CEL on, random misfire, mechanic suggested plugs and wires. 160K on car, found oil in spark plug tubes so I replaced valve cover gaskets and seals, plugs, wires, cap and rotor. Still CEL comes on P0300. Replaced distributor with Cardone rebuild, Advanced Auto part# 31-49600, still getting P0300- only now instead of having to drive 80 to 100 miles before code comes up, in will come up in less than 30 miles. I still have the core.

Q: What next? I am at a loss.

Thanks in advance (no pun intended)
Chuck

 

A code P0300 may mean that one or more of the following has happened:

• Faulty spark plugs or wires
• Faulty coil (pack)
• Faulty oxygen sensor(s)
• Faulty fuel injector(s)
• Burned exhaust valve
• Faulty catalytic converter(s)
• Stuck/blocked EGR valve / passages
• Faulty camshaft position sensor
• Defective computer

I would just start running though these and see what happens

Here is the link for the page I got it from. Best of Luck

OBD-II Trouble Code: P0300 Random/Multiple Cylinder Misfire Detected

 

Appreciate the come back, it gives me some more things to check.

Chuck

 

What's the vacuum reading at idle? AND how did the dist come eqipped, did you have to use the old coil?

 

Steady 16 in.Hg.. Used a MityVac for reading.

Update: Had a friend who had the high dollar scan tool. Code hit at 14 mph and occurred at 2 rpm (yes 2 rpm). Ran the scanner while idling and found the EGR voltage high, between 2-6+; hit it with break parts clean and the voltage dropped into high negative numbers- engine stumbled bad. My friend believed the EGR valve was slow to close at times throwing the P0300 code. Replaced EGR valve and drove 80+ miles and had it inspected. The car had gone through 2 of 4 test cycles so it was able to be passed.

Dang lite came back on before I got home. At least the inspection is done, but I'll have to pull the codes and see whats up now. Auto never really ran bad nor had my wife noticed when the engine was falling on its face.

Thanks,
Chuck

 

Dist came with coil- everything but cap.

Chuck

 

Just a note to pull this thread to a close; pulled code and it came up p0300 again. Reset and CEL came back on after about 80 miles. Lite went out after another 70 miles and has been out now for 5 days.

Thanks for the help.
Chuck