closed loop - is it important?
 

I've been looking at getting a system that can log / display wide-band but it cannot do closed loop. How important is this for performance reliability? I've been told that it's only really needed for emissions and fuel consumption.

Does the haltech use traditional closed-loop (idle,cruise) or Motec style Lamda targetting?

If I have to pay an extra AU$1000 to get this is it worth it?

In case I've still got anyone's attention, can you hook up a knock sensor to a haltech e6k to get it to retard ignition?

Too many questions :)

-pete

There are NO sensors fast enough at the moment to run closed loop in the high power non cruise ranges...

THE ONLY EXCEPTION to this is the EUGO ($4500Aus) sensor used by Autronic which has a direct interface into the ecu and it WILL allow self programming in all ranges (I think MoTeC may also do this?).

This will allow you to set your target a/f ratio across the whole rpm/load map and the ecu will self program itself as you run the engine.

Closed loop operation with conventional Bosch 4 or 3 wire O2 sensors are only fast enough to run "true" closed loop at moderate throttle cruize conditions and many ECU's allow this feature, most then revert to the programmed map when full throttle high load is applied.

Closed loop operation is good if your ECU cannot be programmed fine enough in the cruize ranges and you need to save fuel, if the ecu is accurate like my Autronic unit you set all ranges once and regardless of weather or engine conditions the a/f ratio will stay where you set it...however it does take a lot of fine tunning to achieve this level of accuracy in the fuel metering (and god help you if you like making changes to your engine hardware!) as you will need to retune it for a less restrictive exhaust for example. The closed loop feature would automaticaly compensate for this.

But yeah the closed loop function will only realy work on the cruize settings, it will not stop an engine failure due to poor tunning.

Thanks for your help you really seem to know your stuff. I take it that you don't have that $4500 sensor, that's why you have to retune it every time right?

Hmmm.... wish I could could afford autronic :( Their website is down but last I heard their ECU's are like >3grand

-pete

On my Haltech I run closed loop. If I go over 20% throttle or boost it goes open loop. Are yall saying that this is a waste. because just cruising staying out of boost I get pretty good gas mileage. It does suck having to use a pwm on it though.

You don't need to use a PWM output for the O2 sensor. It has it's own dedicated loom connection (E6K anyhow).

I wouldn't spend a great deal on getting closed loop to work, rather, spend it on the tune in the first place. If you have a sensor that still works (remember, these sensors get slower as they get older), give it a try, but not to correct a bad tune, or you will probably kill a sensor (and your engine??) anyhow. Try just hooking it up and using it in the datalogs for analysis.

Josh