My 1994 nisan maxima was running fine when it was parked 2 yrs ago it now acts like it has a miss I changed plugs and wires fresh gas with fuel cleaner still missing what else could be wrong
If the car has sat parked for 2 years with fuel left in the fuel rail and gas tank, be sure the fuel tank is thoroughly emptied BEFORE you add fresh gas. The injectors are probably plugged with varnish and gunk from the fuel sitting in them for so long. Gas has a shelf life of 6 months, at most, and even less in sub-optimal conditions like an air filled (partially empty) gas tank. All of the fuel injectors should be removed from the fuel rail and sent to a reputable lab for ultrasonic cleaning, flow testing, and replacement of the internal injector filter baskets which are incredibly fine but are now plugged with varnish. A lab I have personally used and recommend is Mr. Injector. On the car "attempts" at cleaning fuel injectors, and "aftermarket" cleaners are a waste of your time and money and are not the technically appropriate way to both clean injectors and, most importantly in your circumstance, thence be able to rule the injectors in or out as a cause of the misfiring. Varnish and gum from expired gasoline could have also plugged up the fuel pump and fuel filter. The fuel filter should be changed for sure. You can defer action on the pump until you clean the injectors because the pump may still work well enough (it can be tested for output and pressure, of course). Just be sure you install a new fuel filter. If cleaning the injectors does not resolve the issue, request a misfire diagnostic and the responding mechanic will scope the engine and look at the secondary firing patterns to determine which cylinder(s) the malfunction is in. I would recommend that now BUT given the known issue that gas sat in the car for 2 years, you have to clean the injectors anyway and replace the fuel filter so try the obvious potential solution first. If you desire that the injectors be removed and mailed off to the lab with the assistance of a certified mechanic, by all means request fuel injector service and the mechanic can handle that for you. Note that replacement of injectors back into the fuel rail is tricky...you have to insert them just right, not tearing the o-ring seal or you will have leaks. Please let us know how we can best assist you in restoring the car to good running condition.
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