No power to 1 & 4 injector

[Gerg]

I recently changed the motor in my 1990 laser, and I have been fighting electrical problems ever since. I changed both the fuse box harness and the harness going to the ecu. The car will start but it is only running on two cylinders. I unplugged all of the injector clips and tested them with a multimeter.

The 4 injector doesn't show any sort of voltage.
The 3 injector shows .40
The 2 injector shows 1.10
The 1 injector shows .00

I tried to swap out the injector resistor pack, ecu, and mpi relay however this didn't change anything. Any ideas of what to check to see where the problem may be at?

 

[donniekak]

Are you testing each terminal in the injector clip in reference to ground, or just putting the probes in each terminal atdhe same time?

 

[Gerg]

Are you testing each terminal in the injector clip in reference to ground, or just putting the probes in each terminal atdhe same time?

Edit: I just checked each terminal with the one probe grounded. I picked up 12.1x volts on each terminal except for on the 2nd injector plug. I got 10.1x volts on one of the terminals.

 

[92AWDHX40]

Sounds like you may have to recheck all the wiring that's the problem when you start messing with the wires, something is bound to go problematic. Recheck the installation.

 

[Gerg]

Well I just re checked all my wiring connections, I unplugged them and made sure all the surfaces were free of any corrosion.

Since I re checked and saw that all the terminals had power going to them i'm going to switch the injectors from the 2 and 3 cylinders and check them on the 1st and 4th injector plugs. This will hopefully tell me if it is the injector plugs or the injectors them selves. I also heard that I can check the injectors with a 9 volt battery, but I'm unsure of this method. I'll check back once I test the injectors.

 

[donniekak]

Have you checked for spark? Usually running on 2 cylinders indicates a power transistor, or coil issue.

 

[chris00326]

Have you checked for spark? Usually running on 2 cylinders indicates a power transistor, or coil issue.

Id have to agree with that. it could also be cam angle sensor.

 

[Gerg]

Can I check the spark just using the multimeter and having the car powered on? I cant really check to see if it actually sparks by myself.

Also how can I check the CAS?

 

[donniekak]

It's easy to check for spark with a timing light.

 

[Gerg]

It's easy to check for spark with a timing light.

So I checked for spark today, I grabbed the spark plug boot on each of the cylinders. It defiantly has spark .

I can pull the injector clip off of the 2nd injector and it dies out, but when I put the clip on the 1st injector it runs the same as before. Same is for the 3rd injector clip on the 4th injector.

So this rules out the injectors being faulty, I checked the wires going to the CAS with a multimeter and it was good according to the FSM. I'm not very good with wiring, I'm going to try to check the connection to the injector transistor to see if any of that wiring is bad.

 

[chris00326]

Alright ya check resistor pack and if thats fine pull out your ecu and see if it smells funny and inspect the board for burnt broken or leaking transistors.

 

[Colt4G63 also]

Put light those little 192 bulbs in each of the injector harness plugs by bending the contacts on the bulbs out straight and jamming them in there. Then have someone crank the engine while you watch the bulbs blink. If any bulbs don't blink then you have an electrical problem. Take care to jam the bulbs in gently so you don't over stress your injector plugs.

Twelve volts positive ignition power comes into the resistor pack from the MPI relay, branches into four separate resistors (in the pack), then each goes to one terminal of each injector. On the other terminal of each injector, the wires each lead to four seperate pins on the ECU. the ECU supplies the ground pulse to each injector.

The DSMlink wiki shows the wiring diagrams and ECU pinouts in the refrences section.

 

[Gerg]

Put light those little 192 bulbs in each of the injector harness plugs by bending the contacts on the bulbs out straight and jamming them in there. Then have someone crank the engine while you watch the bulbs blink. If any bulbs don't blink then you have an electrical problem. Take care to jam the bulbs in gently so you don't over stress your injector plugs.

Twelve volts positive ignition power comes into the resistor pack from the MPI relay, branches into four separate resistors (in the pack), then each goes to one terminal of each injector. On the other terminal of each injector, the wires each lead to four seperate pins on the ECU. the ECU supplies the ground pulse to each injector.

The DSMlink wiki shows the wiring diagrams and ECU pinouts in the refrences section.

Thanks for your help. You've answered most of my questions now that I've ruled out most everything else. I'll check the connector going into the resistor pack to see if there is any problems with those wires.

When I had the clips in the injectors I didn't feel pulse on either injectors, but the other 2 I could. I'll still try to check it with a bulb by most of the time I just work by myself.

I'll check out the pin outs as well, I feel like I'm going to be pulling the harness again here soon!

Fixed the car today, I swapped the ecu harness for one I pulled at the junk yard. I believe that a ground got shorted out or maybe broke during removal and installation.

It didn't take very long at all, was really easy actually. I guess that might be because I've taken the dash and heater core out quiet a few times.

I feel like a little kid on christmas right now and I haven't even drove it yet. This is the first time I'm actually looking forward to the weekend being over so I can get some plates!