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2002 nissan sentra car would not start . plugs were gas fowled put it on scanner showed code 128 so i changed both coolent sensors car has been fine for a month now doing same thing but no codes this time. but plugs were fowled again...

Check air temp, coolant temp and fuel pressure with scanner. Then I would check cam and crank signals as well as injector pulse. Is it excess fuel or lack of spark? Compression good? I dont see your location, was there a sudden change in temp? It is cooling off up north. When I worked for nissan years ago in Ohio we would get a rash of fouled plugs when we got the first cold snap.

coolent temp is good, cam and crank is good plugs are fowled.i can clean them with carb cleaner and it will start right up and i have noticed that it does it with less gas the spark i dont know because it has not done it too me

and compresion is good

Next step is to check mass air flow sensor and air temp sensor. I see where it also runs a baro sensor and app sensor. fuel pressure? stuck pressure regulator? Logic is to check all sensors that have an input to fuel control at cold start as well as fuel pressure. What size engine?

see if the 02 is forcing rich or a shorted tps.

already changed regulator and fuel pressure is good and it is a 1.8

o2 sensor is check good tps i dont know i have too go get car

tps check good cleaned throttle body the car runs better but would not start again today also check all sensors to do with cold start . the intake is pretty gum up