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Old 11-04-2012, 05:21 PM   #1
koalorka
Scooby Newbie
 
Member#: 221715
Join Date: Aug 2009
Chapter/Region: E. Canada
Location: Canada
Vehicle:
1995 STi Version II

Default EJ20G, no spark. Multimetre diagnostics performed.

So I did some work behind the dash a while back which forced me to disconnect the harness in the cabin and all of the plugs, and also had the intake manifold ported and polished, so I took advantage of the easy access to replace the coolant temp. sensor and knock sensor. Also had the ECU re-tuned to be a little more aggressive.

Now with everything wired up the car cranks but gets no spark. I've verified that it is receiving fuel and that the injectors are opening, so I'm confident it's the ignition system.

I went outside with a multimeter today and performed some basic diagnostic procedures.

Starting with the coil all the way to the ECU, I found the following:

1. Spark test on detached coil did not show any spark. I removed two coils and "dry-tested" them on an old spark plug grounded with the plug threads contacting a ground bolt. No sparking when cranking.

2. Next I disconnected the cables to to engine wiring harness on all 4 coils (E21, E22, E19, E20) and I found they are all receiving power on the ignition coil circuit, 12.3 V reading over the published 10 V minimum on the no. 1 wires.

3. I moved to the ignitor checking the ECU input signal. Here is where it got strange. Subaru recommends a reading of 0.1V to 3.4V on the ignitor from the ECU 5-pin connector B12. The reading I actually got peaked at 0.07V, so considerably less, but it was interrupted, which leads me to think the ECU is sending control signals, but they are not potent enough.

4. Since my tester cables were not long enough to measure the resistance between ECU connector and ignitor connector, I went all the way back to the ECU pin-out and tested the appropriate connector terminals for output signal to the ignitor. I found pins # 10, 9, 8, 7 on connector B44 responsible for ignition control and when I did a test on these while cranking, I got pretty much the same range of values, with a max. peak of about 0.07V from the ECU. So the harness is fine and not shorted, and the ECU appears to be receiving trigger signals from the crank and camshaft position sensors as the signal fluctuates when cranking. But again it is below the specified 0.1V minimum value.

5. I then checked the ECU power supply and it is getting 12 V at all the required pins (12, 13 and 15 on B43) and No. 12 on B95.

So to me, it seems that the ECU is getting what it needs from the cam and crank sensors as the outputs from the ECU to ignition control are intermittent while cranking, but simply below the specified voltage. The ignitor is also fine as it continues to relay these sub-standard trigger signals to the individual coils.

Could it be the grounds?

Would appreciate your thoughts on this.
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Old 11-05-2012, 05:33 AM   #2
pmugabi
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Member#: 280926
Join Date: Apr 2011
Default

Are there any error codes stored on the ECU? If there is an issue with the cam/crank sensors a code will be generated after a few seconds of cranking.

Can you test your newly tuned ECU on another car? It might be corrupted or a pin on the add-on chip might be loose. Can you reconnect jumper J1 and try again?
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Old 11-05-2012, 01:57 PM   #3
koalorka
Scooby Newbie
 
Member#: 221715
Join Date: Aug 2009
Chapter/Region: E. Canada
Location: Canada
Vehicle:
1995 STi Version II

Default

No codes except for 24, which is the IACV and a minor issue which does not influence ignition.

I will check the grounds again and if that fails I'll test it on an unmodified ECU.
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Old 11-05-2012, 02:38 PM   #4
eg33GC
Scooby Specialist
 
Member#: 206851
Join Date: Mar 2009
Chapter/Region: MWSOC
Vehicle:
99 V4
EJ20K RS

Default

a friend is having the same issue with his newly swapped v2 setup, that ran when it was pulled from my car..

although he left his ecu with the cover off sit in his car for a week in direct sunlight
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