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View Full Version : Hypothetical bad O2 sensor.



huisjen
05-21-2008, 07:36 AM
Hypothetically speaking ;) if a car had a bad O2 sensor, and therefore had a check engine idiot light on, and therefore couldn't pass inspection without an $600 exhaust system rebuild, it seems like one could cut the sensor wires and insert a resistor that would mimic a properly functioning sensor. I wonder what the appropriate resistance value is.

Popeye
05-21-2008, 07:47 AM
might also screw up the fuel metering , for what it's worth replace the sensor and enjoy the improved driveability and fuel economy, it won't take long to realize 600 dollars worth of gas

huisjen
05-21-2008, 07:50 AM
In Maine, they just look for idiot lights on the dash. No dynamometer with an automotive anal probe here. If I tore open the hypothetical dash board and removed the LED, or cut the appropriate hypothetical wire... but I know where the leads are to the O2 sensor, and they're easy to get to.

Popeye, there has been no appreciable change in mileage due to the O2 probe coming loose (studs rusted off but the pipe is good) bouncing off the road a time or three, parking itself around the E-brake cable, then (when we couldn't re-thread the studs) getting welded back into place. The truck runs fine. I'm pretty sure that I'd do more environmental damage by forcing industry to manufacture me a new exhaust system than by driving moderately with the system as-is.

Mrleft8
05-21-2008, 07:52 AM
Why not just replace the o2 sensor? They can't cost $600...... Can they?

huisjen
05-21-2008, 07:59 AM
Doug, they cost about $120, but to install it I need a new pipe, which, by the time all is said and done, will probably mean the replacement of the whole exhaust system aft of the catalytic. The truck is 8 years/103k miles old, and will need that done eventually, but not yet. I can probably get another year or three out of the current system.

It works, as is, minus the idiot light. Why screw with it?

Popeye
05-21-2008, 08:07 AM
cut the wire to the idiot light

huisjen
05-21-2008, 08:15 AM
There are about a hundred wires that lead to the dash. I don't know which one it is.

Popeye
05-21-2008, 08:20 AM
put some duct tape over it

huisjen
05-21-2008, 08:25 AM
I'd have to disassemble the whole dash to tape over it, and then I'd use black electrical tape, but I don't want to dig in that far. It's a lot to take apart and put back together.

Popeye
05-21-2008, 08:32 AM
There are about a hundred wires that lead to the dash. I don't know which one it is.

the dealer/mechanic would know which wire to pull , they have done it before

paladin
05-21-2008, 08:40 AM
Dan....may take a bit....but what is the make and model of your vehicle and info specific information on the engine....

huisjen
05-21-2008, 08:49 AM
2000 Toyota Tacoma, Xtracab, 2wd, 2.4L 4 cyl DOHC EFI engine, 5 speed stick. I think it's a 2RZ-FE engine.

Paul Pless
05-21-2008, 09:12 AM
An oil change place may be able to reset your computer for a short period of time.

Paul Girouard
05-21-2008, 09:21 AM
It's all about the environment UNTIL it's about dollars out of a "enviromentist" own ass pocket , then it becomes a work around.:rolleyes: Maybe that word should be "hypocritical" bad O2 sensor? Maybe the Fed. should foot the bill , as you "mean" well? :confused: As it MUST really be about the carbon foot print and keeping it small , hence you "justification " about the whole job being "larger" IF the exhaust system gets replaced, YA sure thats a line of B/S if I ever heard one.

Pony up LT. or take it off the road!

huisjen
05-21-2008, 09:24 AM
Bite me.

Vince Brennan
05-21-2008, 09:33 AM
There are about a hundred wires that lead to the dash. I don't know which one it is.

Ahhhh... wiring diagramme?

Popeye
05-21-2008, 09:39 AM
not exactly the crime of the century paul , when others in here are personally trying to defrost the north pole

BrianW
05-21-2008, 10:01 AM
not exactly the crime of the century paul , when others in here are personally trying to defrost the north pole

It will be soon.

Environmentalist are already getting ready to use the Polar Bear listing, and it's case of sea ice loss due to global warming, to sue just about every industry they don't like.

The extra molecules of carbon emitted due to that faulty O2 sensor are killing the polar bears.

BrianW
05-21-2008, 11:17 AM
I know this was brought up recently, but maybe Dan missed it...

A link to a Toyota rust problem with 1995-2000 trucks

http://jalopnik.com/376911/rusty-toyota-tacoma-toyota-may-buy-back-your-truck-for-150-the-value

Tylerdurden
05-21-2008, 11:18 AM
Just weld the tabs of the sensor onto the pipe. I don't know how you diagnosed it but you should scan it then put a meter across the sensor to check output. If its a two wire and its hanging you lost your ground.

Tylerdurden
05-21-2008, 11:19 AM
I forgot about the recall, you might get a new truck out of the deal.
Start peeing on your frame:D

Popeye
05-21-2008, 11:29 AM
Just weld the tabs of the sensor onto the pipe.

if the pipe is rusty it won't take any weld , it will just burn up


I don't know how you diagnosed it but you should scan it then put a meter across the sensor to check output.which won't show anything


If its a two wire and its hanging you lost your ground. the pipe is gnd

Tylerdurden
05-21-2008, 11:37 AM
if the pipe is rusty it won't take any weld , it will just burn up

which won't show anything

the pipe is gnd


So let me get this straight, if you cannot figure out how to get to bare metal or there is none you saying you cannot weld it? I agree.

Testing the sensor will not show anything? Is it a psychic sensor?
How does it talk to the ECM?

Popeye
05-21-2008, 11:42 AM
might tack it if you are skillful , solder will melt , a rivet might do it but will just rust away eventually , a s/s sheet metal screw maybe , a clamp maybe , brazing maybe , but water and heat will probably just explode it , an arc weld will burn it up pretty good , on an old exhaust you typically loose gnd back at the studs coming off the manifold anyhoo

the sensor is not psychic , nor does it have anything to say

Tylerdurden
05-21-2008, 11:49 AM
might tack it if you are skillful , solder will melt , a rivet might do it but will just rust away eventually , a s/s sheet metal screw maybe , a clamp maybe , brazing maybe , but water and heat will probably just explode it , an arc weld will burn it up pretty good , on an old exhaust you typically loose gnd back at the studs coming off the manifold anyhoo

the sensor is not psychic , nor does it have anything to say

Ok so if I put a meter across a sensor that voltage I see is just residual effects from last weeks solar storm?

If you get a chance come down next week , I will have a whole bag of hairs to split.

Popeye
05-21-2008, 12:00 PM
Ok so if I put a meter across a sensor that voltage I see is just residual effects from last weeks solar storm?

well ... assuming it is a voltage type , you have provided a more plausible explanation than why someone with a dmm would be trying to check a dad burned unit that failed 50,000 miles ago ... yes

Cuyahoga Chuck
05-21-2008, 12:03 PM
I had a '91 S-10 with a a bad oxy sensor. The truck was very unpleasant to drive. It would start and run well till it started to warm up. Then the computer would get bad info and the fuel metering would go to hell. My motor was a 4.3 V6 with throttle-body FI. Don't know if a comparison is reasonable but if your truck has not had a decrease in performance and fuel mileage it doesn't sound like an oxygen sensor.
Has anyone extracted the fault code to guarantee that the sensor is bad?
To those that can fake out an automotive computer with a blob of play-dough or a wad of solder, you are wasting your time mingling with us plebians.

huisjen
05-21-2008, 01:40 PM
Okay, one more time, with feeling.

Roughly a year ago, while going down the road, I heard somthing go pop, then the sound of a major exhaust leak. Upon investigation I found the O2 sensor wrapped around the emergency brake cable by it's wires. It had bounced off the road once or twice, but seemed okay. There was no evidence that the computer had a problem with it, so when my mechanic told me he couldn't thread the rusted studs, which the nuts had rusted right off of, we decided to just weld it solid. We never did test the sensor, since I wasn't getting any indication it was bad. It was that, or rebuild the exhaust system, which looked like it had a few more years in so long as nobody screwed with it. A day later, the light came on. Okay, it could be something else, but the timing is awfuly suspicious. I took it back to the mechanic and asked what we could do about it. He told me that I was probably making extremely miniscule amounts more NOx, but otherwise it was fine and not worth fixing until I have to. It probably is worth getting the error code read just to be sure though.

As I said though, there's been no change in performance.

Yes, I know about the frame rust recall. I'd rather not trade this in if I don't have to and I see little evidence of frame rust. The '08 Tacoma is a larger truck with worse mileage. I'd rather keep this one, which is barely broken in.

Chuck, I suspect that Toyota may design these things so that when the sensor goes bad, it reverts to some default which keeps things running smoothly. Chevys default to running like crap.

Tylerdurden
05-21-2008, 01:46 PM
Chances are if its in limp mode when the battery goes dead for a while you may have issues. I don't see why you don't let toyota give you 1.5 times blue book. Find a good used 01.

abbyj
05-21-2008, 02:15 PM
It's all about the environment UNTIL it's about dollars out of a "enviromentist" own ass pocket , then it becomes a work around.:rolleyes: Maybe that word should be "hypocritical" bad O2 sensor? Maybe the Fed. should foot the bill , as you "mean" well? :confused: As it MUST really be about the carbon foot print and keeping it small , hence you "justification " about the whole job being "larger" IF the exhaust system gets replaced, YA sure thats a line of B/S if I ever heard one.

Pony up LT. or take it off the road!


This deserves a bump!

katey
05-21-2008, 02:51 PM
Hate to say it, but I like Tylerdurden's idea: let them give you a bucket of money, and find you an '01 with low miles.

Maybe they'd let you keep the engine as a spare?

Paul Girouard
05-21-2008, 08:13 PM
not exactly the crime of the century paul , when others in here are personally trying to defrost the north pole



Your right,,,,,,,, BUT it does show the hypocrisy of those "in the movement" ! It's pretty typical to see old "clunker" rigs around these parts to be burning oil so bad the back of the rig is black with soot , oil , etc , so much so the "Save the whales" , "Black top is forever" , "Hug a tree , shoot a logger" ,bumper stickers are barely legible. :rolleyes:

So it goes to intent and/ or credibility.

Paul Girouard
05-21-2008, 08:17 PM
Bite me.



Nah I don't need to , you took a big ole chunk out of your own asre better than I ever could :D

Your Environmental credibility / carbon credits rating is exactly .0000000000, all your own doing.

Nice job!

Popeye
05-22-2008, 07:15 AM
paul , dude is stretching it on a four cylinder 8 year old small pick up truck with a manual transmission , he is willing to switch off the engine and coast while driving to save a little fuel

leaving the oxy sensor in disrepair is hardly a crisis management situation , properly functioning it leans out the fuel mixture ever so slightly for marginal performance gains

considering how everyday items like correct tire inflation and planned trips saves way more gas , i think we could cut dan some slack

Gary E
05-22-2008, 08:10 AM
Well... you did claim to SAVE $$$ and save the inviroment when you drive a JAP car... How much are you saving now ??
SO...PAY UP... or sell the JAP CRAP to some other idiot.

How do you KNOW that it's THAT sensor?
and not another one??

Paul Girouard
05-22-2008, 08:44 AM
i think we could cut dan some slack



I think you should use some capital letters , at least ONCE in awhile :D

This is the bilge , slackers rule it!

I go by a old USN motto , " There is NO slack in light attack!", so nah , no slack for the LT. from NAS Whidbey Island home of the Intruder and Prowler.

Have a nice day!

Popeye
05-22-2008, 09:12 AM
Every car with a manual transmission is a hybrid

all one need do is , shut the engine off , put it in first gear , clutch out... now turn the key and away she goes

brad9798
05-22-2008, 05:16 PM
In Missouri, they plug in the car (the computer, anyway, to the monitor), so cutting the line to the light makes the instrument panel look better ... but it won't pass mustard.