Stock 440cc injector latency (dead / lag time)?

[assassin10000]

I spent the last 3-4 hours searching here & google and haven't been able to find out what the stock 440cc injector latency (dead/lag time) is. Anyone here got an injector test sheet from having theirs cleaned with this info? Or a link to a thread I failed completely at finding?

Thanks,
Andrew

 

[assassin10000]

Bueller?




Getting ready to setup a standalone and was hoping someone here would have the info. Maybe I should try and post it in the engine management forum?

Andrew

 

[PHILLYSUPRA]

if you're referring to injector pulse width ( or time open in Ms) , average injector pulse width is around 1.2 to 1.5Ms @ idle. but it all depends on the condition of your injectors and the internal mechanical resistance and it also depends on on the condition of your wiring. the 440's are low impedance and there are quite a few things that can affect injector pulse width. i'd say, by the time any of us are ready to go standalone we are going to bigger injectors anyway which already come with all the specs you'd need.

 

[assassin10000]

No, not looking for pulse width (the amount of time the injectors stay open). But dead/lag time or latency, which is the amount of time it takes the injectors to 'respond' or actually open at different voltages.

Andrew

 

[PHILLYSUPRA]

well, im not sure how to help out then. all injectors are ground side switched. they receive 12v constant (usually) and are grounded open. only thing i can suggest is getting an o-scope and look at the transistor on/off time then minus that by your pintle hump closing time. mechanical latency is really really low on injectors averaging .2 to.5 Ms

 

[assassin10000]

That also depends on voltage and type of injector. You've also got to take into account at high RPM full throttle the time you have available for the injector to be open can be pretty minimal (also measured in milliseconds). So if you know how long it takes to energize and fully open the injector, you can add it to the equation/compensate for it so the injector opens at the correct time/point. To make the most of that small window of time, instead of maybe spraying the back of a closing/closed intake valve .

I found this on the initial search, but unfortunately it doesn't include the denso 440's we have.
http://injector-rehab.com/shop/lag.html

Andrew

 

[PHILLYSUPRA]

use the nissan skyline gtr ones for ref than. they are the closest low impedance inj's to ours. also iirc 13bt injectors are close to ours too.
i dont like the fact injector lab is using more V to the injectors. we already use low impedance injectors then it comes down to simple circuits where amperage will follow with an increase in voltage if resistance stays the same.
we dont want to fry the injectors... ive always found it easier to tune with 12v and just increase the injector size then remove fuel down low.

 

[assassin10000]

Well, figured I'd add this here. A very helpful guy on toymods (australian forum) was kind enough to do some testing to come up with some figures.

http://www.toymods.org.au/forums/showthread.php?t=64120
More here:
http://www.toymods.org.au/forums/showthread.php?t=64930

Closed (T<ms) below this point no fuel flowed, above this point a small drop of fuel becomes evident
Fuel Flow (T>ms) At this point fuel flowed
Fully Open (T=ms) At This point the injector was fully open and you could see the difference in flow
Coil Saturation Time (T=ms) No difference to fuel flow but this is the point where the injectors are saturated, meaning the magnetic field is at full strength and the current draw is maximum.

Approx Closing time T=ms This was measured with the oscilloscope and only and approximate time was recorded
It was made up of the field collapse & pintle shut time, while testing these measurements were done at coil saturation in practice as the ECU will switch the holding current so the field collapse will be faster giving a faster overall closing time.


Min Hold Current (Off <mA)
Once on the injector will close if the current falls below this level

Pull in Current (On>mA)
The injector will turn on when the current is above this level & this is the ideal holding current level

Max Current I=V/(Z+R) (mA)
This is the max current under test conditions

Andrew