vugoodoll

Hello Everyone,

I'm currently troubleshooting starting issues with my newly built 94 SC300 2JZGE NA-T. The car would crank but doesn't start and I found cylinder 4&5 is flooded with fuel. I noticed the injectors number 4&5 always making zapping noise when the ignition is turn to on and eventually get very hot . I know the injectors are good because the zapping noise happen to every injectors that I put in. I have two set of 440cc injectors and a resistor box.

What would be the cause the injector to make constant zapping sound and get very hot? I plan to pull the ECU today and inspect the capacitor. Any suggestion is greatly appreciated!

Thanks in advance!

stockhatch

iTrader: (12)

Check each pin on the injector connectors for 12v with the key on. Make sure you do NOT have 12v across the two pins. You should have 0v across the 2 pins on each injector connector with the key on. It sounds like you have a short on one injector pin and they are going static. How is your resistor box wired up, and what type on injectors are you running?

Correction, you should have 12v on one pin at the injector and 0v on the other to ground. You should have 0v between the pins. With the key on. Sorry. The important part is 0v between the two pins with the key on.

WadeLovell

iTrader: (5)

Go to Autozone and get tool 27161. You will probably use the NOID light labeled GM PFI, as I recall. Test each injector but especially #4 and #5. Stockhatch is likely to be correct. One or more of the injectors sounds like it is arcing due to a short. You can make your own NOID light if there isn't an Autozone near you (I prefer LEDs which respond faster than regular bulbs.) The refundable tool deposit is $25.

vugoodoll

Thanks for quick suggestions guy.

The injectors are 440cc from MK3. The injector box already came with the car and I can tell it seem professional wired. The injectors wiring/resistor box and the map-ecu are the only two things that I see done right on the car. I can tell by the way they shrink wrap the wires =) Everything else is ****ty job.

I test the all six injector connector with a multimeter and NOID light. Here are the result:
Injector#1 - Constant 12v on pin1; pin2 the volt fluctuate from 10v, 6v, 3v, 2v....NO NOID LIGHT!
Injector#2 - Constant 12v on pin1; pin2 the volt fluctuate from 10v, 6v, 3v, 2v....NO NOID LIGHT!
Injector#3 - Constant 12v on pin1; pin2 the volt fluctuate from 10v, 6v, 3v, 2v....NO NOID LIGHT!
Injector#4 - Constant 12v on pin1; pin2 the volt fluctuate from 10v, 6v, 3v, 2v....Flashes NOID LIGHT!
Injector#5 - Constant 12v on pin1; pin2 the volt fluctuate from 10v, 6v, 3v, 2v....Flashes NOID LIGHT!
Injector#6 - Constant 12v on pin1; pin2 the volt fluctuate from 10v, 6v, 3v, 2v....NO NOID LIGHT!

According to the test the injector connector 4&5 are good? Could a bad resistor box caused this?

Thanks again.

stockhatch

iTrader: (12)

When you tested with the noid light, were you cranking the car, letting it sit with the engine off and key on, running engine, etc?

stockhatch

iTrader: (12)

Also, trace it out, and post a diagram of how the resistor pack is wired up. If it is from a MKIII, it may not work correctly with the sequential injector wiring on the 2JZ.

vugoodoll

The ignition key turn to on, no cranking and the engine is not running. This is the first time I'm trying to start the car since the build. I recalled the car have same fued flood in cylinder 4&5 when I first start the build.

Correction, the result on injector connector on 4,5 should be:
Injector#4 - Constant 12v on pin1; pin2 the volt is fluctuate .025 - .03 ..Flashes NOID LIGHT!
Injector#5 - Constant 12v on pin1; pin2 the volt is fluctuate .025 - .03 ..Flashes NOID LIGHT!

Yesterday Test: The connector #4&5 can send fuel out of all injectors. If I take the injector connector #4 or 5 and put on to injector 2, it shoot fuel. It does that for every injector.
Today test: Same test above but the injectors are not shoot fuel but make zapping sound. The NOID light flashes same patern as the zapping sound.

It seem to me that the connector #4,5 is working properly and the rest doesn't.
Questions:
1. Shouldn't the injectors valve be closed all the time even with the ignition key is turn to on?
2. What would be the cause for the 2nd pin on injector to have high fluctating voltage(10v, 6v, 8, 9, 4.3 etc...)? Bad ECU?

stockhatch

iTrader: (12)

If the pin is getting a pwm signal you won't really be able to read that correctly with a cheap digital volt meter. You would need a scope to see it really.

At any rate, the noid light is telling you something useful. If it is flashing, you are obviously opening and closing the injector. With the key on and the engine not running or cranking, you should NOT be getting pulses on the noid light. It should not be lighting up at all unless you are cranking the engine, or the engine is running.

stockhatch

iTrader: (12)

It is possible that you have a bad ecu, but WHY? Maybe something was wired wrong to begin with and replacing the ecu will result in the new one cooking the same way.

I would trace all the injector wiring out for both the ecu signal side, and the power side of each injector. Make sure they go to the correct place on the ECU, and that they are all open and not shorted to ground or 12v.

Also, I would test the resistance for each injector circuit through the resistor pack. Is it a 3 wire 7M pack, or a 6 wire pack? How is it wired?

You can eliminate the ECU as a problem by de-pinning injectors 4 and 5 at the ecu plug. Then turn the key on and see if the injectors still fire. If they do, it is in the wiring, and if they dont, you can suspect the ecu.(make sure they are isolated when you depin them. If they touch ground, the injectors will open)

vugoodoll

I think i found the problem =)

Both board on the ECU is burnt. This seem beyond repair??

stockhatch

iTrader: (12)

Nice one That may be repairable. it depends on whether the traces and pads are intact. if you feel up to it, you could desolder and replace those caps.

Ali SC3

iTrader: (10)

Good find, that should be the problem. The 7m resistor pack works fine on sequential, the trick is to pair companion cylinders together. This way the 3 channel pack acts like a 6 channel, as by the time the companion one fires, the other pulse is long over.

stockhatch

iTrader: (12)

Good point Ali. I wasn't sure on the resistor pack, but that makes sense.

Ali SC3

iTrader: (10)

thanks stockhatch, I had to look it up a long time ago when I was going to use those injectors on my first setup.
you could try removing the caps, cleaning the board with an electrical safe contact cleaner, and replacing them.
there is a vendor that can repair the ecu if you send it to them as well.
A replacement ecu or sending it out may not be a bad idea if you don't want to solder and if you can afford the downtime, but if you want it back on the road asap a trip to the electronics store and a few hours could possibly get it working again.

WadeLovell

iTrader: (5)

There is still a cause and effect question; did the wiring cause the board to burn out or did the board burning out in the ECU cause the wiring to appear faulty?