Hard to Start 2007 Altima

Tiny
GREGW123
  • MEMBER
  • 2007 NISSAN ALTIMA
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 50,000 MILES
I'm correctly having an issue with my 2007 Nissan 2.5L. When the engine is cold it is very hard to start. It seems like it is misfiring, but once it is started it runs fine. When the engine is hot it starts right back up with no issue. MIL is showing a code of P0300, which is a little generic for my troubleshooting skills.
Monday, July 25th, 2011 AT 11:18 PM

5 Replies

Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
P0300 is the code for a random misfire, with this in mind, I would first check that the coolant temp sensor is ok, as it starts ok hot this could be the issue, I would start here and let me know who it responds.
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Tuesday, July 26th, 2011 AT 7:04 AM
Tiny
GREGW123
  • MEMBER
  • 3 POSTS
Should I just ohm test the senor or try to pull live data from the ECM with my OBDII reader?
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Tuesday, July 26th, 2011 AT 12:41 PM
Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
You can do this, but you will have to get the temp scale for correct Ohm readings, I have had a look and it is not on Mitchel 1, if you can get live data this will give you a better idea as to what is happening with the entire system.
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Tuesday, July 26th, 2011 AT 12:48 PM
Tiny
GREGW123
  • MEMBER
  • 3 POSTS
Of course tonight when I got home tonight and hooked up my scanner it started right up with no problem. The temperature went from 82F before starting it all the way up to 265F after running it for awhile. Only differnce between today and yesterday is it was in the shaded garage all day. Not sure what to try next, espically if I can't recreated the symtoms. I'll let it sit in the sun tomorrow and see how it reacts. Weird. Any other parameters I should watch on the scanner if I can get it to misfire again at startup?
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Wednesday, July 27th, 2011 AT 1:13 AM
Tiny
RIVERMIKERAT
  • MECHANIC
  • 6,110 POSTS
265 degrees is pretty hot for an engine. If you have a cooling system thermometer, check the temp of the coolant in the radiator.

Check the cold start injector to make sure it's being actuated.
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Thursday, September 29th, 2011 AT 7:55 PM

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