Anyone having O2 sensor problems with headers?
Thread Starter
Racer
Joined: Jul 2005
Posts: 412
Likes: 1
From: Champlain New York
Anyone having O2 sensor problems with headers?
To be up front, I am installing a 90-92 TPI Speed Density in my 33 Chevy coupe. I found that the Headman C4 headers fit the car great and give me perfect ground clearance.
In "theory" the O2 sensors should be located approx 12 inches of the heads?..the Headman headers have the O2 bung about 2 feet downstream. Before I mess with a 4 four wire modification (heated) O2 sensor...just wondering if you folks with C4 TPI engines and single wire O2 sensors are experiencing any problems with aftermarket headers.
thanks
In "theory" the O2 sensors should be located approx 12 inches of the heads?..the Headman headers have the O2 bung about 2 feet downstream. Before I mess with a 4 four wire modification (heated) O2 sensor...just wondering if you folks with C4 TPI engines and single wire O2 sensors are experiencing any problems with aftermarket headers.
thanks
Thread Starter
Racer
Joined: Jul 2005
Posts: 412
Likes: 1
From: Champlain New York
nate23..
Thanks..I'm just going to mock up the driveline with a single wire O2 for now.
I'll worry about the O2 situation when it hits the street next Spring. Emissions and CAT will be eliminated..and I may install another single wire O2 on the passenger side collector with a toggle..so I can monitor either side.
Thanks..I'm just going to mock up the driveline with a single wire O2 for now.
I'll worry about the O2 situation when it hits the street next Spring. Emissions and CAT will be eliminated..and I may install another single wire O2 on the passenger side collector with a toggle..so I can monitor either side.
Race Director
Joined: Sep 2003
Posts: 16,838
Likes: 341
From: Database Error Indiana
It was OK in town, but 2 times on road trips, 100 miles at 75 mph. the O2 sensor fouled. Can not explain the why (maybe at steady cruise the O2 did not stay hot enough?) and only know that the heated sensor has never failed.
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Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
When the pipes cooled off at idle, the unheated O2 on my headers ( 9" from collector flange ) dropped out of closed loop .
Would not heat up enough to go CL at cold start idle.
FWIW;
The heated sensor for my WB installed on the test pipe in place of the main cat works perfect all the time.
Would not heat up enough to go CL at cold start idle.
FWIW;
The heated sensor for my WB installed on the test pipe in place of the main cat works perfect all the time.
Last edited by rodj; Aug 12, 2008 at 07:01 PM.
Melting Slicks
Joined: Feb 2006
Posts: 2,753
Likes: 15
From: backwoods upstate ny
where you are you will get better operation with efi/headers using a 4-wire heated sensor (from a 96 chevy corsica or many others)...4 wires are better than 3 due to dedicated ground wire on 4-wire, rare backfeed on 3-wire system due to poor ground will confuse the ecm.
Race Director
Joined: Sep 2003
Posts: 16,838
Likes: 341
From: Database Error Indiana
Melting Slicks
Joined: Feb 2006
Posts: 2,753
Likes: 15
From: backwoods upstate ny
imagine bunches of electrons being fed into the "heating" element of the o2 sensor at 12v, all looking to go to "home ground" thru the single "ground' wire of a three wire assy...NO wire is a "perfect" conductor, and that "ground" wire has "some" resistance -- so some of your "electron crowd" will find another route to "home" = the "signal" wire from the sensor "working stuff" to the ecm that is "supposed" to show the ecm between o.2 to 1 v...can/does happen, ecm is baffled, maybe even "smoked" by excessive "signal" voltage if that "single" wire is high resistance due to breaks in the conductor or corrosion at termination --similar prob is why your instrument panel lights have a "separate" wire from gauges, and why the 4-wire o2 sensor with separate dedicated ground wires for heating and for signal is best.
Safety Car
Joined: May 2003
Posts: 4,283
Likes: 0
From: Houston Texas
Nope, when I used stock computer had to go to a 3 wire to stay in closed loop. On start up and periods of idle, it would go open. Never had a problem with 3 wire and my computer. Extremely easy to wire up. Black wire goes to computer and either white wire goes to switched power source and the other to ground.
Le Mans Master
Joined: Apr 2005
Posts: 6,413
Likes: 9
From: The Old Dominion
FWIW, the LT5 came with three-wire heated O2's.
