Intermittent Power Loss
 

This issue has been happening the past few days and has me worried. I haven't been able to find anything online specifically relating to what I'm seeing.

I first noticed it when I was driving on the highway a few days ago. I started to hear a strange noise from my exhaust. A louder than normal rumble. About 30 seconds later all the power on the car cut off and back on really fast. This happened 2 or 3 times in quick succession. Even though power seemed to cut out I didn't notice a change in rpm or acceleration. Car seemed to still be driving the same except for the momentarily loss of power.

I tried resetting the ECU and the car seemed to be fine for the next couple of days.

Today on my way to work I started to hear the loud rumble from my exhaust again while on the highway. I decided to try and down shift into 5th gear to see what happened. This caused the car to momentarily lose power again, but the exhaust noise went away. A few minutes later the noise started to come back and I down shifted as soon as I heard it an the noise went away without power cutting out this time, so I shifted back into 6th gear. A few minutes later I heard the exhaust noise again, so I let it go a little longer this time before I downshifted to 5th gear. This time the power cut out momentarily again.

All in all it seems that if I can downshift to 5th as soon as I hear the noise and then shift back into 6th I won't have the power loss. If I wait awhile after I start hearing the exhaust noise, whether I down shift or not, I will eventually lose power momentarily.

Any help would be greatly appreciated. My only thought at this time is it may be a faulty CAM position sensor or I need to have my ECU tuned. This did seem to just start happening after I put a new cat back exhaust system on from fast intentions. Not sure why the exhaust would cause these issues though.


2009 370z Nismo 6MT 75k miles.

Are any DTCs being thrown?

Nothing has indicated on the dash that it has thrown a code, so haven't tried going to Autozone yet to hook up an OBD-II scanner to it.

One would think that a sudden loss of power would turn on at least one dash light but I have a friend with a similar problem (his will die for a few seconds and then recover) and he's not getting a dash light either. We'll be hooking up an OBD scanner to check for DTCs.

Just a thought: have you checked the fuel pump? You may be losing fuel every now and then.

I have not looked at the fuel pump, but it is on my list of things to check. I was also going to check all ground wires once I find the wiring schematic in the service manual.

Scanned friend's car (1999 Buick Lesabre) and came up with P0336 - Crankshaft Position Sensor A Circuit. Also had P0301 (Cyl 1 Misfire) yet no idiot lights.

Well that makes me feel better about thinking it is the CMPS. I'm going to scan mine once I get off work. I will let you know if anything comes up.

Everything you mention seemed to happen after installing your CBE. This would be too much of a coincidence for me to ignore. I would crawl back underneath and make sure that all of the bolts are tight and that none of the O2 sensor wires have been damaged. However, if it were an O2 going bad, one would think a CEL would be thrown. Yes, keep us posted what you find is causing this...

Hooked up an OBDII scanner over the weekend and found no codes.
I had another anomaly happen though. Both my VDC off light and VDC "on" light came on at the same time. Pushing the button to turn it off and on didn't do anything. It took turning the car off and on to clear the lights.

Check brake fluid level. When it dips below the minimum those lights will kick on. I believe it somehow cuts power as well.

Check your speed sensor. Make sure they arnt loose.

cats