Technical Valid injection times

[woj]

Hi,

Although this is not strictly Cinq/Sei the engine is from the same family (don't dare to say similar ). To the point:

I am in the process of decoding 1.2 MPI engine from Punto75 ECU program. Fueling is what I am struggling with right now. What would you say be valid injection times for this engine. Assuming the same conversion formulas as in the 16F technical documentation that can be found here, it won't go over 128ms, and no lower than 0.3 ms. The lower value seems to be too low for my taste (the code would also indicate there is a constant added to all/most injection times). But I do not know enough engines (I do about computers ). So what I am after is valid injection time range for this engine, if you please.

A side question/request: anybody would happen to have the 8F/18F diagnostic interface documentation of any sort? It differs slightly from 6F/16F and this slightly kills me :bang: I expect a 'no' here, but it does not hurt to ask.

Cheers,

Woj

 

[arc]

the min and max injection times will be down to the injectors, no?

 

[woj]

meaning? The ECU opens and closes the injectors for the caculated amount of time. I want to know what I can expect the MPI 1.2 factory ECU to do opening-time-wise with the factory injectors. I guess you mean that in the max case the injector is open the maximum time the injector can handle? /Woj

 

[arc]

yeah, if the injector is pulsed for 0.3ms then that is the min amount of time it takes to energize, open, then close. and if its open for more than 128ms then it'll be operating above 80% duty cycle.

do you want it to go lower than 0.3ms? From what i understand, you can't.

 

[signwerx]

I have a map file from my ecu. It is an MBE file and the mapping software is freely available at sbdev.co.uk

The engine is a 1242mpi from punto 75.

Also, from memory, all the injectors fire together. They are all connected in parallel to the same two wires. Therefore, i would have imagined that the injectors pulse together and lots of small increments at a time, raising in line with the Throttel Position Sensor????????

I will happily stand corrected if i am in completely the wrong field!

 

[arc]

the raise in line with a fuel map grid, which would have revs along the bottom and manifold pressure up the side, using the tps just to time acceleration pulses (needs a load of fuel as you floor it!). unless you use an alpha-n system.. then it will use the TPS and revs instead of the MAP and revs.

 

[woj]

arc: Thanks, so my analysis is not far off then, good to know.

signwerx: yes, they do fire at the same time. That's what all literature I could find about this engine says, and also the ECU program would indicate this.

More importantly: could I have that map file, please? :worship:

Cheers,

Woj

 

[arc]

np. if you browse the 'megasquirt' thread, there are a couple of copies of my map files in there if you want. I ran a 1242 8v mpi on Megasquirt for a year or so before fitting the 1368 16v.

 

[signwerx]

yeah no problem at all. I will be able to get it tomorrow, as i will have to take the laptop to work to plug into the car! (I store the sei in my workshop)

I will send it over if you can give me an email address.

In the meantime, you will need to download easymap from sbdev.co.uk

My map will be right for the engine, however i have 200cc injectors instead of 143cc, the cam is very lumpy and the compression is much higher. My engine idles at around 1500rpm, otherwise it cut out on me.

I hope it will be a start for you anyway!

Adam

 

[woj]

signwerx: check your pm for email. But from what I understand from your messages, this is not a map file for the stock ECU?

I just downloaded the program. Have some problems with it, says that user profile information is missing and exists... ?

/Woj

 

[signwerx]

Hi Woj,

it isnt a map file for the standard ecu, but it will give you all the figures for the fuelling and everything.

I dont understand the error message, the software runs fine on both XP and VIsta for me.

 

[woj]

The program runs fine for me too now, something to do with my XP installation. /Woj

 

[woj]

Can I ask a theoretical question: analysing the program it seems that the injector opening time is limited by the engine speed to one full engine rotation. That is, if say, the engine revs at 6000rpm one rotation takes 10ms. The ECU program seems to limit the time of opening of the injectors to these 10ms (given the required injection time for the current engine conditions require more than 10ms). Does this sound right? I would guess it reopens the injector right away on the next rotation for the next 10ms, so that it is practically open all the time on high load, but it constantly ticks. Does this sound right?

Cheers,

Woj