High impedance injectors

[mock_glh]

I just got a new set of RC 750cc injectors for a good price but they are high impedance (12.4 ohms). They were originally for an SRT-4. Will these work on my '87 LM system? Has anyone tried them?

[turbovanman²]

Nope, you need low impedance injectors. There might be a way around it but I have no idea.

[Clay]

well, in theory you should be able to put a resistor in parallel with the injector to drop the ohm load........ but I dont know if that will work or not.

[Dusty_Duster]

well, in theory you should be able to put a resistor in parallel with the injector to drop the ohm load........ but I dont know if that will work or not.

In theory that would work for resistance, but we're talking impedance.

It would probably be more complicated that it's worth.

[Clay]

yeah, but since your not varying voltage or frequency that kind of simplifies things down a lot.

also, Honda used to run both high impedance and low impedance injectors. The only difference? when running one set you had to plug in a resistor pack in order to keep the computer happy, but everything works fine that way. So it can be done with out to much fuss.

[mock_glh]

The list of fault codes on Donovan's site shows a 26 code as "peak injector current not reached" but only for '88 and later (SMEC/SBEC). I'm running '87 logic module stuff. Hopefully it won't be bothered by the lower resistance.

I did learn that high impedance injectors have a .5 millisecond increase (2ms vs. 1.5ms) in response time across the board so I may have to add that to the fuel tables.

[Dusty_Duster]

yeah, but since your not varying voltage or frequency that kind of simplifies things down a lot.

also, Honda used to run both high impedance and low impedance injectors. The only difference? when running one set you had to plug in a resistor pack in order to keep the computer happy, but everything works fine that way. So it can be done with out to much fuss.

You are varying the frequency. The duty cycle of the injector is constantly changing.

But if it's been done before with just resistors, why not try it?

[Aries_Turbo]

you might be able to get away with just popping them in. the driver just connects them to ground and then deals with the flyback that is produced by the coils discharging and charging. the honda guys that run dsm low impedance injectors use the resistor pack to raise the total resistance so that the ecu sees a lower current load.

you did mention that there is a difference in latency for the different injectors. you should be able to take care of this with the FuelBatteryOffset table. i believe that this is what this table was for.

Brian

[mock_glh]

From what I've learned, the response time is about 500 microseconds slower than the low impedance injectors. I can just add this to the fuel tables. I talked to a guy at RC Engineering and he said there is nothing to worry about, that I can go ahead and run these and there shouldn't be a problem.:thumb:

[guyd_15]

Here you go Mock

http://www.honda-tech.com/zerothread?id=216710

Later,
Guy

[mock_glh]

I'm doing the opposite of what is described here.
http://www.hondata.com/techinjectorwiring.html

If anything I might have to put a shunt resistor across each pair of injectors to avoid the 26 and 27 codes but only for that. The lower amp load of the high imp injectors wouldn't hurt the drivers.

[mock_glh]

Update! I got them installed and they run great. No resistors, no fault codes. :thumb:

[2.216VTurbo]

Update! I got them installed and they run great. No resistors, no fault codes. :thumb:

Is Irwindale running tomorrow (Thursday the 20th) night:evil: ? A new personal best in the works maybe???

[mock_glh]

If there's any dry road to be seen between now and then so I can do some wideband tuning. Water burnouts don't give a very accurate datalog.