Electrical Gurus needed: 2&3 not firing

[blcknspo0ln]

Ok, where do I start? Bear with me since I am an intense electrical idiot. Cylinders 1&4 fire and 2&3 do not. I have confirmed that the coil pack DOES NOT fire, hence the pair of cylinders not working correctly. I have 150 psi compression across on a freshly re-ringed motor (cold, WOT), verified mechanical timing, verified fuel in all 4 cylinders. I have also spark tested and confirmed that 1&4 fire and 2&3 do not.

Replaced:
-3 different 1G CAS, positioned TDC
-new taylor spark wires
-new NGK BPR7ES @ .028
-swapped to a verified working power transistor
-swapped to a verified working coil pack (plus resistance tested)

-verified working 99 ECU swap

Grounds: Only grounds I know of are the two to the negative post of the battery, which leads to the firewall and trans bellhousing.

After finding this I gave it a go for continuity test (I'm testing for 0 ohms across, right?)

- Coil pin 1 (blue/black) to PT pin 1 (blue/black). CHECK
- Coil pin 2 (blue/red) to PT pin 8 (black/white). CHECK
- PT pin 3 (black) to ground. CHECK

How do I verify? Simply use some really long wire and reach into the cabin at the ECU harness?
- PT pin 2 (brown/red) to ECU pin 23 (brown/red). Did not verify yet
- PT pin 7 (black/blue) to ECU pin 10 (black/blue). Did not verify yet

Some other things I gathered, not too sure of its importance. these tests were done with both plugs unplugged from transistor&coilpack.

Power transistor KEY ON voltage test:
1 - 1.15V
2- 0V
3- 11.8V
4- --
5- 8.3V
6- 0V
7- 0V
8- 0V

Coil pack plug KEY ON voltage test:

blue/red - .96V
blue/black - 0V
blk - 11.8V

CAS plug KEY ON voltage test:

black/yellow : 0V
red/silver: 11.8V
red/silver: 5V
note: I noticed when I accidentally grounded this during the test, the ISC made a lot of whirring noises.???
red/black: 5V

The ISC also does do the whirring sound when the ECU clicks OFF after I remove the key

 

[blcknspo0ln]

update:

I went back to the car and did these tests with both the coil pack plug and transistor plugged in, KEY ON. Are you supposed to test these continuities with the key on? or does it not matter?

- Coil pin 1 (blue/black) to PT pin 1 (blue/black). CHECK
- Coil pin 2 (blue/red) to PT pin 8 (black/white). CHECK , give or take ..2-.3ohms
- PT pin 3 (black) to ground. CHECK

In order to check pin2/23 & pin7/10, I kept KEY ON and the ECU plugged in, ran a long 12 gauge wire and attached one end to a separated pin 23 on the ECU and attached the other end to the multimeter post, the other multimeter post was then connected to pin 2. I did the same thing for pin 7 / ecu 10 combo. Both came back with 0 ohms this way.

- PT pin 2 (brown/red) to ECU pin 23 (brown/red).
- PT pin 7 (black/blue) to ECU pin 10 (black/blue).

Thinking I understand a bit more about the system, I tested it by spinning the CAS and seeing what fired. As expected 1&4 spark per rotation and 2&3 did nothing. According to VFAQ, ECU pin 23 is for cyl 2/3, but on a 6 bolt swap it is 1/4. That being said, I cut the wire on the transistor just to see if that was correct. After I cut it in half and pin 2 / ecu 23 were no longer connected, coils for 1/4 DID NOT fire, as expected.

Going with that, I attached a wire directly from ECU pin 10 (oem for 1/4, swapped to 2/3) to the short end of pin 7. Theoretically running the wire directly to the transistor should give it the correct signal to fire the coil, but it DID NOT. No reaction to this direct hook up

other things to note:
I've noticed that the ISC only buzzes like crazy when something in the system is improperly ground. That being said, the way I have it, it buzzes so I MUST have a short somewhere. Can anyone help point me to where I can find it based on this information?

 

[bojanglesracing]

If it is a ground make sure your grounds are tight and clean. check to see if any grounds may be missing there should be a ground from firewall to the intake. Is that hooked up?

 

[steve]

update:

I went back to the car and did these tests with both the coil pack plug and transistor plugged in, KEY ON. Are you supposed to test these continuities with the key on? or does it not matter?

No you always measure resistance (continuity) with the power off. You measure voltages with it on. The meter works by putting it's own voltage between the two probes and figures out the resistance between the two by the voltage drop. If the two points already have a voltage on them the meter reading will be false and can damage the meter.

So the problem your chasing is 1&4 fire but 2&3 do not. are the ignition wires swapped or did you swap the pairs before the coil (at the ECU or PTM)? Sounds like the ECU to PTM wires aren't swapped from your testing but your voltage readings at the PTM are way off is my manual is correct. (I think you labeled the pins backwards). Also you need the connectors plugged in for the voltage tests which does make it hard to measure. I assume you were measuring the voltages at the connector which is why you reversed the pin numbers. remember is matters which side you looking at.

I need to see if I have a PTM downstairs so I can measure the voltage between the ECU and it when it's triggering the coil and not. Checking that would be the first step, make sure than the ECU is trying to fire the coil. Then you know if you should be seeing anything at the coil to PTM connector.

 

[blcknspo0ln]

Thanks for the info, Steve. Luv2rallye also informed me that resistance measurements are to be taken with the harness unplugged and the key OFF. After I did this, I suspected something was up and remeasured all of the continuity point son luv2rallye's check list. Lo and behold coil 2 - PT pin 8 had about 48 kOHMs of resistance. After doing a buttload of homework, I realized (didn't know what the note meant beforehand) that the black/white of pin 8 goes all the way into the wiring harness all the way up to the smaller harness for the sensors on the firewall! holy crap! It was also noted that black/white turns into blue/red sometime throughout the harness. Instead of tracing and destroying the wiring harness, I did some research on where to find the engine speed detection connector. Again, as noted (but not overly apparent!) luv2rallye states that blackwhite turns into red/blue at the point of the connector! holy crap it dawned on me that while I was 'cleaning' up my engine bay harness to make it look simpler, I cut this connector right off since it was never connected to anything. DOH! Well, I get to connecting the SOB to each other (black/white to red/blue) and rechecked resistance across pin2/pin8 and YES! continuity! Further double checking my find, I plugged the harness in and turned ACC ON and spun the CAS to see if the coil was firing and it DID. Never did I think a small shock from my car could actually bring a smile to my face. I FOUND IT! Of course, not to forget the handful of DSMers on the board that helped me throughout the fiasco. I plugged everything in, rewired the essentials and gave it a go. The engine starts right up Now.. on to dealing with that horrid boost leak that developed