oxygen sensor wires cut. no code. affecting engine?
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Freshman User
Joined: Dec 2001
Posts: 48
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From: Olathe USA
oxygen sensor wires cut. no code. affecting engine?
my 89' 302 has the three wires going to the front oxygen sensor cut. i am not getting a code, but my truck will billow black smoke above 3000 rpm, and i am getting about 7-10mpg, highway from a half ton. could the sensor be sending a bad signal to the computer even though it is cut, and make my truck run rich? thanks in advance.
Senior User
Joined: Sep 2002
Posts: 321
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From: kansas
oxygen sensor wires cut. no code. affecting engine?
Try not to think of it as the evil sensor sends bad codes to screw up computer. The sensor's function is to adjust a/f ratio to IMPROVE the way engine functions. If you're not getting a malfunction light something else is wrong. It's not even that uncommon for previous owners to pull the bulb out of the light when they can't figure out why it's on.
First find out why light ain't on. And reconnect the o2 sensor.
Second get codes pulled. You can do it with a jumper wire and a good manual. Or Autozone does it for free.
Third address whatever problems are indicated by those codes. Note it's not that simple. If you get an o2 sensor code this means that computer isn't liking the reading it's receiving from o2 sensor. The sensor isn't necessarily the cause. Could be as simple as a vaccum leak. Or as complex as a couple of wiggy sensors making it run rich or lean. Use common sense and deductive reasoning and you'll be okay.
You're reward will be a good running truck and the knowledge neccessary to keep it that way. Good Luck
First find out why light ain't on. And reconnect the o2 sensor.
Second get codes pulled. You can do it with a jumper wire and a good manual. Or Autozone does it for free.
Third address whatever problems are indicated by those codes. Note it's not that simple. If you get an o2 sensor code this means that computer isn't liking the reading it's receiving from o2 sensor. The sensor isn't necessarily the cause. Could be as simple as a vaccum leak. Or as complex as a couple of wiggy sensors making it run rich or lean. Use common sense and deductive reasoning and you'll be okay.
You're reward will be a good running truck and the knowledge neccessary to keep it that way. Good Luck
Post Fiend
Joined: Nov 2001
Posts: 14,947
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From: Topsfield, MA
oxygen sensor wires cut. no code. affecting engine?
A disconnected o2 sensor will make your engine run rich, very rich. I advise that you replace the sensor and fix that issue. The o2 needs to be there so you have to replace it anyway. Replace it, and go from there.
Primary rig is Green Thunder:
95' F-150 XLT 4x4, 302, 5 spd, MSD 6A, Flowmaster Exhaust, Sunroof, Clear corners w/ Diamond headlights, CD player with 2 10" subs and some 32" BFG Muds
.
Thats it for now, saving for a stang. Check out my Gallery for a look-see.
Justin - One Happy FTE Member
Primary rig is Green Thunder:
95' F-150 XLT 4x4, 302, 5 spd, MSD 6A, Flowmaster Exhaust, Sunroof, Clear corners w/ Diamond headlights, CD player with 2 10" subs and some 32" BFG Muds
.Thats it for now, saving for a stang. Check out my Gallery for a look-see.
Justin - One Happy FTE Member
Lead Driver
Joined: Sep 2002
Posts: 9,476
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From: North Texas
oxygen sensor wires cut. no code. affecting engine?
You gotta have that O2, mine wasn't placed centered after my Y-pipe went on and my idle was like crap. If it is unplugged, you should be throwing a code or two...
I replace them every 75-100K miles. Your gas milage is way low unless you drive with the foot to the floor all the time. You should have about 14-16MPG.
I replace them every 75-100K miles. Your gas milage is way low unless you drive with the foot to the floor all the time. You should have about 14-16MPG.
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Freshman User
Joined: Dec 2001
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From: Olathe USA
oxygen sensor wires cut. no code. affecting engine?
i know my milage is terrible. and i dont drive my truck like i stole it either. my truck will have a check engine light come on once about every 2 weeks, for about 10 min. or so. so i checked the codes, and it is 52 ; power steering. so i'm not getting a check engine light because of the oxygen sensor. but why not since it's cut? how do i hook this back up? there are no wires running to the sensor, just about an inch coming out of it.
Lead Driver
Joined: Sep 2002
Posts: 9,476
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From: North Texas
oxygen sensor wires cut. no code. affecting engine?
That is a start of why it runs liks ***. The computer doesn't know if it is running Rich or Lean.
I'd just buy a new Bosch sensor. They are like $50. Get some penetrant b/c that old O2 won't budge for anything without it.
Do you still have the factory harness hanging down (black plug)?
How many miles are on your truck? Maybe it also just needs a good tune up like: plugs, spark wires, air filter, PCV valve, oil breather filter, etc.
I'd just buy a new Bosch sensor. They are like $50. Get some penetrant b/c that old O2 won't budge for anything without it.
Do you still have the factory harness hanging down (black plug)?
How many miles are on your truck? Maybe it also just needs a good tune up like: plugs, spark wires, air filter, PCV valve, oil breather filter, etc.
Thread Starter
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Freshman User
Joined: Dec 2001
Posts: 48
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From: Olathe USA
oxygen sensor wires cut. no code. affecting engine?
first of all,my truck doesnt run like ***. everything is in tip top shape, and it runs fine. the idle is a little high - 850 to 1000 instead of 750. is this a symptom of a rich mixture? i have no wires, harness or anything else hanging down to the sensor. where do i look for this? where does it come from/run to? thanks.
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Lead Driver
Joined: Sep 2002
Posts: 9,476
Likes: 2,009
From: North Texas
oxygen sensor wires cut. no code. affecting engine?
Oh sorry about that, I thought it was running crappy.
There should be a black plug from the factory engine wiring harness hanging there somewhere. If not something is wrong. You may need to hit a junk/slavage yard for the factory plug if yours is gone and search for those wires and splice that plug in.
I used to have a badass TownCar that ran mid 8's in the 1/8 and I disconnected the O2's once and got like 4MPG out of it! Needless to say missing that O2 is bad. I did that b/c I figured they were bad but it turned out that I had too much fuel at idle with low vac from the cam.
I presume you didn't cut that plug off so...maybe some one made the computer to run in an open-loop (I think that is what it is called)where the O2 is stoich. But I doubt that.
There should be a black plug from the factory engine wiring harness hanging there somewhere. If not something is wrong. You may need to hit a junk/slavage yard for the factory plug if yours is gone and search for those wires and splice that plug in.
I used to have a badass TownCar that ran mid 8's in the 1/8 and I disconnected the O2's once and got like 4MPG out of it! Needless to say missing that O2 is bad. I did that b/c I figured they were bad but it turned out that I had too much fuel at idle with low vac from the cam.
I presume you didn't cut that plug off so...maybe some one made the computer to run in an open-loop (I think that is what it is called)where the O2 is stoich. But I doubt that.
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