Looking for known good cam/crank waveform
Have a Nissan Cube 1.8 that starts and runs well when warm. Won't start when cold, unless crank sensor is unplugged.
- Cam and crank sensor both new.
- plugs new, condenser new.
- wiring has no opens, shorts, or excessive resistance.
- grounds ok, (including to ECU which is apparently a common ground problem)
- power to coils is 12v when cranking
- No obvious valvetrain or chain noise once running.
- compression is 150, 155, 160, 165
- tries to start when cold, but spark disappears. Have been told that this Nissan ECU will kill spark if timing is off enough ?
Was suggested by a very experienced diagnostic trainer, that the chain may be loose enough that the tensioner, when cold, pulls the chain tight enough that timing is off. And once warm slacks off enough to allow smooth running.
Anyone have a waveform i can compare to ?
I do not have a waveform but I,m willing to bet timing is your issue. I work primarily on European but remember having a Nissan with the same symptoms. The ECU would not allow the vehicle to start if it saw the timing off but with one of the sensors unplugged it ran fine We ended up replacing a stretched chain
Thanks for that. It more or less confirms my suspicion on how the ECU logic works, and why the spark drops out almost immediately when cold. 2 other local shops have had the same symptoms and we were suspecting that was how the ECU startup logic works. This morning i was talking to a 3rd shop with the same symptoms on a MR18DE they had in the bay and a new chain fixed it.
Here is a 2009 Nissan 1.8L MR18DE
Thanks Justin ! Installed Pico 6 and was able to view the file. ( We have an old Modis scanner/scope)
You’re welcome. That’s one thing that’s really nice about pico files, the software is free.
Sorry dont have waveform, but could u post your cold and hot waveforms maybe we can see difference there.
James my guess is the difference between the cold and hot wave-forms if any will be due to the chain being tighter when cold and expanding when hot so I would be interested in seeing this as well since I did not make that comparison on the 2013 NV200 2.0 that we had.
Resolved: While the timing appeared ok on our snapon modus scope function, i still suspected that the timing chain needed to be replaced and wanted to compare waveforms. According to a Nissan dealer tech, the ECU will kill spark when it thinks the timing is off by some threshold. After talking with few other local independent shops who had similar cold start symptoms with nissan 1.8, .. One…