Car: Nissan 240SX
Engine: KA-24 4 cylinder
Siemens Deka 630cc injectors, high impedance
Hall trigger mounted in distributor, sensing a 4 window wheel.
CURRENT 9/23/09
I made a new injector harness, and the injectors were replaced with high impedancew units. The ECU is still blowing injector outputs.
it turns out the(previous harness)injector relay was also powering the ignition coil(single msd coil) - I forgot to make a note of that
'''Why are drivers still failing after replacing the injectors and harness?
Is it possible that the ecu was damaged before, and now the (previously un-used) injector outputs were compromised?'''
TIMELINE
1) ECU Installed
Lost a P259 O/P (fan relay)
Lost Inj Ch03 O/P
2)
Move Inj to another O/P
Check Flyback wire, check grounds, all check OK.
Improve/clean engine to chassis grounds.
3)
Lost Inj Ch04 O/P
Re-do Grounds (changed crimps to solder)
4)
Replace Flyback wire from 20 awg to 18 awg
Replace loose resistor box terminals
5)
Lost Inj Ch05 O/P
6)
Lost Inj Ch00 O/P (new cylinder this time)
7)
Replaced injectors with high impedance Siemens 630cc.
Build new injector harness, flyback wire and relay near ecu - all good conections.
- Combine Injectors (Cyl 1,4 to Ch01, Cyl 2,3 to Ch02)
8)
Lost Inj Ch01 or Ch02 O/P (have not seen the car yet)
????????
OLD
ECU #2168 (Order #3255)
Car ran well every day for a week.
Then, one day the Fan output(P259 Ch01) stuck ON, and later, it lost fuel Injector Ch 03 (Pin 20)
I changed the fuel Injector to Ch04, and the Fan to P259 Ch6.
I checked the GND5 connections, they measure 0.1 Ohm between them. Main Ground is 12 awg wire to engine block.
I checked the Flyback wire. The Flyback wire is ran to the 12v input to the Honda resistor box. The resistor box has a common 12v supply, then branches out to the 4 injectors.
Also, I added a wire from the Ignition output (IGBT 20) to the car's OEM Tachometer.
Today, the ecu lost the Injector Ch04 driver
I did three things at the same time to fix it (had no other choice, I do not have any spare FETs left!) -
1) Replace Honda resistor box (with another one that was in a running Honda, the box from the car was put into the running Honda and it is still running.
2) Replaced 20awg flyback wire with an 18awg flyback wire. The 20awg flyback wire was previously tested with a battery and a string of light bulbs.
3) The Honda resistor box had no connector, instead used ECxx terminal pins, pushed onto the resistor box terminals and strain relieved. This time we found the correct connector and installed it.
I (thought) #3 was the problem.
Last week, the ecu lost another FET.Again on cyl #2.
I am going to replace the injector harness, I cannot think of anything else to do. Is it possible that these other FETS were compromised earlier, and the failure was bound to happen anyway?