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Paul S

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Formerly Axel

Podland

Do you want the good news or the bad news? Well, the bad news is that I could not get the code to work as intended. The good news is that I go it to work another way.

I initially set it up to fire the injectors twice per cycle into each port as intended by Jean. However, whatever timing I put on the injection, I could not get the cylinders to run anywhere near equal AFRs at idle. My theory is that the second pulse that sits in the port until the inner cylinder valve opens, starts to evaporate, displaces the air and then burns rich.

The best it ran was when the injection point was approx. 80 deg BTDC, but the car was not driveable.

So I then set the car up ala MPi. Firing the injectors once per port per cycle, alternating.

I saw an immediate improvement. I used timing figures similar to those shown in TDs log of the MPi last year.

After a couple of short runs and tweaks to the map it felt good enough to do a logging session. Extract attached.

http://www.jaservices.co.uk/photos/Dual%20...EFI%20Siam1.pdf

There is a long way to go to get the map right so that it gives equal AFRs across the range, but there is nothing that cannot be achieved.

The only down side to setting it up in this fashion is that you cannot stage in additional injectors as originaly intended. The two injector drivers are working at 360 degrees apart. You would need four injector drivers to use alternating and staged injection.

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."


Rod S

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Rural Suffolk

Sorry Paul for being so obviously naive, but when you say "twice per cycle into each port" and later "once per port per cycle alternating", I am confused...
To me a cycle is two engine revolutions but with a normal VR (or similar) sensor on the crank you can only measure one engine revolution, you need a cam pick-up for "per port per cycle" counting ???
I'm sure to be shot down in flames for this post but I can't understand what I've read yet !!!

Sorry,

Rod.

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


Paul S

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Formerly Axel

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On 2nd Feb, 2008 retired said:
Sorry Paul for being so obviously naive, but when you say "twice per cycle into each port" and later "once per port per cycle alternating", I am confused...
To me a cycle is two engine revolutions but with a normal VR (or similar) sensor on the crank you can only measure one engine revolution, you need a cam pick-up for "per port per cycle" counting ???
I'm sure to be shot down in flames for this post but I can't understand what I've read yet !!!

Sorry,

Rod.


You are right and it's me being thick.

I was having trouble getting it to run OK and this was best resolved by re-starting the enigine.

Bugger, back to the drawing board.

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."


Paul S

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I think the plan for tomorrow must be to revert back to the firing of each injector twice a cycle.

I'll see if I can get some datalogs on a variety of fixed injection timing settings to see if there is a way forward.

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."


robert

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uranus

one thing paul is that you are efecting a change ,so thats good .

Bicester scramble ,Medusa enjoyed the trip. https://www.youtube.com/watch?v=Q-7I7-nA19U


Paul S

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Formerly Axel

Podland


On 2nd Feb, 2008 robert said:
one thing paul is that you are efecting a change ,so thats good .


Even more grey hairs, that's for sure.

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."


Rob H

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Formerly British Open Classic

The West Country

Dum question but can you use a cam position sensor with MS? it's got to make life easier hasn't it?

EDIT: I meant MS not MJ

Edited by Rob H on 3rd Feb, 2008.

Isambard Kingdom Brunel said:
Nothing is impossible if you are an Engineer


Paul S

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Formerly Axel

Podland


On 2nd Feb, 2008 Rob H said:
Dum question but can you use a cam position sensor with MJ? it's got to make life easier hasn't it?


You can use a second VR sensor on a cam wheel. I think it would require some additional coding, but would be possible.

I'll still try and get some data from fixed injection timing. If the problem is just at idle and light loads, then we may be able to live with it.

It may be that I've not set something correctly, of course.:$

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."


Rod S

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Rural Suffolk



On 2nd Feb, 2008 Paul S said:

You are right and it's me being thick.

I was having trouble getting it to run OK and this was best resolved by re-starting the enigine.

Bugger, back to the drawing board.


No offence intended there by me, at least you're trying... My Megasquirt is now virtually finished but the Mini is just a pile of bits so far !!

Edited by Rod S on 3rd Feb, 2008.

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


Paul S

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We have been logging all day!

Started by setting up the injectors to fire twice per cycle, once per rev as intended by Jean.

I also disabled EGO control as it was interfering rather than helping at this stage. It will be useful as a trimming tool once we are sorted.

Instead of the table, we started with fixed injection timing, initially at 30 degrees before TDC.

I checked the injection pulse with my timing light and can confirm that the code is doing exactly what it is designed to do.

At idle the AFRs were far apart, but seemed to close up if I revved her.

We then did a log, lowered the setting by 10 degrees, did another log and so on until we got to 10 degrees after TDC and then realised that we were going in the wrong direction.

After lunch and time for the laptop to charge we did logs at 50, 70, 90, 110, 130, 140 and 150 degrees before TDC.

The last two logs were not really useful because the laptop started playing up due to low battery. By then we had the laptop talking to both the MS and the Innovate stuff to ease changing the settings, but it drained the battery very quick.

I think we may be getting somewhere at the higher values.

The attached log shows full throttle at the 130 degree setting. We are finding it difficult to find a point where the AFRs are equal and maybe due to wall wetting we never will, but we seem to be making some progress.

http://www.jaservices.co.uk/photos/Dual%20...Log%20Siam2.pdf

The biggest problem is that my oil leak from the primary gear has re-appeared big time due to having lost the breather take-off on the carb. Despite hooking up a vacuum to a temporary catch tank, it's peeing out and the clutch is now slipping.

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."


Paul S

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Log at 150 degrees attached.

I've only just seen this as I do the driving, but I'm encouraged by it.

http://www.jaservices.co.uk/photos/Dual%20...Log%20Siam3.pdf

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."


Joe C

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Carlos Fandango

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Good stuff!

it seems like the afrs are staying a similar amount apart through out the rev range.

logging snigger...

On 28th Aug, 2011 Kean said:
At the risk of being sigged...

Joe, do you have a photo of your tool?



http://www.turbominis.co.uk/forums/index.p...9064&lastpost=1

https://joe1977.imgbb.com/



jbelanger

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Good to see you're making progress. And I'm glad to read that the code seems to be doing what it should. Even though it was working on the bench, there are always things you can't foresee or reproduce on the bench.

It might be that the simple solution is not going to be precise enough because of wall wetting. That would mean having to go to a cam sensor and using different pulse widths for inner and outer cylinders and/or different injection timing.

And I would think that your setup is pretty close to the optimum in terms of minimizing wall wetting issues. So if you can't find a setting where AFR differences are minimal then it's not very likely that others would either.

Keep up the good work. I'll try to see if I could make a few minimal changes to the code to go to sequential or if I need to make major changes to get it to work.

Jean

http://www.jbperf.com/


Paul S

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Thanks Jean,

I think that main limiting factor at the moment may be the maximum advance of 180 degrees.

It may need to go higher than that at high vacuums.

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."


Rob H

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Formerly British Open Classic

The West Country

On 3rd Feb, 2008 Paul S said:
I think that main limiting factor at the moment may be the maximum advance of 180 degrees.


Can you get round that be retarding it? 179 degrees retard is the same as 181 degrees advance.

Isambard Kingdom Brunel said:
Nothing is impossible if you are an Engineer


Paul S

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Formerly Axel

Podland


On 3rd Feb, 2008 Rob H said:
On 3rd Feb, 2008 Paul S said:
I think that main limiting factor at the moment may be the maximum advance of 180 degrees.


Can you get round that be retarding it? 179 degrees retard is the same as 181 degrees advance.


That's true but I'm not sure that the engine will happily switch from 180 to -179, it will miss a whole injection point.

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."


jbelanger

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I'll have to check but I don't think there is a real limit in the code. It's a limit set in Megatune with the ini file. If you change the limit to go up to 360, I think the code will still work.

Like I said, I'll check the code but you can give it a try in the ini file.

Jean

http://www.jbperf.com/


Bat

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Bermingum

Hi,
Not sure if you know this or if it will be any help, but each MPI injector is connected to the ECU twice????
I could take a look in the ECU to see if there's any clues in there?
Cheers,
Gavin :)

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Paul S

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On 3rd Feb, 2008 jbelanger said:
I'll have to check but I don't think there is a real limit in the code. It's a limit set in Megatune with the ini file. If you change the limit to go up to 360, I think the code will still work.

Like I said, I'll check the code but you can give it a try in the ini file.

Jean


Is this the line to change in the ini file?

" injFixedTiming = scalar , S16, 866, "deg", 0.10000,0.00000,-180.00,180.00, 1"

Edited by Paul S on 3rd Feb, 2008.

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."


Paul S

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Member #: 573
Formerly Axel

Podland


On 3rd Feb, 2008 Bat said:
Hi,
Not sure if you know this or if it will be any help, but each MPI injector is connected to the ECU twice????
I could take a look in the ECU to see if there's any clues in there?
Cheers,
Gavin :)


Thanks, but I'm not sure if that will help with 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."


Bat

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Bermingum

Hi,
I wondered if they were linked inside the ECU?
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


robert

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uranus

ref wall wetting ,
a way to reduce this may be to run a higher fuel pressure and a smaller injector ,

or perhaps an injector designed to provide a finer spray eg the 4 hole ones ?

another thought is the scatter am idea ,which might have a big effect in this sit .

Bicester scramble ,Medusa enjoyed the trip. https://www.youtube.com/watch?v=Q-7I7-nA19U


jbelanger

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On 3rd Feb, 2008 Paul S said:

Is this the line to change in the ini file?

" injFixedTiming = scalar , S16, 866, "deg", 0.10000,0.00000,-180.00,180.00, 1"

That's the one for the fixed timing. The one for the table is:

injection_timingTable = array , S16, 288, [12x12], "deg", 0.10000, 0.00000,-180.00, 180.00, 1 ; * (288 bytes)

Jean

Edited by jbelanger on 3rd Feb, 2008.

http://www.jbperf.com/


Paul S

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Formerly Axel

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On 3rd Feb, 2008 jbelanger said:
On 3rd Feb, 2008 Paul S said:

Is this the line to change in the ini file?

" injFixedTiming = scalar , S16, 866, "deg", 0.10000,0.00000,-180.00,180.00, 1"

That's the one for the fixed timing. The one for the table is:

injection_timingTable = array , S16, 288, [12x12], "deg", 0.10000, 0.00000,-180.00, 180.00, 1 ; * (288 bytes)

Jean


Thanks, Jean

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."


Paul S

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Member #: 573
Formerly Axel

Podland

On 3rd Feb, 2008 robert said:
ref wall wetting ,
a way to reduce this may be to run a higher fuel pressure and a smaller injector ,

or perhaps an injector designed to provide a finer spray eg the 4 hole ones ?

another thought is the scatter am idea ,which might have a big effect in this sit .


I'm actually running four large injectors throughout the rev range, double the standard MPi system. I'll knock it down to two and see if that helps. We can always stage the other two in at higher revs.

The injectors are the "four hole" type.

The other thing that I'm going to try is to lean out the top end and see if the inners come up with the outers. At least if the AFRs were running at 11/13 at WOT and 14/16 at cruise, that would be acceptable for now.

I'm not sure if the scatter cam would help with this setup. It would with the MPi setup.

My theory is that there is always some fuel left over on the walls from the squirt that goes into the outer cylinder, that starts to evaporate and goes into the inner cylinder with the second squirt. I don't think you get as much left over from the second quirt because it has sat in the port and warmed up before the valve opens.

Edited by Paul S on 4th Feb, 2008.

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."

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