Right then,after reading Stu's article in FF this month I got looking into injector duration.

Am I along the right path in thinking that injectors can only on between 0 and 233 milisecs?

Therefor it you can't leave one on for ages like a tap?

So a bigger injector will give more fuel at the same pulse width becuase of the small working range?

Got Hillier's book two on Engine management and loadsa similar stuff and it doesn't seem to be clear to me.

 

just wind the fuel pressure right up and be done with

 

http://www.injector.com/faq.php#faq2

That kinda answers it about the duty cycle and the 233 thing I was about is shit.

So does in the piccy at the top of page 116,are those numbers in the map the milisecs the injectors are open for?

 

Anymore?

 

i havent seen the mag do a scan and ill tell you what the scale is

some calibration programs use milliseconds and some just use a hex number

it doesnt really matter what the unit it,,, aslong as it can be increased

 

I'm wth you mate, I'll do a scan later on.

So the hex number is just a random number scale from say 0-233?

Nowt to do with miliseconds just a scale?

CheeRS.

 

where have you got 0-233 from? its probable 0-255 which is 11111111 in binary, so suitable for an 8 bit processor

there would be a direct relation between the raw data number and the milli second output

 

if its 0-233 i dont think it would be hex as it would be 563 in decimal

if its hex 255 would be FF

 

sorry all ive wrote can be a ltitle confusing!

remember the time the injector is open is also related to revs! as the engine spins faster, the injector/ecu has less time to inject the correct amount of fuel

 

so basically full throttle = 256 or 1111 1111

and the size of the injector means it allows more fuel to pass through from 0000 0000 to 1111 1111

or am i talking shite

 

hang on,,,, you firstly you would never run an injector flat out,,,

you may want to run it up to a duty cycle (the ratio between its On time and its Off time) 80%

dont worry about the units used it the mapping calibration program!

if you had a small injector (say a standard yellow cosworth) and switched it for 5 milliseconds and you had a gray injector and swtiched it for 5 milliseconds, which injector would pass the most amount of fuel? the gray of cause, so the pulse width of the injector havent changed, but the flow rate has! more fuel

 

och give it 100%

 

heres a fuel map of a speed density mapped pectel t2, the units are milliseconds

 

you know your a geek when you find that quite interesting as i do

 

Hex and binary goes reet over my head.

Cheers for the replys I now understand it.

 

Hi, would'nt binary 001001010101 be 255 hex. where 11111111 is hex ff.


Regards Dave R.

 

255 is decimal, sorry i havent made that clear

 

Hexadecimal Gareth (I know you know)

 

sorry bill cause your right

 

255=Dec, =FF in Hex, = 11111111 in Bin

 

The injector duration is essentially the result of an equation, the value you are quoting is just one element of that.

Typically you will have:
offset which is an adder
scaler which is a multiplier
then loads of other factors such as temperature corrects etc

So from the base table, you look up your 200, you then mutliply it by a scaling factor to convert it to millisecond, then you add in a number of milliseconds offset
(then all the temp correction etc comes in after and alters it again)

To convert this into a % duty cycle, you basically need to then divide it by the amount of time that 1 rpm takes at that point in the map.

 

2 revolutions

 

in hexadecimal you mean, before bill corrects you

 

If its sequential injection yeah

 

of cause chip

 

Cheers lads, understand what you it means now.

 

Read this:

http://www.emeraldm3d.com/ems.htm#topics

It is written by the master, Dave Walker