I have only decided to put this up on here as I know anyone running de-cat tends to, at some point run into EML issues. Which is highly annoying and drove me mad after I removed the insides from the cat on my 1.1!
The principle is a simple one and involves to some degree "emulating" an O2 sensor in the line ... the ecu seems to believe that everything is fine!
I have only posted this AFTER I have had the car checked on a friends OBDII live data software and shows that the ECU is logging no fault codes ... The main finding is with this procedure, Bank 1, O2 Sensor 2 shows as Inactive for some reason but seems to not log faults for it ???
This is the Basic wiring diagram for what I have done and anyone who knows about wiring will be able to understand it !
Notice that the wiring colours are wrong for a standard saxo wideband O2 sensor on the diagram .... Now I could be cruel and let you figure it out for yourselves ... but I'm not going to! This is the corrected key for my O2 sensor :- Black = White wires (x2), Blue wire and White wire = Grey wire and Black wire (hope that helps)!
Now onto the materials that you will need :-
1x Roll of black insulating tape (or loom tape) or any colour of your choosing!
1x 1M Ohm resistor, That's 1 Million Ohm's for those who don't know (the higher the quality the better but entirely your own choice)
1x 12 Ohm Ballast type resistor that has to be capable of handling 1 Amp and 12 Watts of current !!!! This is very important or there will be fire !!!!
This part replaces the heater circuit of the O2 sensor so will by nature get HOT, like 50 degrees hot so be careful please and don't touch after running the car ... +/- 5 % units seem to be O.k and is what mine has but don't cheap out on this please as it won't end well!
1x 1uF capacitor, That's 1 micro Farad for the none technicals again
1x length of shrink tubing to make sure joints are well insulated and tidy, if you're not sure what this is, you put it over the joint and then warm it up to shrink it to the correct size!
1x Soldering iron and some good quality solder
That concludes your shopping list
Total cost is around £5 or £6 at a push (that does not include the soldering iron, car or solder)
this is what that lot looks like ready to solder
Note that the 1M Ohm resistor is wired ready for soldering to the capacitor ... this is because these 2 items are wired in parallel not in series.
Also note that the 12 Ohm resistor is the largest one, not the other way around as you would maybe expect
This is as the unit is finished and wrapped in insulating tape, The 12 Ohm resistor as you can see is soldered to the 2x whites (heater wires) and the 1M Ohm resistor is wrapped up with the 1 Micro Farad capacitor, soldered and joints shrink wrapped, in parallel so you can't see them in this picture (I was tight with the photo's ... sorry)! All in all finishes off nice and neatly, This is not the loom from the car, it is however the wiring to the O2 sensor that was cut off leaving the sensor in place so no hole to worry about!
Biggest question I had was this ... where do I put the damn thing?? Well I chose this place as it's nice and neat and has good air space around that Hot resistor
As you can see from the pictures it was fitted with a self tapping screw into the resistor body!
Please If you are unsure of how to complete this job please DON'T ... Hope this small guide helps someone out as it does seem to have stopped my engine light coming on and doesn't appear to log any faults in the ECU and stops the engine backfiring and over fueling as much
Post cat O2 sensor removal (after cat!)
Linear Mode
