R fuel trims.
Posting Guru
Joined: Sep 2008
Posts: 2,379
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With the batch fired system having the O2 "see" both sides really won't help much, AFAIK the SD computer applies the same injector trims to both batches all the time so there is no net gain/loss with the O2 on one side. With a sequential mass air setup the computer has dual sensor inputs and it's designed to be able to apply different injector maps to each engine bank, but even then if all your squirters are in good shape and the engine has no mechanical issues like a burnt valve or worn rings on one lung then these two maps are going to be very similar so again it's not really worth the effort and expense of installing 2 sensors. I did some experimenting with this on my truck and I saw no difference whatsoever in fuel consumption, power, or engine operation, and I also had realtime data to look at on my Tweecer to compare L and R fuel trims.
Last edited by RIKIL; Sep 7, 2012 at 04:57 PM. Reason: cuz
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