My daughter is having an issue with her Sentra. As it started getting colder out when she started it, it would rev up and down quickly for about 10 to 15 seconds before it evened out and ran to warm up. This went on for about a week and then the other night, she went to start it and it would crank like it wanted to start but would not. By the time I arrived where she worked she had gotten it started once but shut it off because it smelled bad like gas. I started it back up and it did smell bad (exhaust/gas) for a little bit but again evened out and she was able to drive it home. The next day it would not start again. I tried as well, no luck. No check engine light was on but I decided to scan for codes anyways, had 2 pending, P0102 and P0113. I then changed the MAF sensor, the codes went away but it still does not start. I did check the oil, and it was not showing on the dipstick so I added 2 quarts and it shows back to normal levels. I tried resetting the ECU with the key on/gas pedal holding thing and I think I may have gotten somewhere but I don't think there was enough juice left in the battery to turn it over. I disconnected the negative and am letting it sit for 24 hours until I get done with work tomorrow and can go jump it and try to start it. My question is, has anyone had this issue? Is there anything I should look for in case resetting the ECU does nothing?

Thanks in advance!

Update - Reconnected the battery and charged it up, still no start. The fuses are good and I can hear the fuel pump kick in, I'm thinking maybe the Crank Position Sensor? If anyone has any thoughts I would really appreciate it.

Thanks!

Cam is more likely than crank on an MR engine, and a lot easier to try out. Either one can cause a no-start with no codes if it's lying to the ECM and not flatlined. Try pulling the cam sensor and see if it starts after a long crank. If not, plug it back in and disconnect the crank and see if that starts it. If neither one works then try turning the cam sensor 90 degrees in the bore with the retainer screw removed. If none of that works, it's unlikely your problem is the sensors (although it's still remotely possible they're both bad). One quick test for a bad crank sensor is whether your scanner gets a steady RPM signal while cranking, if the reading is zero or bouncing all over then chances are the sensor is shot.

The original codes you had indicate a problem with the ground wire or ground connection to the MAF (the IAT and MAF don't share power but they do share ground). However, they could have occurred if you pulled the MAF loose with the key on, so they may not mean anything.

VStar650CL wrote: ↑

Fri Dec 16, 2022 7:58 pm

Cam is more likely than crank on an MR engine, and a lot easier to try out. Either one can cause a no-start with no codes if it's lying to the ECM and not flatlined. Try pulling the cam sensor and see if it starts after a long crank. If not, plug it back in and disconnect the crank and see if that starts it. If neither one works then try turning the cam sensor 90 degrees in the bore with the retainer screw removed. If none of that works, it's unlikely your problem is the sensors (although it's still remotely possible they're both bad). One quick test for a bad crank sensor is whether your scanner gets a steady RPM signal while cranking, if the reading is zero or bouncing all over then chances are the sensor is shot.

The original codes you had indicate a problem with the ground wire or ground connection to the MAF (the IAT and MAF don't share power but they do share ground). However, they could have occurred if you pulled the MAF loose with the key on, so they may not mean anything.

Thanks for the reply! I will try what you suggest here, hoping it's not a ground/wiring issue... but we will see. What I do know is it started not starting the day after she took it through the car wash... Not sure if that is just coincidence but it's got me thinking maybe something got knocked loose or something.