Single Point Throttle Body Injectors

[Sprocket]

As there is limited or no information I can find about these injectors, Ive had to experiment with the settings to get it configured some where right.

The Bosch single point throttle body injector is a low impeadance unit. I fitted the 6.8 ohm 50 watt resistor

Injector Settings Menue

'Inj open time @ 13.2v' to 0 (zero) and 'Inj rampup_battfac' tp 4080 to dissable pulse width modulation (PWM) when using the transient surpression diode.

I have set 'Inj effective rampup' to 800, but comes back as 792. This figure is midway between the figures suggested here http://megasquirtavr.sourceforge.net/manual/Detailed.Output.Fuel.html#Config. I cant quite figure out if this is still used when the above two settings are 'dissabled' so set it for this mid way point to be safe.

'battfac' is currently set at 304. I have not altered this from default, and again not sure if its still used with the above settings dissabled

'Injpwm DC %' set to 100 and 'Injpwm peak time' set to 1. Again i think these are not used as PWM has been dissabled with the above settings

'Divider' set to 1 and 'Alternate banks from h[0]' set to 0 only 'Fire banks while crankng' set to All banks.

h[0] table, Injector Outputs Menue

'0' set to 1 and all others set to 0


These settings will get the single injector working. It was odd as I asked earlier in the year but i had little response, thats why I have documented this

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Can any one see any possible problems with these settings, mainly the battfac setting??

What does the  Port injection or throttle body setting in baisic settings actualy change within the VEMS?

I know they are pretty specific to the aplication but any guidance on this subject is greatly apreciated

[rob@vems.co.uk]

The batfac will be used and scaled depending on the supply voltage (vbatt).   The only way to really calibrate the factor is to provide a sufficently large load in order to see what the effect is - if you turn on all electrical equipment that you have in the car and check the lambda (with correction off) you may see the effect of pw change.

Sorry that I missed your setup question, feel free to bump questions that dont get answered

[Sprocket]

Ah right, i'll do that when i put the spot lamps back on the car, that really drains the battery at low rpm

Going back to the Inj effective rampup, is this setting ignored when using the transient surpession diode and the other settings are dissabled?

And in the Constants menue, what is the actual difference in VEMS between the two injection types of port and throttle body, other than the physical difference of the mechanical hardware??

[rob@vems.co.uk]

Injector rampup is used regardless of the transient diode it defines the injectors opening characteristics.
The Port/Throttle injection type is there for backwards compatability with previous versions and has no effect.

[Sprocket]

Well here's something. After going back to a good known configuration with the ramp up time set to 1000us the idle was pulsing. Increasing the ramp up time to 1150us smoothed out the ide no end. I was forgetting that because i am using a resister in series with the injector, its classed as a high impeadance injector?? and as such has a longer ramp up time??

Any thoughts

[rob@vems.co.uk]

It makes sense as the current is being limited so the injector doesnt get the initial large kick to open it so opening time will be slower. 
Are you using the transient suppression diode in the flyback?  You could experiment with using the PWM settings without the resistor and transient suppression diode and see how that gets on.  The only way to really know the injector's characteristics is to use an oscilloscope.  From my point of view I'd find the lowest acceptable ramp-up time by trial and error as its the easiest (although least technical) way of experiementing.