rolling into work downhill today, coasting in 3rd foot off the gas. barely put my foot on the accelerator to feed a bit of gas while coasting and the engine made an almost 2-step sputter, like my other tuned g35 on its 2 step map, and popped really loud (this car isnt tuned). nuetral’d it and as soon as i touched the gas again lost power before coming to a stop. luckily rolled into the parking lot and made it but wonering where to start with this? no codes at all, no flakes in the oil, idle relearn does nothing. slight oil leak but possibly from my lower pan, any ideas?
update: started twice on my break, only starts when its cold and idles for about 5-10 secs before dieing. sounds happy until it dies. threw in a gallon of gas no difference still. video below

 

https://youtube.com/shorts/fx8LNG7DmFU?feature=share

 

Nice healthy crank, however your tachometer isn't moving when cranking so I suspect your crank position sensor died.

I bet if you scan for codes it's throwing P0335 CKP crank sensor. If so make sure to only replace it with a HITACHI or an OEM Nissan sensor (Hitachi was the OEM manufacturer for that sensor). Don't use aftermarket ones, these computers don't play nice with aftermarket sensors.

 

i have no codes, have been constantly scanning for them but no luck. i believe its fuel or spark related since it isnt throwing any codes. recently upgraded to an aem 340 pump no tune yet but it has been running great

 

Crank the engine for a good solid "one one thousand two one thousand three one thousand" count and watch the tachometer. If it doesn't move then the ECM isn't receiving crank position sensor signal.

It isn't moving in your video but those were also really short engine cranks. Make sure to only use a Hitachi or OEM Nissan sensor if you replace it. These cars don't play nice with aftermarket sensors, Hitachi was the OEM manufacturer for it.

 

i have two G35’s, other one no issues. my other g does not move the rpm needle at all until it fully fires and attempts to catch idle. just confirmed this morning

but i will jack up the car and take a look at my crank sensor later today with an ohm meter if i can for sure. probably dismount it and make sure its not covered in debris or something

 

seems to be an intermittent TB, checked my obd and it had 0.0 throttle position so i swapped it out with one i had in my junk pile just to test. fired right up and idled for about 20 minutes and did a relearn as many times as i asked. great! but when i reinstall the one i was running when i had the issue, clear codes, and start up it fired right up again and has been holding an idle for about 20-30 mins. does the idle relearn no problem, revs, no codes still. seems normal again, should i invest in a new TB? all i did was polish it this past weekend and i was extremely careful to only polish metal bits that were visible, far from the electrical components covered by plastic.

moving this month just need it to make it to my new place about 25 minutes away appreciate the advice

 

Sounds like maybe the harness didn't fully engage on the TB after you installed it after the polish.

EDIT: Or possibly a damaged wire on the harness, and now that you've moved it around a little it's making contact again. Try wiggling the harness wires around while it's running and see if it stalls or throws a code.