Injector Impedance Questions ATTN: Ivan/Peter(parrot)/Banpei

[will_drift_4_food]

My project is a MAP Bluetop 16V. It has blue injectors in it that measure 2.4 ohms each (210cc, I believe). I am not running a resistor pack. My wiring diagrams (for the RHD MAP models) do not show the use of a resistor pack, nor does my harness have a provision for one. Other people I speak with say that low impedance injectors need a resistor pack, but others say that it depends on what the ECU was designed for. I am running the correct ECU (89661-12051, I also have a 89661-12050). The car will often run for a second or two (from the cold start injector I assume), then quit. No codes. Injectors all have constant power (incl. while cranking) and good grounds.

1) Can someone please clarify the injector impedance issue for me?

and

2) Maybe offer a suggestion as to how to actually (visually) test the firing of the injectors? I have discarded the pulsation dampener and plumbed the supply side with -6AN fittings.

Thanks to all in advance,

Jason

[shanemck]

I was told if they are less than 8ohms they are low impedance, is this for the megasquirt? If so i'm havin the same prob.

[gon]

shanemck Wrote:I was told if they are less than 8ohms they are low impedance, is this for the megasquirt? If so i'm havin the same prob.

you are right.
megasquirt does work with low imp injectors.
there are two options for this , either you use pulse width modulation



or you can use an adaptor board
http://www.aeu86.org/viewtopic/tutorial-...e29/t/7516

check the "final notes" on the first post.

I highly recommend the second option, several problems have been reported with using pulse width modulation.

I am using one of these adapter boards without a glich so far.

[gon]

will_drift_4_food Wrote:My project is a MAP Bluetop 16V. It has blue injectors in it that measure 2.4 ohms each (210cc, I believe). I am not running a resistor pack. My wiring diagrams (for the RHD MAP models) do not show the use of a resistor pack, nor does my harness have a provision for one. Other people I speak with say that low impedance injectors need a resistor pack, but others say that it depends on what the ECU was designed for. I am running the correct ECU (89661-12051, I also have a 89661-12050). The car will often run for a second or two (from the cold start injector I assume), then quit. No codes. Injectors all have constant power (incl. while cranking) and good grounds.

1) Can someone please clarify the injector impedance issue for me?

and

2) Maybe offer a suggestion as to how to actually (visually) test the firing of the injectors? I have discarded the pulsation dampener and plumbed the supply side with -6AN fittings.

Thanks to all in advance,

Jason

European Map ECU's work with low res injectores by default, so they don't need to use a resistor pack.

you only need a resistor pack if you ECU is only able to control High Imp inj and your inj are Low Imp. ( weirdly some manufactures do this )

If your using the appropriate ECU / injectors combo you can test the injectors. Take them out of the fuel rail and crank the engine , they should make a clicking noise ( don't forget to disable the fuel pump or you will end up with fuel everywhere)

the noise should be like the one on this video.

you can also test if with the key on running position you have +12v in one of the wires in the plug that connects to the injector

hope it helps

[Ivan141]

Your question about the injector impedance has been answered a few times already, you dont need a resistor pack with the euro MAP ecu, it is designed to work with low impedance.

Your problem sounds familiar though. Check the circuit opening relay. The problem you are experiencing is a classic among hachi-owners. The fuel pump gets 12v directly from the ignitionswitch while cranking, once the engine fires the circuit opening relay is supposed to close to keep the fuel pump powered. Once this fails it will die directly after firing.

You can find the relay beneath the right-hand side kickpanel (on lhd cars anyway). Try running a direct wire from the battery to the fuel pump if you want to be sure this is the problem.

Happy troubleshooting!

[parrot]

Welcome back Jason! I feared for your sanity for a while there.......

As above, you should use the low impedence injectors you have with the correct ECU. Even if you had wrong impedence for the ECU it would run though pretty badly.

I'm with Ivan, check your circuit open relay wiring and also the EFI relay. If you haven't already, download the EFI diagnosis manual from the tech docs and follow the diagnosis flowcharts exactly! Problems in either area will not throw up a code.

[CHACAMAN]

gon Wrote:

shanemck Wrote:I was told if they are less than 8ohms they are low impedance, is this for the megasquirt? If so i'm havin the same prob.

you are right.
megasquirt does work with low imp injectors.
there are two options for this , either you use pulse width modulation



or you can use an adaptor board
http://www.aeu86.org/viewtopic/tutorial-...e29/t/7516

check the "final notes" on the first post.

I highly recommend the second option, several problems have been reported with using pulse width modulation.

I am using one of these adapter boards without a glich so far.

But remember If you are using a MS 3.0 this have the Fly back board installed the old version of the MegaSquirt need a additional Injector
Board

The MegaSquirt 3.0 can Drive Hig or low Injector only setting the PWM

For Example:

If you are running high-impedance injectors (greater than 10 Ohms), then set the:

* PWM Time Threshold to 25.4 msec, and the
* PWM Current Limit (%) to 100%.

# In essence you are disabling the PWM mode. This allows full voltage to the injectors throughout the pulse widths.
# For low-impedance injectors (less than 3 Ohms), you need to limit the current to avoid over heating the injectors. To do this, there is a period of time that you apply full battery voltage [peak] current, then switch over to a lower current-averaged [hold] current, i.e. peak and hold. Alternatively, you can add resistors in series with the injectors. See the Injectors and Fuel Supply section of this manual for more details.

To run low-impedance injectors with the PWM current limit mode, you need to set two parameters - the "PWM Current Limit (%)" and the "PWM Time Threshold (ms)" - both are on the “Constants” page. The current limit % is the percent duty cycle when the current limit is invoked. The time threshold is the amount of time from when the injector is first opened until the current limit is activated.

1. Start with:
* PWM Time Threshold = 1.0 millisecond, and
* PWM Current Limit (%) =
o 30% on a V3 or V3.57 main board (if you have the active flyback circuit installed).
o 30% on a V2.2 main board (if you have the separate flyback board installed).
o 75% on a V2.2 main board (if you do not have the separate flyback board installed).


http://www.megamanual.com/ms2/tune.htm#pwm

i have a 4AG 16V Running Evo Injector 570CC without resistor pack
only the MegaSquirt is driving the injectors

[Diskovod]

Ivan141 Wrote:Your question about the injector impedance has been answered a few times already, you dont need a resistor pack with the euro MAP ecu, it is designed to work with low impedance.

Your problem sounds familiar though. Check the circuit opening relay. The problem you are experiencing is a classic among hachi-owners. The fuel pump gets 12v directly from the ignitionswitch while cranking, once the engine fires the circuit opening relay is supposed to close to keep the fuel pump powered. Once this fails it will die directly after firing.

You can find the relay beneath the right-hand side kickpanel (on lhd cars anyway). Try running a direct wire from the battery to the fuel pump if you want to be sure this is the problem.

Happy troubleshooting!

Meaning that my JDM Map-sensored first gen big port 4AGE won't have any problems if I switch to high-comp AE92 235cc injectors with hi-comp ECU that are designed for 2 Ohms injectors? am I getting it right?

[sergiocharged]

WOW

i was on hardwork vacation for a few months and come again and i see this
let me tell u ppl i dont understand a word that u said

heheh im finishig EFI classes in specially JAPANESE cars(70% in my country)but DAIIIM ur so advance in this kind of theme

i know when u talk about dutycicle,, band width ,pulse
i also test my injectors like the video and with a PIREX to see how much volumen of GASOLINE give in 12 seconds just for fun

but i never use a Mega but i think if i buy one ,ill have the same problem
heheh
good luck

[NoHachi]

Just make sure you buy the latest board design with the extra flyback circuitry components...that way you wont have to worry about injector impedance.

About the level of detail in this topic: we have a lot of engineers on the forum, us people need a hobby too :wink: