Raising injector impedance.

[stradlater]

I have 7m injectors and the haltech needs minimum of 8ohm. The manual says I can use an injector resistor ballast box, but I can't find such a thing and I think all it is is resistors anyway. Do I jut put a 6 ohm resistor across the plug of the injector to make it higher impedance?

[oldcorollas]

yes, you can, but need to have beefy resistors.. the aluminium finned 15/25watt ones would be good

many cars have injector resistors stock (esp toyota).. usually finned aluminium case between power and injector.

pics in here
http://forums.celicasupra.com/showthread.php?t=32079

[stradlater]

Worth using a box from some car at a wrecker?

[oldcorollas]

sure why not
they don't seem to die too often

i think the ones i have are "Ohmite" brand resistors.. didn't end up using them yet. need 1 for each injector. better to mount on flat alloy as a bigger heatsink

[stradlater]

Was that a joke about them not dying? Sarcasm doesn't work so well via iPhone..

[oldcorollas]

they do?
i thought they were fairly reliable? never actually had to use one

can't do peak n hold in the haltech?

[stradlater]

No that was a question... Do they die or not??? I've never even seen one before so I know nothing about them.

Haltech didn't say anything about peak and hold, I therefore doubt it. I basically need two four cylinder units from a something yeah?

[amichie]

It needs to be in series not across the plug of the injector

[MWP]

Do you know that using a ECU that doesn't handle low impedance injectors (ie doesnt do peak & hold) and using low impedence injectors + resistors will limit your tuning ability?

It'll mainly effect your idle and cruise tuning ability, which = more fuel use if it's a daily.

[stradlater]

I had a feeling that might have been the case.. Thanks.

[stradlater]

I didn't know that it reduced tuning ability....

I don't care about it using more fuel, it's farrerrrrrrrrr from a daily.

But interesting. How does it limit tuning..?

[oldcorollas]

the difference may not be too bad if the injectors are nto stupid sized...
the main issue is for say.. FI motors planning to run big boost, so the NA equiv engine ta idle is maybe 1/3rd that of at WOT...

many cars came standard with low impedance injectors and resistor packs

http://www.autoshop101.com/forms/h22.pdf
page 13 (or similar.. injector driver circuits)

[oldcorollas]

it limits tuning because the minimum opening time is slightly lengthened...

however, the high impedance injectors have a longer minimum opening time than low impedance anyway, so it may not actualyl make much difference in the end..

but for example (numbers pulled out of ass).. say you have 800cc injectors on a 2L motor... minimum injector opening time might be 0.5ms... but your idle tuning is say.. 0.7ms...

it also depends on the resolution of the ECU.. if it can only tune to 0.1ms or can do to 0.01ms etc.. makes a big difference...

but the main issue is the amoutn of fuel injected during the minimum opening time, and if that amoutn exceeds your idle fuel, then it will be rich

[stradlater]

They are only 7mgte stock injectors. With maybe 15psi boost. I will get Indy blues in the future.

[stradlater]

Is that all. Not worried about rich at idle... Overly rich on boost is a different story..