a/f ratio gauge?

[SCOOMER]

could someone please explain the air/fuel ratio gauge as i have just got 1 fitted and i havnt got a igloo! At the moment its doing this:-
a) when accelerating it stays in the green (rich)

b)when cruz^n it bounces from stock all the way round in the RED (lean)
the gauge has 14 leds, 4 lean, 10 stock and 4 rich.

I thought that when cruz^n it would bounce just in the stock?as its trying to adjust again and again etc......?

its just had a engine rebuild and port from ROTEHNICS.

my fd also has a 16bit ECU which also runs richer than the 8bit,so with these mods listed i thought every thing would be A OK and not run in the lean section!

HKS CAT-EXHAUST HIPER
HKS DUMP VALVE
HKS SUPER POWER FLOW FILTERS
AND PORTED.

So wot do u think??????? :confused: :eek: :(

[MikeLMR]

under low boost eg. cruising I would expect it to run rich and then aproach Stoich but still be on the rich side under full boost

[Glenn Butcher]

Hi there Scoomer!

Under load/boost it should stay in the RICH area, it will then go up and down for all other types of driving.

However, I have it on pretty good authority that these gauges are a bit of a waste of time. It will really be something that just gives you an "indication" of whether or not the engine is running RICH enough. i.e. you won't actually know the Air/Fuel ratio figure.

Do you know where the sensor has been installed for the gauge? before or after the turbo? Best before turbo.

The best types of gauges and sensors for this job are of course expensive ones. An EGT (Exhaust Gas Temperature) sensor, and a proper Wide Band Lambda sensor. Like those of which you can get with a www.motec.com.au set-up. Using this type of equipment is also the best way to tune a car (on a chassis dyno, or an engine dyno).

[Fish]

Glenn, Motec use two types of lambda sensor.

One I cant remember, but the other is the Bosch LSM11. I have been using one on my boinger for some time. From this I have an A/F gauge connected, which was also linked in to my Motec.

Checking the gauge against what the Motec was telling me, was within .1v.

But remember that there are two types of lambda sensors. Normal and Wide Band. Normal is good for off boost, cruising and wide band is for WOT. Wide band looses details when running at cruise.

From memory Gary Marks black beast has two lambda's. I would imagine that one is normal and the other is a wide band.

Dan

[Glenn Butcher]

Hi Dan,

Done a bit of looking around, for Lambda inputs the M800 ECU can have Narrow Band and High Speed Wide Band input.

The High Speed Wide Band input is an optional upgrade (cost), where the Narrow Band comes standard on the M800.

The High Speed Wide Band's sensors can be NTK, UEGO, Bosch LSU. Not exactly sure of the differences between them?

I think the Wide Band sensors the Heated type?

I also recall that there is an upgrade available for twin Wide Band inputs for V8's etc..


I'm trying to find out some more info. on this from CPC in Sydney. I actually purchased a complete M800 for a turbo car in (Chris Wilson's) and I know I got these goodies also.

It is anoying that on MoTeC's site they don't actually list all their products (Sensors etc.).


Who did the installation of your system again (think I asked before) - do you have an EGT also?

[Fish]

Glenn, a friend made the loom adapter, so that it was just plag and pray.

I had an EGT probe about 1 inch after the exhaust housing, and temps never went over 900c.

Dan

[Glenn Butcher]

From a good friend of mine in OZ (really knows his stuff)...

Wide band lambda is the most precise & fastest reacting type of O2 sensor that is currently available to tune with. With the notion that it will loose details at cruise is totaly incorrect.

The difference best explained between narrow & wide band is exactly as both names describe:

* Narrow band has a small window of operation best suited to cruise, as all vehicle manufactures use a factory O2 sensor.

* Wide band has a very wide window of operation best suited to all applications that require fast response & accurate readings.

Finally, remember that your readings are only as good as the condition of your sensor, & O2 sensors have a limited life span for fast effecient operation.

Great info. there - makes sense also.