O2 sensor question

White Lincoln

White Lincoln

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1994 Mercury Cougar XR7, 3.8L, all stock
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As you may have read several months ago, I had codes 137 / 173 which basically where saying the O2's are out of range and running too rich for the PCM to compensate. Last week I replaced my O2's with a pair I bought last year. I ran diags today and the 137 error is gone, but the right bank o2 is still showing 173 "running rich". Since I have my car running pretty well now, the O2 may be the issue since the left back error went away with an O2 swap. My thought might be that after the last several years of running my engine with my timing off may have damaged the O2's.

I read an article on "cleaning" the O2 using a propane torch. Anyone done this before and the cleaning showed enough positive change to not buy a new set?

The O2's I had in before last week were BOSCH 15716.
The O2's I replaced the one's above with are Bosch 15717.

The diff from what I read is the length of the connector cable. 15716 has short connectors and 15717 has long connectors. Otherwise, they both are rated for my 94 3.8l.

Amazon has the Bosch -16 O2 for $19 and says it is a downstream (which does not matter on my car) and an exact fit.
The - 17 O2 is $29 and just says "Compatible with Select 1989-16 Ford, Jaguar, Lincoln, Mazda, Mercury"

RockAuto has the MOTORCRAFT DY1401 for $45. I'd buy that if I knew I was not wasting money and the Bosch for $19 would probably do.

Thoughts? Comments?
 
I just noticed something.

The 94-95 Mustang 3.8l uses 4 sensors, two upstream and 2 downstream.

The upstream is a BOSCH 15719 and the downstream is the BOSCH 15716, the one recommended for the 94 3.8l Cougar.
*Ignore this... the 15719 is for upstream for a V8, not a V6. Geez... these parts sights can really mislead you.

Should I be using an upstream sensor instead of a downstream (since we technically do not use a downstream O2)?

NAPA says do not clean, replace. But there are tone of articles on cleaning an oxygen sensor. I also found a lot of ways to test an oxygen sensor.

I think I will be testing the O2's to verify they are working or damaged. Seems an easy way is to (as mentioned) heat the sensor to see if it produces low voltage, set voltage no matter the heat, or nothing at all. 2nd two indicate it is bad.

Thanks for reading!
 
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If you have a fault code pending or confirmed on one bank only, your first step in my opinion should be to swap the sensors between banks and see if the fault code swaps sides, too. If yes, blame the sensor.

I posted about an O2 code a while back, though that was a downstream code. My car is a 97; not sure what year the downstream sensors were added.

My car had three NTK (or whatever that brand was) and one Bosch sensor, the latter being the problem. When monitoring the sensor readings real-time via my OBD2 app, the Bosch sensor always read odd. I'd recommend against the Bosch.

Here is my old thread. Not directly related to your code, but still good reading about O2s including plenty of advice from expert members:

P0156 is back

Ugh. Alright, some of you may remember that I had this code last spring. Bank 2, sensor 2, oxygen sensor rear/left. Back then, all I did was reposition the connector which kept hitting the underbody. The code never came back (till now), and I eliminated an annoying rattle in the process...
forum.birdcats.com forum.birdcats.com
 
Thank you 97. I heard the same about Bosch and these are not old enough to go bad like that. I bought a couple off brand and we'll see later this week if the code goes away when I replace the current o2s. If the new ones go bad, I am going motorctsft.
 
I've heard of cleaning with a propane torch, but I've never bothered trying. I usually just monitor O2 sensor voltage via a scanner and replace them it it is not reacting, but I don't think you have that ability with the OBD-I on your car. Given that, 1997ThunderbirdLXV6's advice of swapping them side to side and seeing if the code follows the O2 sensor isn't a bad idea. I've used Borscht sensors on these cars before without any issue. They also make really good dishwashers.
 
KevinVarnes said:
I've heard of cleaning with a propane torch, but I've never bothered trying. I usually just monitor O2 sensor voltage via a scanner and replace them it it is not reacting, but I don't think you have that ability with the OBD-I on your car. Given that, 1997ThunderbirdLXV6's advice of swapping them side to side and seeing if the code follows the O2 sensor isn't a bad idea. I've used Borscht sensors on these cars before without any issue. They also make really good dishwashers.
Click to expand...
Did you mis-spell the word Borscht? Cause I think your missing an i.... :p

I soaked them in gasoline overnight. What the heck, I can't dance so this was the next best thing.
 
FYI: I ran the voltage tests on the Borscht O2's and they did what they are supposed to. Hook up the grey and black wired posts (I think grey is +) to a VM Meter, turn it to millivolts (200 at first then as the voltage output increases, change to 2000) and heat the sensor with a propane torch. If the O2 is bad, it will have a constant voltage or no voltage, if it's good, it will climb up to around 800mv and stay there until heat is removed. You will notice, when the sensor is at 800mv, it is red hot.

Hope this helps someone else down the road.
 
Update: I received the O2 sensors last night and installed them. I drove the car around till the engine was at normal temp. Plugged in my Snap-On scanner with the Ford, GM, Chrysler up to 93 (my car was made 12/93) and the results where codes 137 /173 rich... frack.

A few things i am thinking are borked... 1) Scanner does not have the correct cartridge for my car. 2) Injectors, though correct per all documentation, run rich and are not for this car. 3) The O2's I bought are crap. 4) PCM has issues. I have a few ideas to test out, like drop by my friends house and put his scanner on my car.

Someday I will find out why this is happening and until then, just drive the car the way it is, which to me is pretty nice compared to the way it drove earlier this year.
 
all o2 sensors read the same, so if it reads at all,the scanner should read the right voltage. the rest who knows.
 
Grog6 said:
all o2 sensors read the same, so if it reads at all,the scanner should read the right voltage. the rest who knows.
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Funny, I was thinking pretty much the same thing. Since everything else has been replaced that could cause the rich fuel (better to have rich than lean), my guess its in the injectors or some other part that crapped out or is not made for my engine. Could be the PCM since I replaced that years ago due to other issues I was having. At this point, it is more research with my notes I have of what I have done and seeing what may have transpired from other issues and what may have caused the O2's to report a rich output. Thanks for everyone's input into this. It always helps to hear some feedback when faced with a stumper.
 
A parts store will rent you a test kit, that has lamps; makes it obvious.
 
Grog6 said:
A parts store will rent you a test kit, that has lamps; makes it obvious.
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Hey Grog, not sure what you mean "that has lamps, makes it obvious". You mean for detecting what might be causing the codes?
 
I thought you were referring to "The Noid" (nerd) until I looked it up. Harbor Freight has a Noid kit for $30. I never saw one in the list of Autozone check out tools.

noid.jpg

I have never used one, but in my case, being controlled by a PCM and not being able to manage the engine beyond that, AND not having much output from the PCM other the obscure codes, this might come in handy. Will do some research on what it can do and if its applicable to my issues. Thanks Terminator!
 
Autozone does have the Noid for rent.
 
A noid light will tell you if a signal is getting to the injector to tell it to fire, but it won't tell you what the injector is physically doing.
 
KevinVarnes said:
A noid light will tell you if a signal is getting to the injector to tell it to fire, but it won't tell you what the injector is physically doing.
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Correct. All it can tell you is if it is getting the pulses. It also won't tell if it is dumping too much gas in the cylinder. Just another small tool to weed out issues.
 
I came across an interesting article (see below) the other day on code 137. According to the article, a 137 is due to exhaust leaks or a bad O2. Since I ruled out the o2's being bad by using new ones, and the last code I got after changing the o2's with ones I knew were good, I think it is due to the exhaust leaks.

My last test before changing the o2's with new ones, I got ONLY the 137 error, the 173 error went away (rich o2). This would most likely say "take care of the crappy exhaust system and call us when you are done..." Just found this interesting.

ODB-1 code p0137 o2 sensor solved with fuel pump, but why?

1993 Ranger 4.0 with 170k or 270k miles. ODB1, so not much diagnostics. P0137, Oxygen sensor not switching/system rich Left or Front HO2S code throws everyday. So of course i did the wrong thing and replaced o2 sensor, still throws code. Replaced fuel filter, nothing. cleaned MAP and IAC ...
www.therangerstation.com www.therangerstation.com
 
SOB... after putting the original O2's back in the exhaust, the pair that read only one error, a P137 (which might mean exhaust leak), I tightened up the exhaust and it was loose, now the car runs like crap when cold and in gear.

Reading about possible issues with rough idle in gear seemed to mostly point to the IAC. I tested it by pulling the connection to the IAC and starting the engine (warm). The car starts and proceeds to run like crap. I suspect the IAC is fine. I have cleaned the IAC, TSP, throtthle body and whatever else might benefit from a cleaning. Friken weird crap. All I can think of is the cold weather hit about the time the car started running like crap when cold and putting it in gear. Meaning this is has been an ongoing issue but the weather was warm enough to stave off the engine acting up with cold weather.

Sigh... more testing.
 
theterminator93 said:
Refresh my memory - have we ruled out the MAF sensor?
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REFRESH, REFRESH, REFRESH....

The MAF. What can I say about the MAF other than one of the tests that is run during the OBD1 scan is the MAF and if it is reading the air flow correctly. I did replace it a few years ago but in the back of my mind I keep wondering if the cheap, RockAuto off brand was any good or has a short life.

I did happen to buy a new MAF senser and housing last year, plugged it in... nothing, zip, zilch, bitkis... nothing. No diff. Same codes. I sent it back. I know, I know.. that was just rotten of me to do.

So the next two steps I may need to take is, as mentioned, replace the exhaust and put something in place that is a correct fit or have someone weld what I have so it is correct and no reason for leaks after the CAT's. I keep thinking for the price of new exhaust parts, I could buy a cheapy Harbor Freight MIG and just learn to do this crap myself. One more skill for when I have to work after I retire. Oh geez, don't get me started.

I have yet to drive the car after the O2 sensor change and exhaust tightening and test the codes. I left the battery disconnected for a long time tonight to see if maybe, just maybe, it needs a reset.

God knows I could use a reset.

More exciting adventures to come from the Lil' Cougar that won't!
 
I tested the IAC and it moved in and returned back to closed without issue. I tested my other OEM one that is dirty inside and it did the same thing. On to the next test....

PS: I used my injector pulse tester on the IAC. Worked great!
 
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Follow up:
After pulling the IAC and letting the car sit without the battery for a long time, the car started and ran fine. No hesitation putting it in gear or acting like it would die.

I was going to run codes when I got back to the house, but its after 10 and Dereck is on tonight. He went to get a Chevy truck from his old land in Minnesota. How many trucks does that guy have? Baffles the mind.
 
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