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LOW BUDGET P1345, P0300 Troubleshooting steps

Old January 9th, 2017, 1:00 PM
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Default LOW BUDGET P1345, P0300 Troubleshooting steps

1998 Silverado Z71, K1500, 5.7 w/AC, 143K miles, Rough Country Front Leveling Kit


After seeing antifreeze dripping from the flywheel area under the truck, I pulled the engine to view the two freeze plugs behind the bell housing after reading in a forum that they could shift or rot out - they were pristine and it turns out the back of the intake was leaking THAT BAD. I'm kind of glad I pulled the engine, because doing the intake gasket with the engine out gave me all kinds of room and let me take everything apart and clean it before reassembly.


History of the truck:
Fuel Pump replaced with AC Delco. (Came out one day to go home, turned key, no prime pump sound - fuse good, relay good - pump bad. Tank looked REMARKABLE inside, clean, no water-no crud)
Intake gasket (while engine in truck) - FAIL
Intake gasket (while engine out of truck) - PASS! (with engine out, I also replaced the oil pan gasket, oil filter housing gasket, corroded power steering hose and oil lines to the oil cooler)


I knew that when I put the truck back together and tried to start it, that I was 1 tooth off with the distributor - but it ran decent and I didn't care at that point (late at night, kids gotta eat and I have to get to work)....instant P1345.


I cleared it finally - I learned that the distributor housing has the "6" and "8" (number of cylinders in your engine, look online for pics) cast into it (where the distributor cap meets the distributor housing to cover the rotor), and for me, the rotor contact should be pointing DIRECTLY at the "8" (along with the Crank pulley line is matched up to the timing mark lump on the timing chain cover) when at TDC. This got rid of my P1345 after 3 trips, 6 miles long, shutting down the engine and clearing the code each time I started and ended the trip if it was there - it has not yet returned. I was prepared to re-gap my spark plugs from .60" to .50" or less if this wouldn't have fixed it - but it looks good now. I will re gap the plugs if the P1345 code returns; but so far, one week later, its running great.


Next was the new P0300 code.


I was at 1/8 of a tank of fuel, so I drained what was in there and refueled with mid-grade (fuel didn't separate or look bad - huh?. (I also took some black plastic split wire loom tubing and used it on the coil-to-distributor wire, in case it was arching to the huge wire harness bracket on the passenger side of the engine behind the coil mount-the coil wire looked good, no chaffs, splits or gouges).... the P0300 is now gone. I think the fuel change fixed it; but I left the split tubing on the coil wire anyway - If it bothers me enough to know what actually caused it, I'll pull the tubing off to see if the P0300 returns, but it isn't hurting anything and the code is gone.


The troubleshooting list I respect for these codes are: (WHILE USING MY ACTRON U SCAN OBD II SCAN TOOL)


Corroded/Worn Distributor Cap/Rotor (P1345)
Associated Bad/Loose Wiring
Loose Distributor Hold Down (P1345)
Timing is off/needs set (P1345)
Worn Distributor Gear (P1345)
Bad Plug Wires (P0300)
Bad Plugs (with associated cylinder codes or too wide gap, set to .50") (P0300)
Bad Fuel (P0300)
Clogged/Bad Fuel Injector Spider (P0300)
Bad Crank or Cam Shaft Sensor (P1345)
Bad Sensor Wiring (P1345)
Slipped, Worn or Loose Timing Chain (P0300)
Bad Intake Gasket (with associated coolant in oil or fluid leaks or air leak test) (P1345)


I'm not saying that you will only have these codes, if something more involved is wrong-you'll probably have more codes to help diagnose the problem or point you in a specific direction,...P0300 is kind of vague....


Every single time that I've had to fix something on this truck-I had to ask myself "What's the last thing that I touched or that happened before this gripe?" and it all made sense.


Next up, the Air Bag Light. I think the sensor under the driver's seat is corroded from wet carpet due to a leaky passenger 3rd door window... we'll see what happens with that.
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