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Hi all, I'm new to the 3g platform and am a new member here as well. I'm well versed with the 2g however (rebuilt engine and restored), that's not why I'm here though.

I would like to preface this post with a link showing Oscilloscope data I grabbed from the CPS, CKP, and both Coil Pack Signal Wires. All files are titled with their respective wire/item data. Most of the O-scope readings I got were from inside the car at the ECU. I made sure to check for continuity between the ECU wires and their respective engine harness terminations. (On the Cyl 1/3 vid I misspoke and said 1/2)


I had a buddy bring his 2002 2.4 A/T Eclipse to my shop to look it over for a cylinder misfire. Did a full diagnosis and discovered an exhaust valve on cylinder 3 was causing low compression by way of compression/leakdown test. Replaced the head using the cam that came in the new head and the reluctor ring from the old head. Went to crank it over and nothing. So the diagnosis began.

Did a compression test and it came back flawless. I pulled the codes and got a P0340 Camshaft Position Sensor code, checked power and grounds. They were fine. Then I pulled the CPS connector and saw that I was receiving 5 volts. I put my scope on it and got a good looking pulsewave that was very consistent. It was near the end of that day so I called it quits and came back the next day. One thing to note is that My Digital Multimeter was showing 135 Ohms of resistance between the CPS Ground and the negative terminal. I thought this was odd since it lit a test light so I put an analog multimeter on it and it read between .5 and 0 Ohms. My digital meter would read 0 with the key off so maybe there was some rogue currents that my DMM didn't agree with.

Next day I throw my O-Scope on the CPS signal wire to gather video of the sensor pulse and low and behold it started right up, misfiring here and there but running damn good nonetheless, 5 minutes later it died and I tested the spark and got nothing. I also tested fuel and fuel is not the problem here as I can smell it strongly after cranking for a while (didn't bother to get a pressure reading) Since that day it has started up and died within 5 minutes again. Odd. Still throwing the P0340 code even though the video shows the proper pull-down waveform.

I thought, ok I'll go ahead and test the Crank sensor to see if there's a correlation problem, I'm not certain if there is as I was getting a well defined pulsewave, albeit a bit strange looking as it is not pulled down for very long at all. Powers and grounds all looked good as well.

I then tested Power and Grounds to both of the coil packs and they were good so I went back to the ECU to gather pulsewave data. The Cylinder 1/3 coil signal wire was providing a well defined pulsewave of 12 volts and the Cylinder 2/4 coil signal wire gave me nothing. I figured the signal voltage should be 5, not 12. Not certain on that though.

I just need opinions at this point, it seems to me like an ECU problem but I'm not sure where the ECU derives its coil signal from, be it CKP, CPS, or both.
 

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Hi all, I'm new to the 3g platform and am a new member here as well. I'm well versed with the 2g however (rebuilt engine and restored), that's not why I'm here though.

I would like to preface this post with a link showing Oscilloscope data I grabbed from the CPS, CKP, and both Coil Pack Signal Wires. All files are titled with their respective wire/item data. Most of the O-scope readings I got were from inside the car at the ECU. I made sure to check for continuity between the ECU wires and their respective engine harness terminations. (On the Cyl 1/3 vid I misspoke and said 1/2)


I had a buddy bring his 2002 2.4 A/T Eclipse to my shop to look it over for a cylinder misfire. Did a full diagnosis and discovered an exhaust valve on cylinder 3 was causing low compression by way of compression/leakdown test. Replaced the head using the cam that came in the new head and the reluctor ring from the old head. Went to crank it over and nothing. So the diagnosis began.

Did a compression test and it came back flawless. I pulled the codes and got a P0340 Camshaft Position Sensor code, checked power and grounds. They were fine. Then I pulled the CPS connector and saw that I was receiving 5 volts. I put my scope on it and got a good looking pulsewave that was very consistent. It was near the end of that day so I called it quits and came back the next day. One thing to note is that My Digital Multimeter was showing 135 Ohms of resistance between the CPS Ground and the negative terminal. I thought this was odd since it lit a test light so I put an analog multimeter on it and it read between .5 and 0 Ohms. My digital meter would read 0 with the key off so maybe there was some rogue currents that my DMM didn't agree with.

Next day I throw my O-Scope on the CPS signal wire to gather video of the sensor pulse and low and behold it started right up, misfiring here and there but running damn good nonetheless, 5 minutes later it died and I tested the spark and got nothing. I also tested fuel and fuel is not the problem here as I can smell it strongly after cranking for a while (didn't bother to get a pressure reading) Since that day it has started up and died within 5 minutes again. Odd. Still throwing the P0340 code even though the video shows the proper pull-down waveform.

I thought, ok I'll go ahead and test the Crank sensor to see if there's a correlation problem, I'm not certain if there is as I was getting a well defined pulsewave, albeit a bit strange looking as it is not pulled down for very long at all. Powers and grounds all looked good as well.

I then tested Power and Grounds to both of the coil packs and they were good so I went back to the ECU to gather pulsewave data. The Cylinder 1/3 coil signal wire was providing a well defined pulsewave of 12 volts and the Cylinder 2/4 coil signal wire gave me nothing. I figured the signal voltage should be 5, not 12. Not certain on that though.

I just need opinions at this point, it seems to me like an ECU problem but I'm not sure where the ECU derives its coil signal from, be it CKP, CPS, or both.
The crankshaft sensor controls the firing to the coils and I would change the crankshaft sensor and ring first before fixing the ECU which would not show up on codes as ECM failure. I did fix my ECU for $100.00 with lifetime warranty through E-Bay repair services for ECUs and replaced the crankshaft sensor four times already.
 
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