Megasquirt Port Injection Trial
Turbo Mini Forums

Very interesting,
The AFRs are closest at WOT but still 2-3 apart.
About 4-5 apart at cruise though !!!
But what happened at 365-375 secs? From RPM and Vac plots it looks like you had just backed off then accellerated gently (without changing gear) and the inner AFR deviates noticably from the outer for 10 secs.
Then you accelerate a bit harder (by the vac plot) and the AFRs close up again ???

Question, nothing to do with the plots, but why closed loop only above 1300 rpm, is that part of the code or by choice ???

Rod.

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

I think that it is just a quirk of the AFR map that came with the default MS2/extra code. It leans out considerably at lower revs.

Again the 1300 rpm is the default setting.

On the next run, I am going to set the map to 15:1 throughout. We can then see if the inner cylinder AFRs come up a bit. I'm not convinced that they will because there is a fixed time between the injector firing and the inner cylinder inlet valve closing that means there is a fairly consistent supply of fuel to the inners and the outers get the controlled amount.

The default AFR Map:

Edited by Paul S on 21st Jan, 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."

What's your AFR map vertical axis?
Mine defaults to kPa so I'm guessing yours is % of 1bar(a) ???

It would be interesting to do a comparison graph of where the actual outer AFR was compared to what the map said it should have been...

I have a couple of thoughts !

Rod.

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

I've just changed the log file as I had got the legend wrong. It definatley is the Inner cylinders that run rich.

The AFR Map vertical scale is % of 1 bar(a).

A general review of the points show that it is more or less controlling correctly, although it's a bit lean at the lowest revs.

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."

Ooops,

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

There is a lot more fine tuning that can be done to eliminate some of these quirks. For example, the AFR control is only using the "simple" algorithm. It amy be quicker to react if we use the PID instead.

The only reason for these trials at the moment is to de-bug the peripheral systems ready for the siamese code.

Where this information comes in useful is in demonstrating the effects of fixed injection timing. This all helps to build a clearer picture of what is happening and what needs to be done to get it working right.

I am more concerned with the steady state problems at the moment. Transients can be dealt with later.

Anyway, I'm glad you are paying attention. The whole idea of posting this is to get other views.

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."

Watching with interest Paul.

Well done. Great start

paul do you have the option to change the point in crank degrees where the inj open at all ?

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

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."

it would be great if you could just adjust the opening position at different rpm and idealize it at all points to run smoothest ,,then program in to use those points .

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

Well, we are going to sort out a few reamianing issues with the idle etc then tweak the injection setup on the standard code.

I want to try alternating 2 squirts per cycle. I think that the timing is quite close to the MPi setup, so it will be interesting to see the effect on the AFRs.

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."

No mention of me helping at all :(

If this proves to be successful with the siamesed code hopefully i'll be building up a 1275/1293 running the same design inlet manifolds with a GT1752. I think that the current size inlet plenum would be perfectly adequate for a larger bore 10psi turbo, what do you think dad?

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."

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

Actually, your mum has made some soup. I'll do a curry tomorrow.

I'm not predicting when the 998 will go in, there is still a long way to go with proving the injection on the NA1275.

And I'm certainly not telling these guys that it will be ready for Avon - bound to go wrong!

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."

Looking good, been reading the updates with great interest, keep us up dated as to your progress.

mmmm, curry tonight :)

Tried a couple of different setups today.

First tried staging the injectors so that it ran one injector per port at twice the pulse width up to a 3000 rpm then changed over to both injectors.

The theory behind this was that in spreading the period during which the fuel is delivered, more would get into the outer cylinders.

Anyway, it had the oposite effect. The outers ran very lean and the car was undrivable.

This tells me that the first pulse is partly going into the outer cylinder, the rest staying in the port until the second pulse.

This is contrary to what I thought was happening. I thought that the first pulse was getting into the inner cylinder and some carrying over into the outer. This is not the case.

This confirms some earlier calcs that show that at low VE the time of entry from injector to valve was the equivalent of 140-150 degrees of crank rotation.

So scrap that idea.

I then set it up so that it fired the injectors twice per cycle, but alternating so that each port got a pulse once per cycle at 360 degrees from the other port.

I though that this would work now I knew how long it was taking the fuel to get into the cylinders.

Anyway, I eventually got it idle fine with close AFRs on inners and outers. So I took it for a run with Sturgeo holding the laptop.

The datalog is attached. It was fine up to about 2500 rpm under load and then the inners went very lean.

I believe that this is caused by the fact that the time from injector to valve gets shorter with higher VE, so as throttle and rpm increased the fuel moves quicker and most was going into the outer cylinders.

I think that just about completes the trials with the standard MS2/Extra code. The original setup with all injectors firing twice per cycle is the best setup, but nowhere near what I'm looking for.

It is supprising though how well the car runs. It is very torquey and behaves well in traffic, the only problem being the LM-1 reading 9:1 on the inner cylinders and a slight hesitation at cruise.

http://www.jaservices.co.uk/photos/Dual%20...0Log%20EFI2.pdf

Edited by Paul S on 26th Jan, 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."

What flow rate injectors are you using and how many?
I am just finishing my EFI setup with MS extra as well (although it will be throttle body injection with 2 x 440cc injectors)
Very interesting logs.

I'm using four of the Rover MPi injectors MY100460. Two per port.

Mine were tested at 488cc/min.

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."

It sounds like the engine idles OK with all injectors firing once per revolution. Is that right?
Is the lambda stable with this?

It idles OKish, but it's about 16:1 on the outer cylinders and 10:1 on the inners.

I don't think that it would pass an emmissions test.

The only way to get port injection to work is to have a grip of the injection pulse timing, which we do not with the standard MS/2 or MS2/extra code.

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."

THATS A POSITIVE ReSULT THAT YOU GOT IT TO RUN NEAR EVEN MIX OUTERS TO INNERS ,oops caps ,supports the idea that with correct injector timing it will all work ,i wonder what the effect of a scatter cam would be on it as it is .

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