RB25 CAS Problem? No spark

[95_240]

A little history first. I finally got my car running but it was running like crap. It would miss, run rich, and didn't have that much power. At the time it was not throwing any codes. I ordered a new harness from chasebays because mine looked like crap and I thought there could potentially be problems with it. I installed the harness today and the car would not start. It is giving me a code 11 for the cas. I pulled a spark plug and now I'm not getting any spark. I removed the cas and turned it by hand. The injectors are clicking but still no spark. I'm getting 12 volts to one of the wires that go to the cas 5 volts to two of the others and no volts to the last wire. When I check the plug that connects the coil packs to the main harness I'm only getting 12 V to one wire and the other wires stay at zero even when I turn the cas. My question is does the cas send the signal to the computer and then the computer sends the signal to the coil packs. Because if the computer has a problem and throwing the code it would occur from the computer to the cas right? Is there any other way to test it? I tried calling chasebays but they are closed just seeing if anyone has any input.


The number 3 wire is getting 12 V as it should according to the fsm.

Ok. I just tried something else. Page EN-363. Is it wanting me to test terminal 2 and ground. Then terminal 3 and ground. Or tie 2 and 3 together and test that with ground. I tested them separately and got 2.5 V on the number 2 terminal and it stayed at 12 V on the number 3 terminal.

[95_240]

So after testing the cas I don't think that is it. I'm getting 12 V to the coil packs but when I turn the cas the other two wires are only getting about .07 V. Is this right?

[95_240]

I tested the coil signals at the ecu and got .2 V which is in range when cranking. However up at the coils the signal is only .07 V. Is this signal to weak to fire the ignitors? Oh it's a series 2 rb25.

[Darius]

Did you compare your CAS test results with the FSM section on testing the CAS?

[95_240]

Whenever I check the 1 degree and 120 degree signal on the cas I'm getting good results.

I'm not quite sure how to test in the step that says to check voltage between 2, 3, and ground.



I also jumped wires from the positive , ground, and signal from the computer straight to the coilpacks and there is still no spark. I'm still getting low voltage to the signal wire. I'm told that it needs to be between 1 and 5 volts. But I thought that voltage would be for a series 1 checking the wire after the ignitor.

The coilpacks are also brand new oem and they worked before. Does anyone know the way to test series 2 coilpacks? I believe they only show how to test series one in the fsm.

[95_240]

Also should there be 2 relays on the harness one for eccs and one for ignition? Or is there only supposed to be one relay cause that's all this harness has.

Edit: Nevermind the old harness only had one relay as well. It would be tons of help if someone could tell me the voltage they are receiving at the coil pack signal wire when cranking. I would think the voltage would also be the same on the signal wire prior to the ignitor on a series one as well.

Thanks for the help

[gawdzilla]

one easy way to check is to just pull the CAS and spin it by hand with the ignition on. you should feel the injectors clicking and if you pull all the plugs out and leave them in the coils (ground the bodies of the plugs), you will see them sparking. if one works but not the other, it is proably not your CAS

[Darius]

There is no voltage being sent by the ECU to fire the coils. The coil circuits are powered by a common 12V wire and individually grounded in the ECU to fire. When the ECU grounds the circuit for a coil, it causes that coil to discharge its voltage into the plug which creates current as it flows to ground across the gap in the plug and a resulting spark (arc). Therefore, it does not take any voltage from the ECU to run the coils.

Second, you test the voltage between ground and terminal 2 and then ground to terminal 3 with a volt meter. I'm pretty sure you know how to do this. But you should not be getting 2.5V as you have been witnessing. The FSM says you should have either 0.1V or 5V. There is no analog signal with the CAS. It is either triggered at 1* and 120* or not at all.

Gawdzilla - That's what he did and is seeing (injectors pulsing but no spark). I agree with your diagnosis that it is a bad CAS.

[95_240]

Thank you for the explanation on the coil packs. That was very helpful and helped me eliminate that as the problem.

This morning I decided to test a few things. I used my old harness as a reference and the fsm was very helpful as well. I think I solved the problem with the spark. My terminal 1 and terminal 2 wires were backwards. These are the 1 degree and 120 degree signals. I guess they can be backwards and cause the injectors to work but not the coil packs. I notified chasebays of this and I'm sure chase will call me back to see if their diagram was wrong or just a one time error. I only tested one plug and it sparked once but I had to spin the cas for a while. Is this normal or should I be able to spin the cas and it fires multiple times in a short period?

Edit: So I hooked the cas up and cranked it. I got multiple sparks. Yay! Every once in a while I noticed it would not spark briefly. I don't know if it was losing ground or something else. Can a cas slowly go bad causing hiccups or does it usually just crap out completely? The previous problems with my car I attributed to old gas that was in the tank that hasn't burned off but I could be wrong about that.

Also has anyone used Nissan datascan on an rb25 and does the data logging have any info that would allow me to discern if I'm losing spark?