MSefi.com read only forum (Jan.15,2018)

I am working on this old car;





and i have my vBatt running from 11.80 till 15.30 during runs...

seems to me, this has a big influence on the Injector PW, so i want to test en correct it,
so maybe a lot of other problems will be gone.

my basic start will to be removing the air-filters, put 4 towels in the Throttle bodies and raise the Injector test PW untill i have fuel on the towels?
write down the vBatt and test PW before fuel.

then charge the battery till much more vBatt and to the same test again.

are there more things to look for?

Use a multi meter to read the voltage at the battery as you do it. and also do some tests to see how close the voltage you multi meter reads vs what Megasquirt tells you the battery voltage is. I did this same thing But I pulled my injectors out and bench tested them at different voltages and it made my car run alot smother! It is also nice to compare how close they are to each other mine dont all open quite at the same time. But they fill 500 ML containers almost excatcly the same time!

i know there will be a difference between MS and the real voltage.
but a difference of 0.4 voltage will always be there.
in the end will the MS will look for a difference from 13.2 volt,
meaning a difference from 13.6 real voltage, of 13.2 MS voltage,
the difference will be the same.

in the end it was very straight forward,
the injector will be opend by a magnet, it takes time
and pushed back by a spring.

so if the injector doesn't open complete, it will make a different sound.
even my wife nothised this.

we put the MS on;
injector runs; 6000
injector open time; 1.1
time between; 60

the injectors starts tikking,
and we raised the injector open time with 0.01 till the sound changed
it was very straightforward, at 1.18 volt the sound changed, at 1.19 i saw fuel dripping in
the throttle body.
i went to basic falues and saw the battery voltage at 12.0 with the fuel pump still on.

the same we did will charging the battery, we found 1.14 msec at 12.8 voltage.

so in the end we use 1.1 msec opening time (you can only do 1.0, 1.1 and 1.2)
and a voltage difference of 0.08 msec/voltage.
what i will change till 0.09 and 0.10 msec/voltage during the next tests,
to see what will do the less AFR-change if my fan goes off and make the battery drop 2 volt.

It sounds like you have a good handle on opening time; your concern about varying the PW in regards to voltage is very real. What do you have your Battery Voltage Compensation set to? This, correctly set, should assist you greatly. You'll probably want to watch your AFR while adding load to your system (bright lights and heater fan?) to see which way you need to adjust that. My car only has a 55 amp alternator so, yes, I have also felt the pain of voltage induced injector changes...

-Mike

you're right,
i found out that my injector opening time was 1.1 msec at 13.2 volt.
there wasn't mucht to choose, only 1.0 or 1.2 left, and those are more off.

after setting the injector opening time,
i did some test on load (fan is pulling 2 volt)
and i have it on 0.12 msec/volt correction now,
it still does change the AFR a bit, but on 0.11 and 0.13 it change more,
you have to think about AFR at 14.3 on idle, with AFR at 14.6 with fan on,
i can live with that.

and it was only 10 minutes of work once you find your injector opening time.

and together with 3x less requered fuel and 3x more VE table,
my values are going from 12 to 220 in the VE table,
so i have enoug accuraty to tune and all the fuel drops during low MAP are gone.

Awesome! Those numbers all sound very nice. Other people reading this should take note - careful, methodical setup is essential to logically obtaining a good tune.

-Mike

well, it seems with an english car running on leaded eur 98 with 12.5 bar compression, you have to doubt everyting

like today i have been changing the whole AFR table to 14.7.
it seems with the 98 fuel you have to much fuel if you are running on 13.1 or more,
so i am trying 14.7, 14.5, 14.3, 14.1 troughout the whole week,
changing the VE table, take a few runs an try to find wat the best AFR is for
acceleration.
and ofcourse i will need the same type of approce for the ignition table....

it takes time, you sometimes need to start all over again,
or change everything you ought to know, or trust nothing,
but you'll never be finished tuning

This sounds like an excellent approach. Keep us posted on your progress. Fuel question: eur 98 leaded - how does that compare to US MON & RON? Just curious, it's tough to keep the octane numbers straight re equivalencies...

-Mike

Because of the 8 to 10 point difference noted above, the octane shown in the United States is 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the "regular" gasoline in the US and Canada, is 91-92 in Europe. However most European pumps deliver 95 (RON) as "regular", equivalent to 90-91 US (R+M)/2, and some even deliver 98 (RON) or 100 (RON).

see; http://en.wikipedia.org/wiki/Octane_rating

mine is 98 (RON), what i really need with 12.5 compresion ratio, because on 95 the engine will detonate en run terrible.