Too lean on one bank

[Chappo_1]

Hi all, I checked my spark plugs yesterday, and found that all three on the right bank were very white, way too lean a mixture it looks like. The ones on the left hand side looked fine, a brown colour.

A few years back, I had the car at a Holden dealer to have it checked out for a problem with it idling too fast, and the auto shifting hard. It would not play up while they had it, but they did find an unrelated problem. I was told the only error they could find was with the right hand oxygen sensor. I was told it was a ‘bit lazy’.

I hadn’t noticed any problem until now. What I would like is other opinions on this. Does it sound like I need to replace the oxygen sensor? Or could it be something else?
I think new would be best for a part like this. Or are they usually reliable, would one from a wrecker be OK?
I think having too lean a mixture would cause it to be getting too hot at combustion. I think this could hole a piston crown???

Any advice would be much appreciated.
Thanks, Chappo.

 

[Immortality]

whats the fuel consumption like? was it the drivers side bank that was showing lean? possibly a vacuum line that has come off under the TB. this is a common problem. check for fault codes and see what that shows. if nothing else fixes the the problem then you can try cutting the wire for the heater in the O2 sensor, drivers side. if that doesn't work then possibly try a new sensor. don't get a used one. there is a wiring design fualt with the O2 sensors on the VS that effects the drivers side sensor. cuttingth epink wire is a quick fix. also try cleaning the 2 earth points under the DFI module where the sensors are earthed

 

[Chappo_1]

Thanks Immortality. It is on the driver’s side I have the problem. I have not noticed any change with fuel consumption.
I will check for error codes tonight, and look for any vacuum lines that have come off. I’ll report back what I find.
Very interesting about it being a wiring design fault. What is the drawback, if any, with the quick fix of cutting the pink wire?

Thanks for the help.

 

[Surfwagon]

The O2 problem is discussed in the following thread:
http://forums.justcommodores.com.au...97/91979-really-bad-fuel-economy-problem.html

SW

 

[Chappo_1]

I have checked for error codes and got two error codes:
Code 76 - Air/Fuel ratio variation between left and right banks
(which I already knew )

Code 97 - Canister Purge Solenoid and/or Circuit
The only canister I know of is the one near the driver’s side headlight that has something to do with collecting engine fumes for sending back to the fuel tank. I don’t expect this would be causing the lean running on the driver’s side cylinders.

I cannot see any earth points under the DFI module, which from what I have read is the plate that the coils are mounted on. Please correct me if I am looking in the wrong place here.

I have two brown wires, a white, and a purple wire going to the O2 sensor, I assume the pink wire mentioned would be the purple one I can see. Not sure if I should cut this, or try a new sensor. If it is a wiring fault causing this, then if I buy a new one, the fault will still be there.

Do you think I should cut the purple/pink wire and see what happens?
Should I worry about the code 97?

Thanks heaps, Chappo.

 

[delcowizzid]

purple will be signal to ecu browns will be heater power and earth white 02 signal earth if fixing the earths or cutting the heater wire doesnt help ide say the sensor is getting stuffed on the side that is richer plugs should be very clean and white

 

[Chappo_1]

Thanks for the help guys. I'll get two new sensors I reckon. I won't bother cutting any wires, at this stage.

 

[Immortality]

the pink wire is in the main loom so you will need to see what it turns into for the O2 sensor wiring (i think it's one ofthe black wires). i'd suggest cutting the wire first and see what happens. others have tried now O2 sensors that have worked for a short time but then also fail.

don't worry about code 97 for now

 

[VS_Pete]

I cannot see any earth points under the DFI module,
Thanks heaps, Chappo.

Mate that is for a vr.

Here is pics for vs.
Should explain everything.

There on two studs one is located at the front of the engine block that clearly visible its located just south of the water out/in? larger hose joint for the heater and the other is located near the loom for the passenger side O2 sensor its the bolt on the back of that head... make sure to clean both the connector and the mating surface thoroughly and also the wire thats clamped to the connector..

 

[Not_An_Abba_Fan]

They are not O2 sensor earths, the sensors earth back to the ECU on the VS, they are just common earths. The sensor earths may pick up on them but they go all the way back to the ECU.

Also, it is probably mentioned in the thread SW linked to, but the O2 problem is not an earth problem. It is a heater problem. You get some voltage leak from the heater wire to the signal wire and this will affect the voltage that the ECU picks up from the RH sensor. I don't know why it only happens on the RH one, but it is a known fault by Holden and cutting the pink heater wire on the loom side of the RH sensor plug fixes it.