I have a 1999 Xterra, 3.3, V6. No. 4 misfire. New plugs, wires, knock sensor, distributer. will hold 90 on compression. #1. What can cause the misfire? #2. Can a lifter or injector be the cause? What would you recommend my next step be? Thank You. LaDonna Grubbs
SOURCE: will a bad knock sensor cause a misfire. car is
A Bad Knock Sensor will not cause a misfire, unless the advance is off due to a faulty Knock Sensor. The O2 Sensor will cause a random misfire.
Good luck on this repair.
SOURCE: Ok/ I have a 02 Xterra. V6 ... Auto zone scanner
Hi, you will want to fix both codes. The reason is that when the computer is not getting data from the knock sensor it defaults to a safe ignition timing that reduces performance. The misfire requires troubleshooting. First check the plug and wire. If that's good, run a compression test. If that's good, check the injector pulse (use a voltmeter set to AC, and compare voltage to other injectors--with engine running). If the pulse is good, check to see if the injector is clicking. If it isn't clicking, you know it's bad. It might also be clogged, but you have to pull the fuel rail to see if it's clogged. Please see my tip at http://www.fixya.com/cars/r6715318-causes_gasoline_engine_misfires . These are genericinstructions. If you get stuck or need specific instructions for your car, please get back to me with model, year and engine info.
SOURCE: Engine misfire and knock sensor bank 1 codes on 1999 Nissan frontier 3.3 v6
I would want to see the actual codes, but if it is one or two cylinders you could have a failing injector and it not show up as a trouble code.
If one of the injectors is failing it can have a high resistance and affect the other injectors in that circuit.
The O2 sensors and cat would not affect a power loss in one or two cylinders, and the O2 sensor codes would be present.
The knock sensor only measures vibration, so it was probably ok before you replaced it.
There is a chance the cap is shorting out internally which would be tough to see, and the optic sensor in the bottom of the distributor could be causing problems too. Some of the cylinders may not be firing when you think they are.
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