jmca

Having the low load hesitation problem I went to have a look at the Lambda sensor last night - also in preperation for the DIY AFR.

• Thought the sensor was in the downpipe. From reading the posts & http://www.geocities.com/subman2001nz - this should be a 3 wire sensor.
• This sensor turned out to have a braided sheath over it & a cylindrical connection.
• The conenction to the sensor had two wires - black with a blue strip & red with a blue strip. When metered the black wire gave roughly 5V when ignition on.

Back to some posts I printed out, which led me to another sensor.

• Seems to be in the outlet manifold - same side of the engine bay except way way down - like under the engine - sticking out.
• Four socket connector.
• Red, black & white wires, which seems to go along with the bbs posts.
• Checked the voltage across red & black on connector side & got a 12V reading.
• Tried to get a 30 ohm reading on the sensor side as described in above site. NOTHING!

So figured I'd try the ECU end just to see. Located the wire (silver with white bands - in position sixth from the right - top row).

• Connected a DVM to the wire using the ECU fixing plate as ground (wasn't to sure about this!)
• Ran the car for a total of about 10 mins.
• It never gave any significant reading AT all. Didn't really matter if the car was running or not.
• Took the ground from the cigarette lighter - but still nothing!

What effect would this have?

Now I should have probably tried to take a reading in the engine bay by connecting a 12V supply to the sensor & take a reading from it's output wire to make sure but I take it my Lambda sensor has gone on a permanent holiday!

I do remember mention of a Hotwire & an NTK one. If anyone has any info on these & ease of fitting, could they please post. What about one from the local spare parts dealer.

Regards

Johny.


[Edited by jmca - 2/28/2002 10:59:34 AM]

[Edited by jmca - 2/28/2002 10:59:59 AM]

[Edited by jmca - 2/28/2002 11:00:25 AM]

[Edited by jmca - 2/28/2002 11:01:19 AM]

jmca

Very Very C O N F U S E D!

Just re-checked the readings there over lunch.

From the AFR thread I know to expect somewhere between 0V & 1V at the ECU. I am getting a constant 0.01V.

Checked the sensor side by applying a 12V supply to the heater wires & I get 5V from the output wire. Does the sensor act like a resistor lowering the applied 12V?

I really don't know HOW it gets from 5V output from the sensor to 0.01V going to the ECU.

Wondering if anyone knows the voltages relating to the Lambda Sensor itself & is there a change of voltages before it hits the ECU?

The cars a MY95 WRX (had work done on it before it left Japan) & surprisingly the ECU input wire has been previously joined with the wire directly underneath it - a grey wire with silver fleck.

I'd love to try & pinpoint what's wrong or to be changed as the current finances limit me a great deal & I'm hesitant to drive it much.

Johny.

Muncher

Try this thread I started when fitting my AFR meter, may help....

http://www.scoobynet.co.uk/bbs/threa...threadid=71258

jmca

Muncher,

Cheers for the help. I actualll had your post printed out & was using that as help.

I'm still unsure why the sensor gives 5V output when I apply power to it - yet only 0.01V on the input wire to the ECU. Gremlins?

Regards

Johny

Muncher

Hmmm,

The black and red wires on the socket (just under the water tank header) are for the heater on the Lambda sensor. The white wire is the sensor output that goes to the ECU. My faulty Lambda sensor was permanently on 0.3 volts.

A good link about how lambda sensors work

http://www.flash.net/~lorint/lorin/fuel/lambda.htm

In essence the 12v power is only for the heater. The sensor generates a voltage due to a chemical reaction with the oxygen. If you have applied a voltage to the sensor wire or accidentally grounded it then it's probably fried. Measuring the resistance of the sensor to ground is also unwise as current must flow through the sensor to be able to calculate the resistance.

I can't explain why your sensor input is 5V at the socket.

In your thread you mention the ECU wire being 6th in from the top right, silver with white bands, it is actaully 5th in from the top right, white with silver bands.

Giles

[Edited by Muncher - 2/28/2002 9:36:02 PM]

john banks

Apparently you can get replacement sensors from Halfords for £49 but I have not looked into it personally.

jmca

Mucher,

Sorry - actually meant 5th wire but 6th position on the connector block - the one highlighted in your thread. I had followed the guide for testing in my 1st post & tried to get 30 ohms but nothing.

I get 5V from the sensor wire itself - why - I don't know.

The wire I mention above - the sensor wire going to the ECU is soldered to the wire underneath (gery with silver fleck) & then continues into the loom. This is another I don't know why!

Does anyone know of an ECU wiring diagram for a MY95 as I may be able to find why these are joined?

I'm wondering what would the engine be performing like with a 0.01V input to the ECU? Rich? Lean?

John - Cheers for the info.

Regards

Johny

Background - The car has :

- Speed Meter sitting behind the steering wheel, which gives a digital speed readout, trip, timer, 400M stopwatch (activates when the car first moves. This is probably responsible for the speed restriction gone.)
- Greddy mech boost & elec Oil pressure guages.
- HKS turbo timer.

Not sure if any of these would affect the lambda wires though.