Ego control settings

[Belle400]

Not strictly a landie or Rangie question but do you guys enable this feature?

I have Ms2 in a Tvr with the 3.9 engine, it’s running reasonably well and has been road auto tuned etc but will be dyno tuned soon.

It has a wideband fitted.

I currently have it disabled but just wondered it is a good feature or does it mess with the fuelling too much.

Its mainly a weekend car so fuel consumption although thought about isn’t a priority.

Mine is currently disabled.
 

Thanks in advance.

 

[FridgeFreezer]

You need to be careful how much authority you give it, but in general it's great especially for your MPG on a cruise.

Generally, if your fuel map is pretty bang-on, the authority only needs to be +/-5% so it is making minor tweaks not dragging the map around - and remember it doesn't permanently change the map, it's only tweaking the "live" values.

Setting it to move too much or too quickly can very easily lead to the whole system "hunting".

[Bowie69]

53 minutes ago, FridgeFreezer said:

Setting it to move too much or too quickly can very easily lead to the whole system "hunting".

Yep, disable it at idle....

[Belle400]

here are my settings, am not sure what the ignition events should be set to.

 

[Bowie69]

Controller with is set to 0 at the moment, so not doing anything.

The help icons do give you some guidance, I forget exactly what the steps are.

[FridgeFreezer]

Ignition events per step is how many "bangs" it waits between making adjustments, 32 is quite low/fast (4 engine cycles on a V8)

Step size is how much it's allowed to move the correction at a time

Controller Authority is how far in total it's allowed to stray from the map, with a good map +/-5% or 10% is enough, if you make this too large a bad sensor or reading can pull you too far from the map.

Active above  / below stops it from making EGO adjustments when you're operating in conditions that the lambda sensor isn't appropriate for (especially with a narrowband) ;

• Coolant temp stops it trying to lean things off during cold-start enrichment
• RPM stops it trying to lean your idle off
• Above/below MAP stops it either leaning off your high-load top-of-the-map or richening up your "coast / over-run" bottom-of-map

Hope that helps.

 

[Belle400]

Thanks, im happy with most of it its just the events thats bothering me.

Found this, cant make sense of the formula though.

Ignition Events per Step:

set this to a value that would switch about 4x a second at your average cruising speed.
4 cylinder assume 3500rpm cruise set Ignition Events per Step to : 29

6 cylinder assume 2500rpm cruise set Ignition Events per Step to : 31
8 cylinder assume 2000rpm cruise set Ignition Events per Step to : 33

You can calculate your:

O2 adjustments per second = ((rpm/120) * cylinders) / ignition events per step

[Bowie69]

It's not that important, just setting it to 30 and I am sure it will be fine.

 

[FridgeFreezer]

As Bowie says, it's not critical - set it too low and the thing is trying to make adjustments before the exhaust gas has got down the pipe to the lambda sensor.

The ECU basically goes:

• Read EGO sensor value, if it's not quite right apply one step of correction.
• Wait for the set number of ignition events to happen
• Read EGO sensor value, if it's not quite right apply one step of correction.
• Wait for the set number of ignition events to happen
• etc...

 

[Belle400]

Ok thanks for the advice.

I will try it at 32 and see how it goes.

[FridgeFreezer]

It's an old one but here's a datalog showing EGO correction in action cruising along the motorway:

 

This is with a narrowband O2 sensor - the bottom trace shows O2 sensor voltage in green and EGO correction in red, you can see the red line "steps" up and down in response to the changes of O2 signal, constantly trimming the fuelling.

This saves a surprising amount of fuel, I've had over 20mpg out of both my 4.6's on long motorway stints and neither of them is in a sensible vehicle.

[Belle400]

Thanks, I will run a log the next time I'm out.