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[swordfish]

Hi,,
the omega has 3.0 cats and down pipes but its a 3,2 . so i need to fit the extra lamba sensors to each bank of down pipes . looking at the position of the lambas i can see its the front sensors that need fitting . which means i will need to remove the down pipe first to fit . so my question is does it matter were the sensors go due to the fact that there is no front cat ... 
Thankyou

[TheBoy]

no, you need to fit the rear lamdas, after the main cat.

[swordfish]

ok thankyou ,,
do you know how to identify which plugs are front and rear   

[Doctor Gollum]

The two sensors not currently fitted need to be plumbed in after the main cats... Wire length will determine left and right.

There is a guide.

[swordfish]

ok thankyou , the plugs have been moved from original location , so not sure were they belong . were is the guide
please 

[BazaJT]

Can't do links,but go to maintenance guides then maintenance guides index and scroll down to V6 engine bit and there's a guide there.It does however state to fit front sensors between pre-cat and main cat.You no longer have pre-cat and DG and TB seem to be saying fit after main cat,so I'd clarify that bit prior to fitting.

[Doctor Gollum]

To be clear, it's a pretty standard 3.2 mod...

Front sensors are close to the manifold so get the shit kicked out of them resulting in an almost permanent pre cat code.

Rear sensors are between the Cats ie before the main cats. This is where the sensors are on the 3.0 exhaust.

The front sensors simply need fitting after the main cat.

Without seeing the car, it is impossible to say what's what. Wire colours to each sensor and their physical location might help, but requires detailed specifics rather than "the plugs have been moved"

If James fitted the Cats, he may be able to shed some light, but he has obviously been well off his game lately.

[BazaJT]

There you go clarification indeed,even I can follow DGs description

[TheBoy]

To be clear, it's a pretty standard 3.2 mod...

Front sensors are close to the manifold so get the shit kicked out of them resulting in an almost permanent pre cat code.

Rear sensors are between the Cats ie before the main cats. This is where the sensors are on the 3.0 exhaust.

The front sensors simply need fitting after the main cat.

Without seeing the car, it is impossible to say what's what. Wire colours to each sensor and their physical location might help, but requires detailed specifics rather than "the plugs have been moved"

If James fitted the Cats, he may be able to shed some light, but he has obviously been well off his game lately.

That reads incorrectly.

As the Front sensors go in the existing lamda holes in a 3.0l downpipe, and the rear sensors need fitting into a new hole after the cat.


On a 3.2, the issue is the pre-cat (Starting Cat in GM terminology) is really shite, as done after the penny pinchers took over and produced the DBW V6 models.  The main cat on a 3.2 is shite as well, but "good enough" to keep the ECU happy.

[Doctor Gollum]

OK, stand corrected, but it is still impossible to know how this car was set up without seeing it/accurate information from the person that fitted the 3.0 cats.

And for someone who trades in Omegas, Mr Fish needs alot of support.

[biggriffin]

The lands wires and connectors are long enough, you need to un-clip them and re-route using cable ties, when fitting the lamda's the first lamda goes in the new hole,which is put after the cat on the 3.0L down pipe.

Did mine years ago, never any problems at not time,with emissions.

[swordfish]

ok thankyou,,
do you know if the front and rear lamba sensors are the same

[Doctor Gollum]

Pay for my travel and time and I will tell you...

[cam.in.head]

Hi.ive just been out and put mine up on the ramps for you to see if I can help.mines a 2.6 but same idea as 3.2.and has the standard 4 cat system fitted.
All 4 lambda sensors are the same in theory but the standard front ones do seem to have a longer cable than the rear ones thou not by much.ive had a look at each connector hoping that they would have a different colour wire coming to the different ones and they appear the same.looks like pink,green,brown blue but not sure if they have faded or wether they have an additional trace colour on each. Not obvious from what I can .so no help there I’m afraid.all I can say for sure is that the cables come from a loom and end up on brackets near the rear of the gearbox.split to each side.upper connectors fold back and go to the front(first)sensors on the section of pipe from the manifold(before cat) and the lower connector goes to the rear(second) lambda sensor.on mine it is after the main cat and these are the ones which are missing on yours.you would assume or hope that your front sensors are connected to the front sensor sockets and are the right way round(lh vs rh)or it would run realy bad but this could be confirmed with a code reader that does live data if needed. It sounds like you just need to buy two lambda bosses to weld into your exhausts just after the cats and a pair of sensors.(wether you buy new pattern or new bosch or fit two s/h  bosch used to match what you presumably have already is up to you) ! 
As been mentioned earlier the front sensors control the engine fuelling and go before any cats.and the second sensors only fitted to later cars just to monitor cat performance and do not affect running but will bring up elm if not fitted on yours or if a failing pre cat on standard system.

[Doctor Gollum]

Sensor cables are different lengths according to gearbox fitted.

As the car/wiring has been modified, the only way to be clear what's what is to either see it or have the person who carried out the mod, probably JamesV6cdx, to clarify exactly what they did