What else when going to LT headers?
Thread Starter
Drifting
Joined: Jan 2006
Posts: 1,740
Likes: 2
From: Winchester Virginia
What else when going to LT headers?
I'm wondering if the O2 sensors should be replaced with new units on the new exhaust? I saw a few post awhile back talking about a 3-wire O2 sensor, but never got the full scoop on that mod. What else should I consider changing out besides the Cat?
R/Noland
R/Noland
Safety Car
Joined: Jan 2006
Posts: 3,566
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From: Mt Laurel NJ
St. Jude Donor '06-'07
When you install your headers, you should use a heated o2 sensor. This is because the headers run cooler, the unheated o2 sensor will not get hot enough to go into closed loop. I believe you only need to buy a heated sensor from any large GM car.
Hope this helps
Randy
Hope this helps
Randy
Racer
Joined: Sep 2002
Posts: 407
Likes: 0
From: Alma AR
When you install your headers, you should use a heated o2 sensor. This is because the headers run cooler, the unheated o2 sensor will not get hot enough to go into closed loop.
Would this still be true if you install ceramic coated headers?
Would this still be true if you install ceramic coated headers?
Melting Slicks
Joined: Aug 2003
Posts: 3,401
Likes: 396
From: Lakeville MI
With an unheated O2 sensor and long tube headers it is likely that the ecm will drop out of closed loop control at idle or under very light loads.
During normal cruise the ecm should stay in closed loop even with an unheated O2.
This is only a problem if you have a poor open loop calibration at idle.
If you do wind up with problems during open loop idle, you have a few options available in order to remedy the situation.
Heated O2 sensors, adjustable fuel pressure regulators, or custom chip tuning are readily available.
A heated O2 sensor is not really a substitute for proper tuning and is really quite unnecessary with a good tune, unless idle and cold start emissions are a priority.
During normal cruise the ecm should stay in closed loop even with an unheated O2.
This is only a problem if you have a poor open loop calibration at idle.
If you do wind up with problems during open loop idle, you have a few options available in order to remedy the situation.
Heated O2 sensors, adjustable fuel pressure regulators, or custom chip tuning are readily available.
A heated O2 sensor is not really a substitute for proper tuning and is really quite unnecessary with a good tune, unless idle and cold start emissions are a priority.
Team Owner
Joined: Sep 2001
Posts: 62,160
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
3-wire (heated) sensors are not required, and even less so with ceramic coated headers where the heat is retained inside the pipes better.
In normal operation the regular sensor would only drop out of closed loop at idle, mine hardly ever does even that.
In normal operation the regular sensor would only drop out of closed loop at idle, mine hardly ever does even that.
Team Owner
Joined: Sep 2001
Posts: 62,160
Likes: 1,733
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
No other reason in particular, my fuel mileage was fine before the headers.
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Le Mans Master
Joined: Feb 2000
Posts: 9,715
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From: Kempner Texas
One goes to ground, the second goes to a switched 12 volt source (only hot when ignition is in "run" position) and the last one ties in to the factory 02 harness.
Two wires are white and the third is black. The two white wires are for ground and the 12 volt source; the black splices into the wire leading to the stock, single wire 02 sensor.
Jake
Two wires are white and the third is black. The two white wires are for ground and the 12 volt source; the black splices into the wire leading to the stock, single wire 02 sensor.
Jake
Safety Car
Joined: Apr 2003
Posts: 3,793
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From: VA
In general, O2S are good for 30-50k miles.
Advanced
Joined: Oct 2003
Posts: 67
Likes: 1
From: Renton Wa.
OEM's went to the heated O2 sensor because it gets the engine into closed loop faster at cold start up. O2 sensor needs to be at a certain temp before it will work, unsure what that temp is, I used to know it, 600F? So depending on where you mount the sensor in the header collector and what temp it is there would determine if you need one.
Le Mans Master
Joined: May 2000
Posts: 7,033
Likes: 12
I have MANY datamaster logs that would disagree with you. I have TPiS headers and it always has gone into closed loop and the only time it comes out is when I turn the car off for a while and start it back up. There's a trick you can do without datalogging to see if your O2 is going into closed loop, right Ron?
Do you need a new O2? Depends, is your old one bad? If not then I wouldn't replace it.
Drifting
Joined: May 2003
Posts: 1,979
Likes: 48
From: Lakeport CA
I ran a stock O2 in my TPIS LTs for many years before going to a heated one. Didn't really make much diff... well except the heated one failed after about 25K miles & I had to replace it.
I'm still running a heated one & I also have a heated wide band on the other header now that I plug in for testing & confirmation of how my tune is holding up.
IMHO, replace the stock one w/ another stock one after a few K miles. As also stated above, fresh headers & gaskets "may" kill an already tired O2 sensor. If I had it to do over, I wouldn't upgrade to the heated, just an extra hassel & if I need one on the road, it often isn't a simple plug & play like it was. I will be fixing that shortly but it was a lesson learned to use the correct factory connectors & in the correct configuration. I now have the male where the female should be. oops
Thread Starter
Drifting
Joined: Jan 2006
Posts: 1,740
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From: Winchester Virginia
Thanks for all the input, now I have a much better idea of what needs to be done. I'll find the copper gaskets and just replace the stock O2's as an insurance policy. I'm sure it can't hurt anything and after 100K or so, it just makes sense!
R/Noland
R/Noland