1992 Nissan Truck emgine misfire when warm/hot

1992 NISSAN TRUCK
255,000 MILES • 4 CYL • 2WD • MANUAL
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92NISSAND21
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When first starting, and for the first minute or so of idling, the engine is smooth. After that, it develops a miss and it will misfire about every 2-5 seconds at idle. Engine also has a pretty substantial miss when lightly on the throttle or when coasting.

I checked spark plug gapping and the wires are in good shape. I recently replaced many of the vacuum lines, but will test with vacuum pump. I also checked the amount of play in the EGR valve when the engine was off and the diaphragm moves fairly easily.

What should I do next?
Apr 13, 2010 at 8:56 AM
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OBXAUTOMEDIC
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Hello,

Ok you checked the plugs. What about the Cap and Rotor.

Remove the cap look inside at the electrodes if they look like they are corroded replace cap and rotor.

Post findings.....


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Apr 14, 2010 at 4:55 PM
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92NISSAND21
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cap and rotor look good (no substantial wear/no cracks), except: I recently replaced the timing chain and when I put the oil pump and distributor back on, the rotor wasn't pointing exactly at #1 when at TDC. Rotor was past #1, and I initially didn't think too much of it. I just recently retarded the distributor and the engine misfires much less and with less intensity, however now the idle is higher than it should be and it doesn't kick down in rpms like it should.

Do you think if I remove and reinstall the oil pump and distributor, and get the rotor to face closer to#1 at TDC, do you think that should do it?
Apr 15, 2010 at 6:59 AM
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OBXAUTOMEDIC
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I don't think you would need to remove the Oil Pump. But yes getting the distributor set in right would most likely fix the misfire.


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Apr 15, 2010 at 7:28 PM