Wideband start up reading

[Marco]

I'm new to the forum and very new to using and reading the wideband & egt gauge in my RB25 powered S13. I have a couple of questions below.
1- On ignition power only after the wideband warms up should it have a fairly static lambda/afr reading if so what should it be?
2- Possibly linked with above I am finding very inconsistant readings on cruise.

Is there a test I can do of the unit/wiring to see if all is ok or whether I have any faults?

[gunni]

What are the readings and how inconsistent

[Marco]

I think it will be best if i can upload a video tomorrow showing what I mean.

With the ignition on it is reading anywhere between 12 and 20 AFR and it is very very irratic I tried to toggle to lamda but I don't think this will show until it is running as the dec point doesn't move when changing readings...

[Marco]

Here is a link to the start up video what do you think? Is it normal also whilst changing readings the top reading never alters.


http://www.youtube.com/watch?v=3S_sI6hGoow

[[email protected]]

What is the engine doing while you're videoing the gauge?

[Marco]

Rob

This is at ignition on only engine not running.I will take the car for a run tonight and record an actual run on and off boost and on idle.The AVCR boost controller is next to the vems so i will be able to show both boost/revs and the vems at the same time. I'm on the look out for a laptop so I can get more info logged. I'm concerned that there is a fault with something though...

Ps I've just watched a youtube video of a saab with the same wideband and even though his afr reading was up and down it was only within a 4 or 5 digits mine jumps from 10 to 30....

[[email protected]]

Yeah... if theres no combustion then you should see a free air reading up around 19 to 22 nothing down as low as we're seeing there.

I am wondering if you've got the wires all correct - they like to have a thick wire and a thin wire of the same colour (god only knows why), and I've seen erratic readings when a wire came adrift from the plug.

[Marco]

The gauge has been in the car for over a year and was working fine when I bought the car a couple of months ago. On boost I was seeing between 10.5 and 12 approx and at cruise 15 in AFR's, it is only recently that it has become inaccurate. I will check the wires tonight to see if any have come adrift...

[[email protected]]

It could be just that the sensor has died.  You've not used leaded fuel or had any oil seal problems have you?

[Marco]

Neither, the car has been running fine. How do I check for a dead or failing sensor Rob it's expensive to find out it wasn't the sensor If i buy another one and still have the same problem. if so I guess below is what I need?

http://shop.vems.hu/catalog/product_info.php?cPath=1_12&products_id=37

[Marco]

Here's a few video's from tonight. not the best quality but they show the variation in readings i'm seeing..

http://www.youtube.com/watch?v=7-sHIvcaAj8
http://www.youtube.com/watch?v=FoVdgtRS4Rg
http://www.youtube.com/watch?v=IWkWW5TVufI
http://www.youtube.com/watch?v=9H4X3BNfuQw

The first one is when on idle, the others are out on a run. Lambda is all over the place from 0.5 into double figures. do you think the sensor is the problem from these clips?

Edit, My Fc commander is taking the narrow band signal from the sensor so am I right in thinking fueling will be all over at the moment It does seem to be running quite rich recently?

[gunni]

For sure the sensor or wiring problem, go over all the wires. And if they check out get another sensor.

[[email protected]]

You should definitely stop the PowerFC from running in feedback mode.

[Marco]

You should definitely stop the PowerFC from running in feedback mode.

Now that sounds a bit technical for me Rob, can you explain further please? Do you mean just turned off whilst the problem with the vems is resolved as it is providing the signal to the Fc?

Quote below from the power Fc page for the ECR33 skyline
"If you have 0/2 Feedback turned off the PowerFC will not enter its closed loop feedback mode and will waste fuel and be very un-economical. Expect bad fuel economy"

Ps, the new sensor I've just got gives exactly the same irratic readings when the ignition is turned on but not the engine running so i'm going to bet the one i've sent you is fine..
The vems unit is making a charging type sound going up in pitch then down then up is this normal?

Also i've just noticed as soon as the ignition is turned on the gauge flashes "E" for a split second before going to warm up mode "H"  and it doesn't seem to show a lamda reading only an AFR and under that a 4 digit reading ? again is this normal?

[[email protected]]

You should definitely stop the PowerFC from running in feedback mode.

Now that sounds a bit technical for me Rob, can you explain further please? Do you mean just turned off whilst the problem with the vems is resolved as it is providing the signal to the Fc?

In a nutshell, Yes.

Quote below from the power Fc page for the ECR33 skyline
"If you have 0/2 Feedback turned off the PowerFC will not enter its closed loop feedback mode and will waste fuel and be very un-economical. Expect bad fuel economy"

This will be only at part throttle and low RPM - such as when you are cruising. Once things get interesting the ECU will go out of feed back mode. Lambda sensors came about so that
catalytic converters would work, the newer wideband ones are an evolution as a result of greater emissions control.

Ps, the new sensor I've just got gives exactly the same irratic readings when the ignition is turned on but not the engine running so i'm going to bet the one i've sent you is fine..
The vems unit is making a charging type sound going up in pitch then down then up is this normal?

Yes, it reminds me of the noise you get when a camera flash is charging up.

Also i've just noticed as soon as the ignition is turned on the gauge flashes "E" for a split second before going to warm up mode "H"  and it doesn't seem to show a lamda reading only an AFR and under that a 4 digit reading ? again is this normal?

That seems wrong, it should be H first and then jump into a reading once the thing is hot, this really sounds like the one I put on an engine dyno where the action of clipping and un-
clipping the sensor caused a wire to come out.

While this is not an impossability, it's very uncommon for a gauge to break, the ones that fail do so on their first test. But the fact that the reading is rubbish while you're
pressing the button seems way too strange.