Hi I have a 2001 Nissan Xterra with trouble staring when cold . I've replaced the fuel pump fuel sending unit fuel filter fuel relay and finally fuel pressure regulator . After I replaced the regulator the car is a lot easier to turn on then before still hard to start when engine is cold. I live in Texas so it doesn't get real cold . There's quite a bit of stuff I've already replaced I am getting spark n fuel I don't know what else if could be . I've found a couple vacuum hose leaks replaced and runs a lot better when it finally starts . Any help would be appreciated. Thank you for your time .
My car has 225265 miles.
My car has an automatic transmission.
Make sure your battery and starter are in good enough condition to turn the engine over at high enough RPM's to start properly in low temperature conditions. Due to the relatively high miles, I would first check and confirm cylinder pressures, via compression test, to see what your starting conditions are.
Faulty components in the exhaust gas recirculation system and any idle speed air controls (if equipped; try starting car when cold with accelerator pedal completely depressed and see if that makes any difference) would be relevant to look at.
Other possible faults to check are the condition of the distributor, cap and rotor, [plugs],(https://www.yourmechanic.com/services/spark-plugs-replacement) and wires, engine timing which could be off (also timing belt, if old, could have slipped a tooth or two). Due to the age and mileage, the fuel injectors could even be partially plugged. Keep in mind, you may very well not have a single cause of this condition but rather there is a combination of degraded components that together cause hard starting during cold weather which is generally the most difficult time to start an engine in any event. If you need help with a diagnosis, a certified professional from YourMechanic can come to your car's location to inspect the starting problem and guide you through repairs.
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