I have a 1999 Nissan Pathfinder 3.3L that will start and run great when engine is started cold or hot however if the engine is allowed to partially cool luke warm engine it will struggle to start and most times will not start until it is allowed to cool completely. if I unplug the coolant temp sensor it will start and once it is started and idles smoothly I plug it back in and it usually runs ok. My commute to work is 50 miles and I start it cold in the morning and again in the afternoon and most times I don't have a problem a few times it has stalled in stop and go traffic and runs a little rough but not very often. My problem is on the weekends when I run arrands walmart, lowes when I get back to my car it won't start and 1/2 the time when it does it runs rough. I have scanned it many times hoping for a code to point me in the right direction put the only code is the coolant temp sensor from when I unplugged it. Now what I have done through this ordeal is a new distributer, plugs, wires, cap, rotor, and coolant temp sensor. I would really like to know how the coolant temp sensor reading warm could affect it in this way. time line running rough tune up: Plugs, Wires, Cap, Rotor runs better but then the luck warm no start first occurs replaced the distributer after learning of there many problems no change beating my head against a wall many times unplugged the coolant temp sensor and it started victory I thought replaced the coolant temp sensor and still no change d**n it partial victory I can at least start it now unplugging the coolant temp sensor and I'm not getting stranded any more. more beating my head against a wall current day asking for help
Please don't hurt more walls! Just kidding..what a problem. If you have the correct sensor installed and it is working correctly (check with multimeter for change in resistance when cold, warm, hot) then the signal getting to the computer must be getting scrambled in some way. Check the wire connection where you clip it onto the sensor. Use a multi meter and check for continuity there and back further along the wire.
if you can't trace the wire all the way to the computer, you may have to do a bodge job..rig a wire into the cab with an on off switch.
Only to be used when the engine is warm..flick switch to off, start truck, flick switch back to reengage sensor.......
think of it as an unusual theft deterrent !
SOURCE: 1995 Alitma ran rough and stalled
Its just fouled some plugs again. Need an overhaul. If you just put a valve job on it it will just put more stress on the rings and will need it anyway. Not much you can do except change plugs all the time!
God Bless Greg
SOURCE: MY 220K MILE 1997 NISSA
A throttle positioning sensor or idle sensor can cause these problems, low fuel pressure can cause these problems also low fuel pressure can be caused by a faulty fuel pressure regulator.
SOURCE: 92 nissan 240sx wont run
a weak coil could cause that problem
could also be an issue with the ECM / PCM
low fuel pressure caused by a weak fuel pump, clogged filter or dirty injector(s)
if you haven't tried this already then you should. get some QUALITY fuel system cleaner / injector cleaner, and follow the directions.
hope this helps.
how bout the fuel filter and pump sounds like a fuel delivery problem
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Hi Anonymous, I'm going to put this in the comment section since it is not really an answer.
If your scanner will read data from the sensors, I would want to know what that coolant temp sensor is reading cold, warm, and hot. If for some reason the sensor is way off when the engine is warm, it could be making the injectors very lean or very rich. Could be a wiring problem too.
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