Oxygen Sensor(s)

[MysteryTheatre]

I got an EFI light . and after testing the coolant temp sensor the MAS and the potentiometer, i mean i'm not sherlock holmes but its the oxygen sensor . because i unhooked both of them and it runs the samel. the other sensors are giving correct resistances when tested with an ohm meter. is there a known way to determine which o2 sensor is bad? i understand the test involves probing the ecu wire with a volt meter and finding if o2 sensor is putting out around .5 volts? also wondering if anyone knows if cleaning and replacing can work?
i found replacements at around 50 bucks a piece for a splice in . i'm certainly not above that, the one with the push-on connector is $200. ' 89 county 3.9

[atvsmurf]

since we are talking about lambda sensors(hehe, I just got a new manual and that is what those crazy Brits are calling the blooming things) what are the signs of a failing o2 sensor? other than the efi light?

[MysteryTheatre]

THE EFI LIGHT COMES ON AFTER a certain distance has been driven and it happens at exactly the same place down the road every time. i reset the ecu and unhooked the lamda sensors, and drove it and the efi light came on at the same exact spot as when they were hooked up. it has also come on at idle a few different times when the idle just got real rough. like most electrical parts failures heat seems to hasten the failure. i am assuming the sensors are not detecting the opened loop, so it reverts to closed loop. it also runs the same with the sensors unhooked. other than that the symptoms are only a strange idle after the efi light comes on, i believe because its in closed loop.
any ideas?
the other sensors are fine. so it must be the lambda
which by the way the english are not the only ones who call it that, my saab & volksie , had lambda's on the bosch constant injection system. both had analog
brains.

[OkieRover]

Originally Posted by atvsmurf

what are the signs of a failing o2 sensor? other than the efi light?

Decreased MPG. Like 2-4 mpg worse.

[Oscar]

You are using LOGIC when dealing with a LUCAS system........

Try swapping out the ECU with a known good one for a trial run.

[MysteryTheatre]

no ecu available.
what makes you think it is the ecu?
the car runs fine in"limp home mode" .
i believe there is a legit fault with a sensor.
i will test o2 sensors
.05-1 v somewhere in the middle if its running at stachiometric.

[trecker]

have ypu bought the sensors already? I think autopartswarehouse offer a good price for this. check this car parts

[MysteryTheatre]

pulled the sensors today, left bank looks good, fairly new japanese sagem sensor
very liitle residue , looked clean. Right Bank However was showing lots of white residue, signs of a lean mix, the sensor itself, is an Old lucas nkt , possibly an original. i cleaned them up for now but will replace the right bank, testing the voltage output it was low, signifying a Rich Mix ,and thus the ecu is fully leaning out the mix. even with the injectors opening for the shortest possible interval the ecu is still getting a "rich" sign from the failed sensor on the right bank. this is where my lean mis at idle on the right bank is coming from. and where the lean residue on the plugs and 02 sensor is coming from. i'll try your advise on the the part source thanks. i think i only need the one. by the way these are super easy to get at and replace.

[MysteryTheatre]

carpartswholesale.com 33 bucks and 2.95 shipping for the splice-in

[MysteryTheatre]

ok don't buy from carpartswholesale.com they list a part that supposedly fits range rovers , it doesn't it, has the wrong size threads , it is a tiawanese part.
their return process sucks! they refuse to pay for the return shipping even though it is their mis-information that is at fault. they don't speak any english or very little and are quite hasty , the overall experience is quite disconcerting.
I repeat : DONT BUY FROM CARPARTSWHOLESALE.COM , they are the worst hands down,
any way i got a line on a walker direct fit for 50 bucks free shipping. i am slowly learning to stay away from these huge internet parts places, especially with electrical parts.

[MysteryTheatre]

installed the new o2 sensor yesterday in the right bank, it runs good now.
used a walker direct fit i got for 50 bucks new, plugs right in. happy to have solved that problem and it runs smoother with better power and fuel economy now.

[SafariDave]

I need to replace mine in my 1991 RRC where did you buy it

[MysteryTheatre]

i got mine off ebay motors, there are a million listed, just stay away from the universal splice in deal from wholesalecarparts.com, it doesn't fit .wrong thread size. many parts stores sell the walker unit online but i think it retails for a hundred bucks. try discountbritishparts.com they sell a direct fit oem for 89bucks otherwise the options are (splice in) and there are many to choose from
as any other direct fit is about 150+

[ArmyRover]

global-automotive on ebay has the correct sensors about 60 bucks for the pair you do have to splice the connectors on though

[SafariDave]

Thanks guys!