View Full Version : question about 02 sensors and scanners

04-05-2010, 08:36 PM
So I am checking my car over. and trying to track down the strange idle it has from the time it goes into closed loop.

everything is normal looking on the dcl feed of the scanner.

TPS .9v
coolant temp 199 and changes with fan
but o2 sensor. is .07 and never changes......

the scanner doesnt give me the option to look at each bank individualy.

can some one enlighten me on the .07 and never moving thing.

i am assuming that the sensor is dead but which ones. both or just one.

sorry for the NOOB question i dont know ford systems 100 percent and expecially ones back in the day. I know german systems but it seems ford did things a bit differently back then.

oh yeah.... I have no vacuum leaks.....!!!!!!!

04-05-2010, 11:21 PM
all I know is that the voltage should be switching if sensor is functioning properly

04-06-2010, 05:52 AM
if its not telling you which o2 then im not sure how you can track which 1 it is. however the o2's should be all over the map. acting like crack heads at a free crack give-away. check you wires first, if all good then hit autozone for some new sensors and get 2 nuts aswell. most likely your going to need them. i think i got mine for around $35 each. and the nuts for around $8

04-06-2010, 12:32 PM
YES, I understand that the sensors should be swinging from 250mV to 750mV back and forth.

but I am wondering if there is another problem with this car that is forcing the exhaust to be rich. like a air flow meter. or something.. I know german cars will default the o2 sensor readings (older cars) to a preset value if there is a problem and never change but they have check engine lamps usaully.. I have no check engine lamp on.

i think I have more of a problem with my scanner (auto x-ray) than anything. we tried it on a ford truck of the same years and it gave same problems. KOEO and KOER tests it just says the car is not responding. but I can read the data stream so i know it is talking to the car.

it asked for year and vin and i entered 1992 and vin r. are there any other tricks to get them to read?

also I have numerous faults, when I do the jumper test it flashes all sorts of codes at me but i was getting kicked out of shop for night so didnt get to write them down.

04-06-2010, 01:55 PM
Either the O2 sensor is shot or you are running lean which will create a host of other issues.


04-06-2010, 02:04 PM
But wouldnt .07 or 700mV be a rich condition?

i ordered a new scanner so I can watch them better and acutally watch the other sensors ..

my injector PW was any where from 1.8ms to 2.2ms at idle. does that help?

04-06-2010, 02:16 PM
.07 is 70mV, 700mV is 0.7 volts. .7V is rich, .07V is lean.

I'm assuming your car is a SC, so I'd recommend dropping the scanner and going with a QH which is alot more versatile and datalogs alot more at near real time.


04-06-2010, 02:30 PM
yes, its a 1992 SC. gotcha on the mv thing.. it does run like its lean to me.

but they still should move when fuel is added to the intake. (i know its not safe but it works) I used some starting fluid and changed the mixture a bit and no change.

hmm the car runs perfect till it goes into closed loop.

can I ask what a "QH" is...

thanks for the help

04-06-2010, 03:25 PM
can I ask what a "QH" is...

Moates Quarterhorse. http://www.moates.net/product_info.php?cPath=31&products_id=199

A chip you can plug into your engine computer to run different tuning parameters and datalog most of what goes on inside the engine computer.

It is literally the most bang you can get for your dollars in data logging the EEC-IV computer.

04-06-2010, 03:35 PM
yes, its a 1992 SC. gotcha on the mv thing.. it does run like its lean to me.

but they still should move when fuel is added to the intake. (i know its not safe but it works) I used some starting fluid and changed the mixture a bit and no change.

hmm the car runs perfect till it goes into closed loop.

can I ask what a "QH" is...

thanks for the help

When the car is first started, does the O2 sensor read high volt as in rich, then it goes to low volt... or does it always set at the low voltage.

If it stays at low volt, then I'd say its shot and its time for a new one.


04-06-2010, 05:29 PM
always was showing 0.07V no matter what I did. hot or warm, vacuum leak, rich forced condition it never changed.

but the other question is the scanner just says o2 sensor, it doesnt break it down to which bank.

04-09-2010, 11:41 PM
so after a week of waiting I got the snap on modis and played around with my running issue.

KOEO test showed no faults.

KOER test are what followed..

I have faults for both o2 sensors not switching.

but I can figure out what code 10 is...???? SNAP THROTTLE???

also I included the data stream all values for you to pick over.

the bank 1 o2 senosr never changes and the bank 2 barely changes.

let me know if anything sticks out to you guys.


04-10-2010, 11:03 AM
anyone have input on this???

04-10-2010, 11:50 AM
Sounds like your O2 sensors are either not connected properly or not working properly. I can't remember if reading "lean" means grounded, or open.

10 is a code for all is well. I assume Snap throttle is snap-on's version of the Goose Throttle command. Basically you are supposed to rapidly push the throttle to WOT, and release. This allows the KOER test to check TPS range, and MAF changes. During that test you should also be commanded to turn the steering wheel 1/2 way around one direction, as well as step on the brake once.

If you fail cylinder balance test, it should tell you what cylinders fail. If not, perhaps you're failing the KOER test due, not cylinder balance.

04-10-2010, 11:55 AM
well the o2 sensors are kinda a no brainer they are hooked up properly to the correct connectors.

I am leaning towares them being done and need replaced. but just wana be sure.

i did the test as per snap on machine, steering wheel turned, brake pressed, and snaped the throttle.

all the faults I get are for the o2 sensors..

I will smoke check the vehicle today to verify 100 percent there is no leaks and change the o2 sensors.

If I dont find a leak I will have to suspect that there is a cyl or two not doing anything (injecting fuel) and just acting like an air pump. but wouldnt the cyl balance test show that...??

04-10-2010, 08:31 PM
Well smoke checked the complete engine for leaks, and i have two.

the large leak is at the dipstick tube the dipstick no longer has the oring in it so its leaking like mad...

plugged up dipstick and the second leak became clear.

the bypass valve behind supercharger is leaking on the piviot just like an old carb. I dont think there is any cure for this other than replacing the valve thing. is this true??

so other than that there is no leaks no pin holes in lines. nothing.

so i guess the o2 sensors get changed next.

04-11-2010, 12:58 AM
for those who have not played around with a smoke machine, here is a pic of the leak on my bypass valve.

if you look at the shaft that holds the butterfly in the valve you can see misty smoke around there. the pic doesnt do it justice.

the smoke is very strong citrus smelling and is very easy to see with just a flash light.