Heated lambda sensors

[Rodd1s]

Got a problem...

MY car failed its emissions test due to the O2 sensor showing minimal or no activity because it's not heating up to optimal temperature where I've set it so far back when i put on the 4-2-1 exhaust manifold.

What I'd like to know is, can anyone guide me as to how i can go about using a heated o2 sensor when there is only the single wire connection for it, ie: to enable the pre-heating, could i just run a switch or relay straight off the battery or ignition live?

The CEL is also lit, showing code P0134 (o2 sensor circuit no activity, bank 1, sensor 1) and lambda readings at idle was around 0.8 to 0.9, altho at higher engine speeds it seemed to hover around 0.950 to 1.020.

Any help appreciated guys, if i dont get this sorted in the next week the car will be seeing the scrap yard and dont really want to put it back to standard just for the sake of keeping the car on the road i mean, whats the fun in that? and it'll cost a lot for nothing really lol

[benzino]

just a thought, but is mounting the sensor higher an option?

or what about putting the old manifold back on and modifying the pipe to allow a quick swap (i.e. flanges and pipe to make up for the pipe on the 4-2-1) just for emissions (kind of like doing it with a de-cat i guess).

you could put a relay on ign1 and see if the heated sensor helps (maybe you could get one off the scrappy just to test) but i'm unsure whether it would need to be heated all the time (and then a switch would help maybe even temp controlled for when it reaches running temp.)

good luck

(you would rather see it go to the scrap rather than put it back to standard? that's a tad dramatic)

[Rodd1s]

putting the old manifold on is not an option, because i dont have it or the front pipe or close-coupled cat.
and there's no 'quick swap' option when it comes to exhaust manifolds lol.

as for the heated o2 sensor, ive got a 4-wire one, and it will need to be constantly heated because of how far back from the head it sits.
and it could be relocated (like the later 4-2-1 manifolds made) but then it disrupts the flow on once cylinder, where ive put the sensor as soon as it all comes into a single pipe (almost 3 feet back from the head)

i just need to know where i need to run a relay to/from and what fuses i'd need to use because i havnt a clue what power the heated o2 sensors need.

[benzino]

relay would be wired: battery (+) and ground with ignition 1 as the switch

so that way it would turn on as soon as the ignition is turned on.

as for required power, do you know anyone with a heated sensor? maybe you could measure theirs

[Rodd1s]

relay would be wired: battery (+) and ground with ignition 1 as the switch

so that way it would turn on as soon as the ignition is turned on.s

Really? I couldn't have guessed that myself.

as for required power, do you know anyone with a heated sensor? maybe you could measure theirs

The lanos already has a heated O2 sensor, but its a different make, they all are... it means i have to go find a car with the exact denso sensor im using and then prod some wires round the back of it?

No offence, but this really isnt helping. all i need is a base value for what kinda power a heated o2 sensor's heater may run on, cos ive worked out that it will need to be constantly heated as the exhaust cools too quickly even after hard driving.

[benzino]

cool your jets dude...

i just need to know where i need to run a relay to/from and what fuses i'd need to use because i havnt a clue what power the heated o2 sensors need.

relay would be wired: battery (+) and ground with ignition 1 as the switch

you ask a simple question you get a simple answer...

also, if the lanos' in the UK

already has a heated O2 sensor

, why don't you just use the one you already have, with the wiring that's already there?

If you want specifics post up more details...



http://www.aa1car.com/library/o2sensor.htm
take note "Replacement O2 sensors must have the same number of wires as the original, and have the same internal resistance."

also wiring diagrams I have seen for heated o2 sensors (thanks google), the sensor was given 12V but that was regulated by the ECM (it did not give voltage parameters though)

this discussion ( http://www.kia-forums.com/2g-1998-2001- ... lease.html ) seems to say that the heater just needs constant +12v


now it's your turn to search

[MMamdouh]

i never saw a lanos with a heated O2 sensor

MMamdouh

[benzino]

yeah, neither... maybe it's cause we live in hot climates Mohamed

[Rodd1s]

i never saw a lanos with a heated O2 sensor

MMamdouh

Later-model lanos's had a second 'downstream' heated o2 sensor. but i cant use that as the primary because it is already needed for monitoring the cat-converter.

[RichieOzzie]

I have been looking into this as well.

Now this is how I have it figured. Having found out what is suitable to replace the standard one with, and then consider the screw-thread it has.

Next would be a good idea to heat it permanently, as most cars seem to have this, and it doesn't doo much in the way of damage. I would fabricate a timer for about 2-3 seconds to swithch the heater element on, and then leave it latched until the engine is swithched off. The reason is the power they consume at connection is quite high, and I wouldn't like to load-up the electrical system at startup time, only once it runs, which is generally what other manufacturers do.

I think a 4 wire O2 sensor is the best bet given the connection to ground should be good for the sensor element.

The constraint is the resistance of this part, and the screw thread. They all work on the 0-0.9 volt range, its just the resistance of the element for the ECU would be important to get a good working set-up.

I have built timers from kits you buy at electronic stores to do things like this, and if you connect it to switch a 20-30 amp contact relay on, this should be sufficient to apply power to the heater circuit.


+ 12v ---------{ign power on} ----|Timer|-------{relay}------- ground

When relay closes, it will apply power to the heater to ground of the heater.

Relay std Bosch type one for 30Amps.

YOU MUST use a fused connection to the battery at the battery connection +ve.

The Alternator feeds to the fuse box to a fuse, then to the battery to charge it. This would be the T-off I would use to apply power to the timer. MUST be Fused to about 3amp for the circuit.

It would be good practice to fuse the relay N/O contact to heater connection to 30Amp also to avoid damage to the contacts should a fault occur in the O2 sensor heater circuit.

Good timer setting would be 2-3 seconds before it activates.

The tri-angular lines are Earth points in the circuit.

There will be a wire somewhere in the car that becomes live after the engine starts, maybe the alternator is a good one to use, as this will only activate the timer & the Relay once it is turning, and therefore the engine is running. If not, and you use a normal power connector, like when the "Reds" are on for a while, it could slowly flatten the battery..... which we dont want!

Kind of like this the circuit would be. Excuse the drawing, I can't use Paint too well!!

[Rodd1s]

I managed to fix it... temporarily, it seems.

Used a Denso 4-wire O2 sensor that came off a Toyota of sorts...

Found a 10 volt IGN live wire near the brake servo... ran the relay off that. Seemed to work long enough to get it thru emissions test, now i've got P0134 again after a week's driving.

My car don't like O2 sensors

Gonna have to check everything over at the weekend to see if anything's broken/missing or otherwise inadvertently demolished.



So... its passed emissions, then only to fail the MoT test on a "f*cked" nearside wishbone ball/flex joint. Great!