1997 Olds Bravada 170,000 miles.
Misfiring at idle something awful, almost to the point it shuts off. When revved above 2000 rpm’s it smoothes out.
For a few weeks up to the night this started the truck had been running warm (3/4 mark on gauge) but it has been 100 degrees during the day, This night the temp was fine and I was heading down the highway around 78. I was going up a hill and the truck downshifted to maintain my speed and at that point something happened. Not sure what (I did not hear anything because I had the radio up) but I could feel loss of power and the truck seemed like it was straining to get up the hill. Seconds later check engine light came on. I pulled into the next gas station and it was idling something awful. So I shut it down and checked all fluids and vacuum lines everything seemed ok. I had someone check to see if I was blowing smoke and he said it was white when I revved it up. So I re-checked the oil again and I saw bubbles which indicated water in the oil. I figured I had a blown head gasket. So I towed it back to a friend’s house who is a mechanic. I rechecked the oil and no bubbles or signs of water! Water in radiator full oil was full but not over. He checked the computer and it gave a P305 code indicating the number 5 was misfiring after checking the plug it was bad spark plug, woohoo that’s cheaper than a head gasket! So I replaced all plugs and fired it up and it had the same problem. So I rechecked the codes and it gave me a P300 which indicated multiple misfires. So I replaced all the plug wires and the distributer cap and rotor button. During this process We noticed where you screw the cap into the distributor the plastic screw holes one was broken so we could not tighten the cap all the way down we did test the truck at this point because the cap was tight enough to test but not a permanent fix! It seemed to idle fine so we were excited! I went and got a new distributor and put it back together well wouldn’t ya know as soon as we fired it up we had the same problem as in the beginning. When putting the distributer back in we lined up the TDC on the Crankshaft per the manual and checked the #1 for TDC and then the rotor was facing I would say the 8 o’clock position. We rechecked the codes now I am getting a P1345 code.
Any suggestions on where to go from here??