Emerald With Oxygen Sensor

[Andy F 0]

Hi guys

 

I am currently making up a loom for the High Comp Mi16 engine with Sandy/Colins ITB's on. I also have one of miles's 4 branch manifolds. As it has a port for an oxygen sensor i was thinking of adding one. Looking at the Emerald manual a standard 306 one which i have, should be in the voltage range it can recieve as an input.

 

I wondered if anyone had any experience using a narrow band sensor to know if its worthwhile?

 

Also i have noted in the Emerald Manual it has a switched earth for the oxygen heater relay but does not give details about it, presumably this means i could use a normal relay and control the heater using the ECU?

 

Thanks

[Anthony 1,000]

Put the wiring in regardless when you're building the loom - it's barely any extra work, and atleast gives you some options later. Remember that a wideband lambda sensor/controller needs the same four wires (signal, power, sensor earth and heater earth), so it's easy to plug in later if you built the wiring into the loom initially.

 

As for the usefulness of a narrowband, it's going to be limited in your application - you don't have a cat or need it for closed-loop emissions, and it's pretty much useless for tuning on the road or letting the ECU auto-tune. It would be of use to give a quick indicator that the fuelling is sensible enough to safely drive to the rolling road for a proper setup, possibly for future diagnostics if you're suspicious of a fuelling issue (eg fuel pump dying or failing FPR), and for MOT emissions you can pretty much just tweek the idle mixture so that it's lambda=14.7 or a touch leaner and it'll pass.

 

That ECU pin will be fine to use to switch the relay - just feed an ignition-switched 12v feed to the other side of the low-current side of the relay, and then the ECU will earth it to energise the relay and turn on the lambda heater. It doesn't strictly speaking have to be ignition-switched positive, but I prefer doing that to ensure that the relay will definitely turn off with the key regardless of the ECU output, and to reduce the number of permanantly live circuits in the engine bay.

[petert 554]

What's wrong with a narrow band sensor? After you've done all the mapping, they're invaluable for everyday driving, whether you have a cat or not. You should be driving around at 14.7:1 (utilising closed loop) at all cruise situations if you want to optimise fuel economy. Its got nothing to do with emissions. It's the perfect mixture. You'd recover the cost of the sensor in the first ten tanks of fuel. As soon as you squeeze that throttle however.....................

 

The standard Motronic 205 O2 heater element gets its power from the injector relay (near the water header tank). Just use any switched relay however. It doesn't need to be controlled by the ECU.

Edited February 12, 2011 by petert

[Andy F 0]

thanks for the replies

 

seems worthwhile adding, so i will add it to my engine loom as i make it up.

 

I thought the reason for the running the heater through the ECU would be it would act as a timer on ignition as i was led to believe that the heater should only run for the first couple of minutes on start up, then the exhuast gases should keep it to temperatures after this?

[welshpug 1,627]

The heater is on all the time the engine runs, it's not on a timer of any kind.

 

Easiest way to wire it up would be to feed it from the same relay as the fuel pump, that's how its wired up in most looms I've come across.

 

The ecu disregards the Lambda when its on the cold start map (i.e till the engine warms up, the lambda will be warm then too)

[Miles 331 1 Cars]

Worth noting that all the ECU feeds are 0v switch so dead easy to loop into anything you want

[Andy F 0]

simple enough to wire up then, pretty much any ignition live will do.

 

Thanks for everyones help