1996 V3 STi Ignition Problem (After Clutch Change)
19 December 2012, 06:54 AM
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1996 V3 STi Ignition Problem (After Clutch Change)
I've searched high and low to try and find the answer to this question, and I realize that using a new forum can be tricky. If I've missed something blatant, please let me know.
Problem: Car will not start after changing the clutch. Car worked fine before clutch change (minus the slipping clutch problem), but now does not start. I changed out the stock clutch and flywheel for a lightened flywheel and a 6 puck ceramic clutch disk, plus a new pressure plate and associated bearings.
Diagnostics Performed/Results Found:
1. Plugs Checked - They were clearly the ones that came with the car originally. After 80 000kms, they are worn out and need replacing. Plugs replaced. Plugs removed from engine, grounded and noted that only the front two plugs were firing during starting. Interestingly enough, when the starter was disengaged (key moved back to run position from start) the rear plugs spark twice or three times, really fast. It seems like they are discharging.
2. Coil Pack Checked - Proper resistances everywhere. It is the dual coil that mounts to the top of the intake manifold.
3. Signal at Coil Pack Checked - Center "hot" is active when the ignition is in run or start. Signal for lower coil (runs both front plugs) is normal. Signal for upper coil (runs back plugs) is absent, except for when the starter is disengaged. Then, the signal is active for two quick bursts. Reflective of when we saw with the rear cylinder spark plugs.
4. Ignitor Checked - All resistances check out. It is the ignitor that mounts to the right (drivers side) fender, just in front of the strut tower.
5. Signal from ECU at Ignitor Checked - Center ground wire grounds out properly. Both signal wires that run to the coil pack have continuity with the connector at the coil pack. Signal from ECU for lower coil (runs the front cylinder plugs) is normal. Signal from ECU for upper coil (runs the rear cylinder plugs) does nothing, until the starter is released. Then, two or three quick pulses. Reflective of the spark plug test.
6. Signal from ECU to Ignitor, at ECU Checked - Same results as 5
7. Wire Harness Continuity between ECU and Ignitor Checked - all wires have continuity.
8. ECU Changed Out - I swapped ECUs and the problem still exists.
9. Fuel System Checked - all cylinders are getting proper fuel.
10. Crank Position Sensor Disconnected - All spark quits, car turns over fine, but clearly does not try to start. Once reconnected, original problem returns.
11. Cam Position Sensor Disconnected - All spark quits, car turns over fine, but clearly does not try to start. Once reconnected, original problem returns.
12. ECU Codes - When everything is connected and the car is turned over, there are no check engine lights and no ECU codes. When ECU put in self diag mode, no codes.
I have some major disadvantages since I live in Canada and have procured this JDM V3 STi. Mostly, no one here has any clue about the car at all, since we did not get any of them. I've had a look through the manuals that i could find online (1993-1996 subaru impreza and 1997-1998 subaru impreza), and my best guesses have been futile. These manuals do not seem to address the STi specifically, and the turbo version they mention is not the STi, but rather the WRX.
What I really don't understand is how in this car, with one crank and one cam position sensor, how only one of the two coils is getting a signal from the ECU to fire the plugs.
Nor do I understand what allows the ECU to differentiate the Cam/Crank signals to figure out which coil to fire.
My mind is blown. I've been at this for almost a month to no avail. Any tips, tricks or ideas are more than welcome.
Problem: Car will not start after changing the clutch. Car worked fine before clutch change (minus the slipping clutch problem), but now does not start. I changed out the stock clutch and flywheel for a lightened flywheel and a 6 puck ceramic clutch disk, plus a new pressure plate and associated bearings.
Diagnostics Performed/Results Found:
1. Plugs Checked - They were clearly the ones that came with the car originally. After 80 000kms, they are worn out and need replacing. Plugs replaced. Plugs removed from engine, grounded and noted that only the front two plugs were firing during starting. Interestingly enough, when the starter was disengaged (key moved back to run position from start) the rear plugs spark twice or three times, really fast. It seems like they are discharging.
2. Coil Pack Checked - Proper resistances everywhere. It is the dual coil that mounts to the top of the intake manifold.
3. Signal at Coil Pack Checked - Center "hot" is active when the ignition is in run or start. Signal for lower coil (runs both front plugs) is normal. Signal for upper coil (runs back plugs) is absent, except for when the starter is disengaged. Then, the signal is active for two quick bursts. Reflective of when we saw with the rear cylinder spark plugs.
4. Ignitor Checked - All resistances check out. It is the ignitor that mounts to the right (drivers side) fender, just in front of the strut tower.
5. Signal from ECU at Ignitor Checked - Center ground wire grounds out properly. Both signal wires that run to the coil pack have continuity with the connector at the coil pack. Signal from ECU for lower coil (runs the front cylinder plugs) is normal. Signal from ECU for upper coil (runs the rear cylinder plugs) does nothing, until the starter is released. Then, two or three quick pulses. Reflective of the spark plug test.
6. Signal from ECU to Ignitor, at ECU Checked - Same results as 5
7. Wire Harness Continuity between ECU and Ignitor Checked - all wires have continuity.
8. ECU Changed Out - I swapped ECUs and the problem still exists.
9. Fuel System Checked - all cylinders are getting proper fuel.
10. Crank Position Sensor Disconnected - All spark quits, car turns over fine, but clearly does not try to start. Once reconnected, original problem returns.
11. Cam Position Sensor Disconnected - All spark quits, car turns over fine, but clearly does not try to start. Once reconnected, original problem returns.
12. ECU Codes - When everything is connected and the car is turned over, there are no check engine lights and no ECU codes. When ECU put in self diag mode, no codes.
I have some major disadvantages since I live in Canada and have procured this JDM V3 STi. Mostly, no one here has any clue about the car at all, since we did not get any of them. I've had a look through the manuals that i could find online (1993-1996 subaru impreza and 1997-1998 subaru impreza), and my best guesses have been futile. These manuals do not seem to address the STi specifically, and the turbo version they mention is not the STi, but rather the WRX.
What I really don't understand is how in this car, with one crank and one cam position sensor, how only one of the two coils is getting a signal from the ECU to fire the plugs.
Nor do I understand what allows the ECU to differentiate the Cam/Crank signals to figure out which coil to fire.
My mind is blown. I've been at this for almost a month to no avail. Any tips, tricks or ideas are more than welcome.
Last edited by Jezzder; 19 December 2012 at 06:59 AM.
20 December 2012, 11:23 PM
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Check ecu earth pin 24 for ignition control also. See here for diagram and pinouts
http://www.brdevelopments.com/docs/MY97ecu.pdf
You've probably done this but make sure no wires are caught inbetween the bell housing and block. Also when you're checking for continuity between the various wires, are you also checking for shorts between other wires in the same harness and shorts between negative and positive also?
Also disconnect the neutral switch, reverse switch and speedo sensor plugs completely then see if she starts. If it does then figure out the problem with that wiring section.
http://www.brdevelopments.com/docs/MY97ecu.pdf
You've probably done this but make sure no wires are caught inbetween the bell housing and block. Also when you're checking for continuity between the various wires, are you also checking for shorts between other wires in the same harness and shorts between negative and positive also?
Also disconnect the neutral switch, reverse switch and speedo sensor plugs completely then see if she starts. If it does then figure out the problem with that wiring section.
