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1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks Discuss the Early Eighties Bullnose Ford Truck

LT Headers/o2 sensor problems

Old Dec 26, 2008 | 08:54 PM
  #1  
EffunFiddy's Avatar
EffunFiddy
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From: Lucknow, ON
LT Headers/o2 sensor problems

Hey,
I have an 85 f150 2WD with 5.0L EFI and long tube headers with true duals. I relocated the o2 sensor to roughly the same spot as factory but it was only in the no.4 cylinder tube on the header. The sensor is brand new and whenever i start the truck and run it to temperature it begins smoking only out of the passenger side, the same side as the sensor. I was wondering if i need to locate it to the collector to get a proper reading? I have to removie the headers anyways to sandblast and repaint them because there was rust under the crappy-*** factory paint causing the paint to all flake when i first started it lol. To relocate to the collector i need a sensor extension for the wire to reach and all i can find are ones for 86 mustangs in a set of two since the mustangs have two sensors. I was wondering if the extensions would be the same for mustangs as the f150s? Any help would be greatly appreciated, thanks.
 
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Old Dec 26, 2008 | 09:13 PM
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I can't help you with the wiring, but to answer your first question:

Yes, the O2 sensor should always be in the collector. That way you are sampling the entire bank, not just one cylinder.
 
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Old Dec 26, 2008 | 10:06 PM
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EffunFiddy
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Thanks very much uncle.stosh. Would the current o2 sensor location in the 4th cylinder tube be causing the engine to smoke out of that one side?
P.S. I notcied you're a flareside fan, my truck is also a flareside. I love 'em.
Thanks again
 
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Old Dec 27, 2008 | 06:28 PM
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If the number 4 cylinder was running lean for some reason, the O2 sensor would tell the computer this, and the computer would make the whole engine rich. The smoke you are seeing. Is it black?

Some guys who are messing with their FI engines are just leaving the o2 sensor disconnected. This puts the computer in the open loop mode, where it doesn't look at the O2 sensor for fueling instructions, but instead looks up fueling in tables in the memory of the computer. Your fuel mileage may suffer some if you do this, but you never know till you try it.
 
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Old Dec 27, 2008 | 09:07 PM
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Oh yeah, the smoke was black. It's alot of fuel not getting burned. If it's not the o2 sensor, then I figure it's more than likely a bad plug or two or a bad wire or two. If it's either, they are all getting replaced regardless. The timing isn't exactly spot on either, all of which could i suppose make a difference. I suppose i should try all of these things first and then see what happens. The plugs were old and a little blackened from a vaccum line that was off, which we fixed and the wires, as far as I can see are original. Wouldn't be surprised if it could also use a new cap and rotor too. I'll be replacing all the wires, plugs, cap and rotor with likely some performance ones just for ****s 'n giggles. Just wondering if anybody had heard of this happening before because it's only smoking out of the one side and the whole truck was more or less tore completely apart over the course of last winter and something could have possibly gone wrong in that time, although i hope not. Thanks again for the help guys.
 
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