p0300 and p0141

97 blazer misses at about 2000 rpm only whem damp or wet out. p0300 code pulled multiply times and an occassional p0141. new cap, rotor, plugs wires last spring. problem is only noticable during first mile of driving ac plats, bosch wires, duralast gold brass insert cap and rotor 130,000 miles no visable sparks at night or when sprayed w water. any thoughts

P0300 is "random/multiple misfire detected", most commonly set by secondary ignition faults. AC platinums are the best spark plugs for the 4.3L. Bosch wires should be ok. Spraying water is a good test for wires, plugs, and external distributor cap, but you can't see what's going on inside the distributor cap. My advice...lose the duralast stuff. Go with AC Delco and make sure the vents in the distributor base are clear.

P0141 is "O2 sensor heater circuit malfunction (bank 1 sensor 2)". More than likely not related to the P0300. Could be wiring for the sensor or the sensor itself is faulty.

all fixed and it never ran so good. i used a car chip module and found p0300 codes on every trip and an occasional p0141 oxygen sensor code. went to a friend who is an ace private mechanic who has a good up to date "snap on" code reader. he scanned the computer and found all sensors ok except for the sensor in the distributor. when he pulled the cap it was arced all over the place. he has never seen on so bad. replaced the dist, cap, rotor and plugs wow what a difference. a year or so ago i remember a post about a 4.3 gm crate engine being installed by a chevy dealer where the dist was clocked wrong. they had to drill the mouning plate to allow the distributor to be rotated so the engine would fire. the first distributor my mechanic put in my engine was clocked wrong. the second matched the original. he also found two other codes, one for the abs brakes and the other for the fuel guage. he fixed both of them in the computer and all is well. the actron and the car chip did not detect the two other codes. as of today and another 50 or so miles no codes and no problems.

i just found the link to the post i mentioned above about slottingthe dist. hod down or a miss clocked distr. i hope this link works http://www.automotiveforums.com/vbulletin/showthread.php?t=577484&highlight=distributor+hold+down


it is from july 2006