Dual Wideband Datalog
Turbo Mini Forums

I've managed to get my first datalog from the car this morning.

This is a test with a carb to establish a baseline and understand the variation of AFR between the inner and outer cylinders. This will then be used to analyse test results from my fuel injection setup and eventually the siamesed code.

Engine Spec:
Naturally aspirated MG Metro 1275
HIF44 and MG Metro inlet manifold
12G940 head, slight mod 33/29 valves
SW5 cam
Metro LCB style manifold
RC40 Exhaust
2.76 Diff
Megasquirt MS2 using MS2/Extra code direct driving coil for ignition

Instrumentation:
Innovate LC-1 Wideband - Outer Cylinders
Innovate LM-1 Wideband - Inner Cylinders
Innovate LM-3 Aux box reading MAP and RPM.

Conditions during test:
Pressure - 991mBar
Temperature - 8 degrees

This is just 20 seconds from a total of about 480. Starting from exiting a junction in second gear, changing into third and then slowly to avoid hitting the truck in front.

Have a look and tell me what you think.

Attachments:

16.47kb

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."

very interesting,

I wonder how much closer the AFR's would be with say a set of twin carbs or a webber on a long manifold

also, on the subject of datalogging...

has anyone seen this lcd touchscreen display for megasquit? it will aparantly datalog onto a USB flash drive before too long. Also the gauges will display as graphs so wo can see what has just happened a bit like a mini datalog.

http://lcdash.wikispaces.com/

rpm signal looks a little spikey?
AFR looks to be OK where it matters
Regards
Dave

Well, i seem to have broken something.

I think the AFRs should be closer at lower revs and I think it may be due to the ground offsets for the instrumentation.

So I fitted a new ground for the supply to the LM-1 and something went pop and it will only run on two cylinders.

The problem appears to be that the new ground was duff due to a poor connection and it seems to have destroyed the coil-pack by grounding the tach signal through the aux box.

Bugger, no more until I can fix it.

Just hope it has not damaged the Megasquirt.

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."

bummer :(

this isn't running EDIS right? so you have a second VB921 in the ecu? have you got the well set ok as they can go pop quite easily if there is too much dwell.

whats the aux box?

if as you say the afrs are offset then it looks like the inners are leaning out slightly with rpm and the outers richening as i'd expect.

Right, no EDIS. I have two VB921s directly driving the Ford coil. They look fine and are still putting out a grounding signal.

The coil pack fuse blew whilst trying to diagnose the problem, so I think it overheated and failed. I've located a new one on eBay just down the road, so hopefully pick it up tomorrow.

The Aux Box is the Innovate LMA-3 that you can use to add external 0-5v signals and has built in RPM, MAP, Thermocouple and Accelerometer.

I would have expected the AFRs to be closer at low revs and diverging as I went faster, but that would mean that the outers were running richer at high speed/load.

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."

Hi,
From what I've read about DIY ECU installs is that the grounding is almost the most critical part of the whole job.
As mentioned by mini13 VB921s are easy to destroy :(
Cheers,
Gavin :)

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I've emailed Bill S about the VB921s.

I can always fit a new one.

But, I don't think that they are the problem.

The tach signal went to ground which meant that the coil was continuously ground and it got very hot.

Grounding the output of the VB921 should not damage it.

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."

Hi,
What's the resistance on your coil pack now?
You should be able to get sparks at the plug just from feeding it with 12v and splashing the negative to ground, careful where you hold the wire though
Cheers,
Gavin :)

VEMs Authorised Installer / Re-seller. K head kits now available!

WB/EGT gauges. Click here for customers write-up

Visit www.doyouneedabrain.co.uk

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oh also, if the dwell is too high the coil pack can go bang.....

i know i fucked a brand new one, it got really hot expanded and cracked braking the windings

I think i ended up with about 1ms running dwell and about 2 cranking, but really it needs setting with a scope to avoid over currenting anything.

if you need any VB's in a hurry i have a couple of spares somewhere.

I'm running 3.5ms and 6.0ms cranking as recommended in the MS2/Extra manual.

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."

I can't find the bit in the manual,

I'm positive that i had to reduce mine from what the manual said after killing the coil, although that was MS1 extra.

very interesting paul ,can you also do your test with the sensors swapped from pipe to pipe easily ?and then repeat the test to check bias?
hope the fault is not expensive .

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

Hi,
Stolen from else where
The Ghetto tuner method of configuring coil dwell/charge time is to start with a rule of thumb: Wasted spark coil packs seem to like 2.5 to 3.8ms.

Start at 2.5 for safety's sake and check you get a spark. If you find that you start to get misfires at higher loads increase the dwell .2 at a time until you hit your redline smoothly.
Cheers,
Gavin :)

VEMs Authorised Installer / Re-seller. K head kits now available!

WB/EGT gauges. Click here for customers write-up

Visit www.doyouneedabrain.co.uk

My Mini build diary

Edited by Paul S on 1st Dec, 2007.

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."

Hi,
Sorry didn't mean to you
Cheers,
Gavin :)

VEMs Authorised Installer / Re-seller. K head kits now available!

WB/EGT gauges. Click here for customers write-up

Visit www.doyouneedabrain.co.uk

My Mini build diary

Interesting and slightly confusing.

I’m guessing the spikes in the map are where / when you changed gear, however you seem to run lean (AFR goes up) now I was always under the impression that SU carbs go rich on the over run (this is definitely the case with my car) strange.

I think I probably need to top up the dashpot.

Mine normally goes rich on the overun but only after a few seconds.

It goes lean on a fast change up, particularly if you are low on oil in the dashpot.

I think robert posted a log a few weeks ago that exhibited similar behavoir.

EDIT: Roberts log:

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=176582

Edited by Paul S on 1st Dec, 2007.

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 i agree paul perhaps a direct earth to the battery lead for all computer oriented kit ?

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

paul , in case it helps , i had a similar rpm trace off the jolt rpm point ,and i then connected it to the pip out and it was smooth all the way as you can see from my trace you linked ..
oh and really thick 20/50 oil tends to massively reduce the lean gear change sindrome ,and another spacer on the piston rod to limit play in the piston .

Edited by robert on 1st Dec, 2007.

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

Thanks robert, but I do not have the luxury of pip out. No EDIS module with this setup.

It may be a little spikey because of the impending problem. I think I had a bit of a stray strand of earth wire at the aux box connector.

I'm picking up another coil pack in the morning so hopefully I can fix the problem and have another go. Problem is the weather is looking bad tomorrow.
I usually use 90w gear oil in my dashpot!!!

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."

One thing to watch out for is that if you have misfiring, the reported AFR will be leaner than actual due to more air in the exhaust. I'm wondering if it's what we see here. Something around 19:1 would be difficult to light up.

But as mentioned before, grounding is critical.

http://www.jbperf.com/

Well, I've fixed the problem with a new coil pack. The car is now running on four cylinders again.

I've also tidied up my wiring as I think it was my lack of attention to detail in segregating the signals to the Aux Box that caused the problem and the tach feed earthed blowing the coil.

The Aux Box appears undamaged, but I've not connected up the PC yet.

The weather is getting better, so I might just get another log this afternoon.

Watch this space!

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."