can anyone verify this or correct the statement?

 

Injectors get their signal from the ECU. But the ECU determines what to give them by the signals it recieves from different sensors, such as throttle position by the TPS, and RPM from the distributor(ignitor). It also passes through a resistor pack(that aluminum heat sink looking box under the hood). It can vary from model/brand, etc, but that is basically what happens. Does that clear it up?

 

To clear it up a little further, the injectors are always hot (+volts). The ECU completes the circuit to ground. The duration, or pulse width, is determined by throttle position, engine temp, and a few other parameters.

 

ok where do they ground to?my injectors arent grounding.

 

just like Perfectionist just said, they ground inside the ECU.

ie the ECU switches them on by completing the circut to ground.

it is hard to understand what you mean by "my injectors arnt grounding"

who told you that? what makes them think that.

what codes is your ECU showing? does your engine crank? do you have spark?

what might have changed since they stoped grounding?

t..

 

Here's a little more info.
The ecu has been tried on another car and it works fine.

The injectors have a constant hot.

The car will run for a few seconds if it is given a shot of starting fluid.

The thermostat housing is sandblasted to bare metal and the ground appears to be in good shape.

Running a jumper wire from the thermostat housing to the neg. side of the battery didn't do anything.

The injectors are not getting a pulsed ground at the injector clips like they should.

There is 4 ohms resistance from the thermostat ground to the neg side of the battery

 

so what codes are you getting?

none?

ground sounds OK, it is your wires from clips to ECU that may be damaged.

check for continuity betwwen the ECU and the clips.

you said the ECU is fine, so it has to be in your wiring harness.

t..

 

k will hopefully be checked tomorow if it dont rain

 

You should be reading 0 ohms if the meter is calibrated correctly. A ground should be a ground, no resistence.

Anyway, even if you're correct, it's not enough to cause your problem. If the ECU works OK on another car like you said, I would check the wiring from the injectors to the ECU. If the injectors do indead have voltage to them, the only other possibility is the injectors themselves aren't working. One caution though... you can read the proper voltage at the injectors through a poor or corroded connection, but the connection cannot deliver enough current and the voltage basically drops to zero. So... check upstream from the injectors too. (resistors, wiring, main relay, ect.)

 

is there any way to make the injectors pulse?maybe a jumper wire

 

I would test the injector resistor pack.

 

Do you have fuel presure?

 

yes fuel pressure is good.

When i was over there i noticed you had a bit of wiring harness laying around. Do you have any extra injector plugs on there? You could rig up a tester with long leads coming from an extra injector plug and see if you could get the injectors to click. I would try this on an injector that you aren't using first, just in case. I still find it very odd that all of the injectors aren't functioning. This would point me to:

1. an entire set of bad injectors (need to be tested) seems unlikely

2. a bad ecu (has been tested)

3. continuity problems from the ecu to all of the injectors from their respective pins ( needs to be tested) seems unlikely that all of them would be bad unless a plug was undone somewhere

4. bad ground cable somewhere on the engine. this seems to be the most likely cause to me. I would take every ground off that I possibly could and reclean the surface, use dielectric grease to promote a good connection, and just for testing purposes use jumper wires from all the grounds directly to the battery.



[Modified by racerxadam, 11:34 PM 11/21/2002]

 

The injector resistor pack has a plug that goes to all the injectors.

 

Do what? Is this a swap?

 

A noid light set comes in handy here....only about $20 for the whole set.

 

owww, whats a noid light set?

 

A noid light plugs into the injector harness and flashes when it gets the proper voltage pulse. About $5 at Pep Boys.

 

or you could use a test light you already have and attach the the clamp lead to 12 volts and probe the ground side of the injector harness while cranking and get the same effect.

 

Good stuff!

 

Is your fuel pump turning on? Always start with the basics

 

hence the pump is turning on


[Modified by racerxadam, 10:35 PM 11/22/2002]