Wiring loom

[Garth]

Need to wire in a Lambda probe to my new Omex 600 ECU before a rolling road session. Can anybody recommend a good person in the SW London/Surrey area?? Thanks. Garth

[Phil B]

Garth,

 

For a R-R mapping session you don't need to wire in a lambda sensor to the Omex 600 ECU. The R-R operator should use a wideband sensor which the 600 can't read (it will read a 3 wire narrowband sensor for fuelling trim when running on light throttle).

 

Presumably you have a boss already welded into your exhaust manifold to take the lambda probe?

 

Which wiring loom are you using for your Omex 600?

 

The one I bought from Omex with my 600 ECU and TB kit for my Zetec, had a flylead already wired in for the lambda sensor. I didn't use this initially but like you needed to install for mapping.

I bought the narrowband lambda sensor and the corresponding plug from Omex (about £60 I think). Then simply follow the wiring diagram using a set of crimp pliers to fit the mating plug half onto the flylead on the harness.

 

Phil

[Garth]

Thanks Phil - I have spoken to the two Steve's and they have recommended having the Lambda re-instated for a R-R session (for emissions particularly) saying the Omex manages the narrow band Lambda very well! (Not sure what the difference between a wide and narrow band are?)

 

I am not sure what loom was used with my Omex - the work was done by HWR on my Sigma and they took out my MBE ECU and wired in the Omex - I will ask them if they used a standard 'extension' from Omex. I had asked them to keep the Lambda but it got lost somewhere in the process and they are in Newcastle, so I am not going to be dropping by!

 

My old ECU had a lambda connected so I have the boss in the Cat and bypass!

 

The other thing I would like to get sorted out is the big clump of wires (suggesting a standard exrtension?) bunched up next to the ECU - it does not look good, so would like to get that sorted if possible?

 

Edited by - Garth on 21 Jun 2013 16:14:59

[Phil B]

Garth,

The 2 Steves did my mapping and they're right, the Omex 600 does do a good job of fuel trimming on narrowband.

 

The difference is that narrowband monitors Oxygen in the exhaust over a narrow measurement range so all it can tell is too rich or too weak and send a trim down or up signal. This is a closed loop process and fine for light throttle/low load conditions.

Wideband provides a real time measurement of oxygen level so the R-R operator can set the fuelling/ignition map where he wants it for fuel efficiency vs power. More powerful ECUs can use this to "self-map", but not the Omex 600.

 

From what you describe as a bundle of wires, it sounds to me as if you may have the standard Omex loom. Are they shrink wrapped, or actually loose wires? If they are wrapped then each limb of the loom has a yellow sleeve with the name of what that limb does. There should be one that says Lambda, or O2 sensor. It may have a connector on the end, or the wires may just be tapped over. If you can locate that, then you can do as I did. But you will need to buy a lambda sensor.

 

I have the Omex 600 manual which has a wiring diagram, so if you want to tidy up the bundle you (or somebody) will at least know what each wire does and where it goes in the main loom/ECU plug.

 

My solution for the spare wiring was to put the whole ECU along with the spare cable into a waterproof box screwed to the scuttle.

 

Phil

 

 

[Garth]

Phil - thanks for your helpful comments - can I assume from your comments that cheaper ECU's will generally run a narrow band lambda? I guess my old MBE would have run a narrow band then?

 

I will look more closely at my bundle of wires as soon as possible (and 'un-bundle' it if necessary!), but if my memory serves me correctly then it did look as though the wires were shrink wrapped.

 

I will be in touch about your Omex manual if necessary thanks. Garth

[Phil B]

Garth,

 

I'm no ECU expert!

I've installed and run my Zetec on Omex 200 (carbs) and Omex 600 (TBs). I've also read the Dave Walker Haynes book on engine management systems, so I understand the basic principles.

Narrowband lambda was the first generation as far as in-car installation is concerned. As ECU processing power/speed has progressed and the need for greater engine fuel efficiency and specific power has grown, so ECUs have become smarter, monitoring more engine parameters and adjusting fuelling in real time.

So its fair to say that cheaper/simpler ECUs will be narrowband, in order to provide a second order fuelling trim.

 

Phil

[Garth]

Hi Phil

Got around to looking at the loom today - it is standard Omex with a connection labelled ‘OXY SENSOR’, so it looks like I should be able to just buy the Lambda and plug it in!? I see that the Omex website says that there is a wideband lambda for the 600(with external adaptor – whatever that is?) available? Thanks for your help again. Garth

[Phil B]

Hello Garth,

 

Give Omex a call and see what they suggest, Andy Cornock was a great help to me when i was doing my installation. They won't try to sell you anything you don't need.

 

Phil

[Garth]

Hi Phil

Steve who will do the mapping has said he prefers to work with the narrow ban unit! I will give Andy a call to order the Lambda.