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JOHN aka Eauto
JOHN aka Eauto, The Car Guy
Category: Nissan
Satisfied Customers: 16039
Experience:  ase tech over 15 years in the field uaw union member
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2002 nissan altima 2.5 liter, new engine temp sensor, new

Customer Question

2002 nissan altima 2.5 liter, new engine temp sensor, new mass air flow, new throttle body, new crank and cam position sensors, new fuel pump fresh gas, start car smokes black will not rev above 500 rpm, unplug fuel pump and it instantly starts running good until it runs out of fuel a minite or so later, plug the new pump back in, black smoke bogs down, no accell until you unplug fuel pump.
Submitted: 1 year ago.
Category: Nissan
Expert:  JOHN aka Eauto replied 1 year ago.

any codes


Customer: replied 1 year ago.
none, and everything checks out perfect on an $8000 snap on scanner, all sensors in range the only thing abnormal is the fuel trim
Expert:  JOHN aka Eauto replied 1 year ago.

Fuel trims can help you zero in on the problem, especially when there are no other trouble codes present. Knowing whether a vehicle is running too rich or too lean will help narrow down your diagnosis. Fuel trims that differ greatly from one cylinder bank to the other will also point you in the right direction. Always evaluate fuel trims at idle and at 2500 RPM.

Running too rich – High negative fuel trim corrections can be caused by MAF sensor problems, high fuel pressure, leaking fuel pressure regulator diaphragm, faulty evaporative emissions components, leaking injectors, defective O2 sensors, exhaust leaks/pinholes before the O2 sensor, coolant temp sensor problems, and base engine issues such as low compression and incorrect camshaft timing