Waveform

Hey dose anybody have a known good CMP CKP waveform for a 2008 Nissan Altima 2.5. I think i have a stretched timing chain and i don't really want to pull the valve cover. I looked on IATN but the latest model with a usable waveform is a 2005, it seems to be different? I can upload what i have but i will have to go to the shop and take a snapshot of the waveform to upload it.

Here are a couple of shots of what I have. I keep getting a P0011 code and some other random weird codes that i think was a bad connection at the computer, but the P0011 I think is the timing chain. Yellow is the Cam actuator, Green is the CKP red is the CMP. It also looks like the cam is moving around without being commanded to. Probably slop in the timing chain.

Hey jim! Thanks for posting your scope captures. I see what you mean about the known good waveforms being different. I think I know why - the sensor signal polarity is reversed. Your capture shows the CMP being 5V most of the time, and pulses to 0V as the reluctor turns. The known good waveforms are the opposite, maintaining 0V most of the time. The CKP is similar, with your capture showing 5V sync notches, but the known good showing 0V notches. I don't have an answer for that one. :lol:

Still, I do see what you mean about the timing shifting around. I've scoped these signals before, and I remember seeing the downswing of the first CMP notch (doesn't matter which cylinder) squarely intersecting a CKP sync notch. The known goods out there support this. For anyone else following along, I marked up one of your captures:



Is this the same thing you were seeing? If so, then I think you're on the right track with a chain problem.

Thank's for your help. I don't really know why my wave form is upside down either. I am convinced that the timing chain is off now. I could not make much sense out of the diagram i was looking at but it is a 3 wire sensor so i have to be on the signal wire right? Also the PID for the actual CMP position at idle is -29 and what i read on Identifix says it should be 0. I don't have as much experience with variable timing as i should. I struggle with CKP CMP waveforms and it seems like when i need a known good i can't find the one i need. So thank you again I'm glad there are people out there willing to help. Maybe I can return the favor someday.