Dual wideband and other stuff
Turbo Mini Forums

So this is just for info based on previous threads on multiple widebands and particularly the newer 4.9 LSUs vs the older 4.2s

There are only a few of us who have data on dual widebands (inners and outers measured seperately) and even less with three (one after the turbo as well).

We may not have posted much data because of the lack of interest in the AFR differences but this might be of interest particularly between the 4.2 LSUs and the newer 4.9s

For the last year I've been running some experimental stuff from Jean which, using the 14point7 controllers, gives me seperate digital displays of th AFRs and also monitors the internal temperatures of the LSUs themselves to see if they are working properly.

My test setup is very crude, I can only monitor the temperatures on the laptop, not the LED displays.

This was the early version I tested

http://forum.jbperf.com/viewtopic.php?f=9&...lit=rod+s#p6976

Latest test version looks a bit more like this



The hardware is all Jean's stuff this time, not my veroboard...

I'll show some more detailed pictures later, the cases are all 3D printing but the main interest really is the differnces between the 4.2 and 4.9 LSUs (as you can see on the photo).

The first two are 4.9 (the newer ones) that should run at 780C and the third a 4.2 (should run at 750C) but the AFRs should be pretty much the same.

Worst difference I've seen between the sample chambers and the 3rd one after the turbo is 0.5 - 1.0 when using just 4.2s.

Mine isn't road legal at he moment so this setup will shortly be on Graham T's (which is road legal) to see some more.

He also has 4.9s in the sample chambers and a 4.2 after the turbo.

Schrödinger's cat - so which one am I ???

Interresting - What do you think is the cause - do you intend to swap the position of the 4.2 to see what happens to the readings?

Schrödinger's cat - so which one am I ???

Rod,

If you swap the sensors on the engine, you don't need to swap them on the SLC carrier which would avoid the need to change the solder jumper. The jumpers are already correct for the sensors. The display would then show the after turbo data in the first or second place instead of the third place (depending which 4.9 you swap the 4.2 for).

Jean

Edited by jbelanger on 15th Sep, 2015.

http://www.jbperf.com/

Schrödinger's cat - so which one am I ???

so rod what does the 4.9 do that the 4.2 doesn't ?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Schrödinger's cat - so which one am I ???

Are you saying those different readings are all taken from the exact same exhaust gas source ?

ie not different cylinders, pipes or locations in the exhaust ?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

thanks rod , i remember now !

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Stevie,

Just to clarify, the readings in order are outer cylinders, inner cylinders, and after the turbo (down near the gearchange).

The inner/outer readings are from LSUs in a pair of sample chamber piped through some small bore tubing off the manifold which dumps into a large tube plumbed into the downpipe after the turbo.

It means the LSUs don't see extreme temperatures and don't see high pressures (pressure beng the largest factor in skewing the readings).

Getting the outer and inner cylinders the same has always been quite easy with the siamese MS-E code.

In fact the outers are slightly rich (ie, the holy grail of port injection is achieved) but the strange thing is the reading after the turbo is high.

It's always been about 0.5 - 1.0 above the average of the others but there seems to be a step change since swapping the pre-turbo ones to 4.9s

Previous theories have been air leaks, sample chambers too close to the head but this new data means more investigation.

Work in progress...

Schrödinger's cat - so which one am I ???

yup, i think ,(with no evidence to back me up) the gases have not settled after combustion to their final state that close to the head ?

i suppose a series of sensors down a downtube would let you know the place where the gas has finished its change of state ,and maybe give you a correction factor , if thats possible with the temp and velocity changing all the time through the rev range .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

If the combustion is not finished, wouldn't that mean that you have more O2 in the gases and you would then read lean (like a misfire)? That's the opposite of what is happening here.

In any case, I look forward to see what the upcoming tests show.

http://www.jbperf.com/

It's worth having a watch of this video (previously posted by Jean):

https://www.youtube.com/watch?v=ueqDFWti47g

From 32 minutes onwards, particularly from 35 minutes.

I'm all for picking the low hanging fruit myself

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

http://www.jbperf.com/

But a misfire and partial combustion are two totally different situations.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

http://www.jbperf.com/

I agree that the leading factor is the presence of O2, but just because combustion is incomplete does not mean that O2 is present or in a state that can be detected by the sensor.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Yes, it's definitely not a static situation as opposed to a misfire where you have an effectively inert mixture of gases.

I'm still not fully convinced that this is the issue but I don't have anything concrete against it or any alternative explanation. So I'll wait for more test results (which I can't perform myself unfortunately).

http://www.jbperf.com/

Let's not get too bent out of shape over this (like happened last year).

I've not really posted any results yet, just a quick photo of the displays.

If we can all take this seriously, there are only a very few of us who can actually provide real data.

So let's stop bickering (did I spell that right ?) and agree a way forward where we are all happy to do the testing and publish the results.

Enough said for the moment.

Schrödinger's cat - so which one am I ???

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Not sure that we will be able to make a comparison with the earlier engine as this is a different engine and injection setup in many ways.

However, I have drilled and tapped the manifold at the head flange so that, once set up, I can transfer a sample tube so that I'm effectively monitoring at the head, 500mm from the head, before the "Y" piece and turbo, plus downstream of the turbo.

That should give us the answers we need.

We've not seen this problem in a real world situation on the road yet, so Graham's data will confirm, or otherwise, if there is an issue.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Perhaps the original thread linked above should be resurrected for general discussion and theory, to help keep this thread uncluttered?

Rod, will the data from my setup (above) be of interest, or is this too far off track?

Schrödinger's cat - so which one am I ???