Does the ECU care about Injector Resistance?
08-24-07 | 04:03 PM
#1
Thread Starter
Senior Member
Joined: Jun 2003
Posts: 434
Likes: 5
From: Regina, SK
Does the ECU care about Injector Resistance?
I just finished my S5 JDM TII into S4 N/A swap, but they sent me an S4 ECU instead of an S5 ECU. However, this was good because I am using the S4 N/A harness.
They sent an N340 ECU, but the car will turn over and sound like it is sorta catching, but won't fire up. I put in my S4 N/A ECU and it works just fine. I was wondering if perhaps the N340 is for a S4 High Impedance car...but I am unsure if the ECU would even care about the resistance and it was just the resistor pack. I have cut the resistor pack out and soldered the wires together.
Any information is appreciated!
They sent an N340 ECU, but the car will turn over and sound like it is sorta catching, but won't fire up. I put in my S4 N/A ECU and it works just fine. I was wondering if perhaps the N340 is for a S4 High Impedance car...but I am unsure if the ECU would even care about the resistance and it was just the resistor pack. I have cut the resistor pack out and soldered the wires together.
Any information is appreciated!
08-24-07 | 06:41 PM
#2
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 23
From: FORT WORTH, TEXAS,USA
The ECU DOES care about seeing an impedence of approx 10-12 ohms on the wire for each injector.
Mazda did this two ways. On early cars with injectors of 2-3 ohms resistance they installed a solenoid resistor package that added 6ohms to each injector feed wire to give a total of approx 8-9 ohms resistance on each injector wire to the ECU.
On later cars they used injectors of 10-12 ohms resistance with NO solenoid resistor on the wire for each injector.
The *drivers* in the ECU will probably burn up someday under full throttle if you use a low impedence injector with no resistor inline. I'm saying the thing will work for some time before burning the injector driver out in the ECU.
It matters. The resistance that is.
IN other words my 87 Turbo car came with resistors inline with the injectors. But I can also run a N333 as long as I still have the resistors inline with my low impedence injectors.
There's no such thing as a ECu for low impedence injectors and one for high impedence injectors.
Mazda did this two ways. On early cars with injectors of 2-3 ohms resistance they installed a solenoid resistor package that added 6ohms to each injector feed wire to give a total of approx 8-9 ohms resistance on each injector wire to the ECU.
On later cars they used injectors of 10-12 ohms resistance with NO solenoid resistor on the wire for each injector.
The *drivers* in the ECU will probably burn up someday under full throttle if you use a low impedence injector with no resistor inline. I'm saying the thing will work for some time before burning the injector driver out in the ECU.
It matters. The resistance that is.
IN other words my 87 Turbo car came with resistors inline with the injectors. But I can also run a N333 as long as I still have the resistors inline with my low impedence injectors.
There's no such thing as a ECu for low impedence injectors and one for high impedence injectors.
08-24-07 | 06:53 PM
#4
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 23
From: FORT WORTH, TEXAS,USA
Read this thread: https://www.rx7club.com/forum/showth...highlight=N340
The 340 seems to be an ODDBALL ECU.
I went to the top of the page here and found SEARCH. I did an ADVANCED SEARCH and just put in N340. I found quite a few threads on N340. You will be able to find them also. I won't read all of them because I'm a disinterested party.
The 340 seems to be an ODDBALL ECU.
I went to the top of the page here and found SEARCH. I did an ADVANCED SEARCH and just put in N340. I found quite a few threads on N340. You will be able to find them also. I won't read all of them because I'm a disinterested party.
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