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Showing results for tags 'P0303'.
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This morning while heading to work I was accelerating onto the highway and at about 50mph I feel/hear a POP in front of me and several lights come on. Engine is misfiring and running rough. SES light, service parking brake light, traction control off light turn on and the transmission is shifting hard. I coast off the on ramp, turn it off, and look it over. No rod sticking through the block or pan. No sign of a head gasket. Seems to be correct oil pressure when running. F&$@%##}#%}} I just paid it off. 117,****** miles. Oil changed every 5,000 with synthetic and mostly highway miles. Call out of work and limp it home. I have an ancient scan tool and it shows P0303 cylinder 3 misfire. Reset the codes. Swap the coil to cylinder 1 and put a new ACDelco plug and wire on cylinder 3. Was planning on doing plugs and wires this coming weekend ironically. Runs better but not right. Lights come back on. Now the scan tool shows P0303 and P0500 which is the vehicle speed sensor. WTH? It wasn’t moving this time. Where’d the P0500 code come from? Going to try putting a new coil on 3 and putting the cylinder 1 pack back on 1. Would love some thoughts and hell, prayers.
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Long Story. 1980 and a few months before standing on yellow footprints, in high school auto shop class, Mr. Collins saw I was having difficulty mating a transmission to an engine. Called me out from under the wagon, reached into his pocket and pulled out 30 cents and told me to get a soda. Mr. C was a quiet man and often taught us without saying a word. I complied, bought a soda added Cheetos, walked to the back over-viewing the canal. Finished, crawled back under the problem and withing 30 seconds the bits magically lined up and I moved on with the build. He knew I needed a break before I did. Fast forward eight years, snapping in a new crew maintaining F-18's, one of my Marines having difficulty installing a fuel pump on a gearbox, so I reached into my pocket pulled 50 cents and told him to get a soda, he stared at the coins, looked bewildered, however me being senior complied. Coming back from the break, told him how to position his body and what Zen like hand force would pop it into place without buggering the o-ring. When you can, pass what you learn to the replacements. Late 2015, returning from my cave analysis of gas vs diesel chose the 6.0 2500HD for my business installing pack lines in processing plants. Using a Truck Camper and 20 foot equipment trailer, I stay on-site till the job and training is done. This means 98% of this trucks' life is at payload, pulling 10k pounds, making money every time I get in it. Current mileage 190,090. Until 185K my rig serve faithfully, except for a craced brake line connection near the differential at 114K miles in Michigan. Did a combat repair late Saturday afternoon before the town shut down and every auto parts store didn't have the firing solution...which came from all places, a muffler shop...then drove to KY for a Monday meeting to close on another pack line...but that's another story. Starting hearing a tick on start up, but after warm up it would go away. Inspected exhaust manifolds and noted driver side rear bolt head was gone, carbon was on the head and needing the truck for work, opted for the Kral manifold clamp. Drove another 5K on the the truck, but no luck stopping the tick...knew the easy way was over and next step was pulling the exhaust manifold. Also starting getting a intermittent P0306 and P0303. Removed the exhaust manifold and the warp was troubling, but I foolishly tried to file out the warp and replaced manifold gasket then reinstalled. Still ticking, the last gasp was a motor flush hoping something would magically free a lifter and all would be well. Nope, still had the tick and getting louder, knew after 39 years of not seeing the inside of a V8 valve cover, what I had to do. Now for young folks, removing valve covers may not seem a big deal, but 39 years ago vehicle maintenance didn't include ECM's, rocker rails, hydraulic roller lifters, fuel injection on cheap cars, OB code readers, variable cams /sensors, or electronic ignition. If one said, some day in the future each cylinder will have its own coil pack, that would be grounds for throwing you out of the shop. Pulled the valve cover, still no clue then proceeded the rocker rail. There it was...source of the tick...missing valve tip. Still had some key metal so maybe I could have gone another 2K miles but sometimes you get lucky and save a motor. Down that far, opted to pull both heads, replace exhaust valves springs, seals, lifters and buckets. Cam was good. Cleaned carbon off the pistons using Gunk Motor Flush and removed rubber stuff remaining on the block. On the advice of my head re-builder, replaced gaskets with AC Delco OEM. Reassembled the heads. Note rocker replacement. Purchased from Summit and had to sign a waver stating it was a performance part and must be used off road. Although its a GM part number and not aftermarket, played the click here game and received them without enviro-police showing at my door. Since the block remained in the truck, opted for ARP bolts so I didn't have to mess with angle torque near the firewall. Have to say at my age, 89 foot pounds laying horizontally, in the Superman position over the grill just about kicked my ass. Torquing clam-shell jet motor mounts was a lot easier. Less I forget...if your going to tackle this job...get the thread chaser. This was residue after cleaning with brake cleaner and blowing air into the threads Driver side Exhaust Manifold (Dorman) from NAPA went on without issues, however the passenger side (ATP) from Rock Auto was a bust. Removed from plastic, lined up to the head and missing #6 exhaust flange. Air bubble in the cast. Shipped back to Rock Auto, they refunded my coin. Pulling off the passenger manifold heat shield and showed a nice 3 inch crack. Most likely the reason for the P0306. But to be safe, replaced the coil and fuel injector. Off to NAPA for a manifold (Dorman) but again another problem. Manifold made in China, doughnut seal made in India, parts assembled in Mexico...what could go wrong? Exhaust doughnut was too small. Back to NAPA dragging the old manifold, explained problem to two hard charging ladies who knew parts. They sourced the right doughnut (Fel-Pro 61694 2007-12 - replacing 20987829). Next time I'm opting for stainless headers. Final PITA issue was brand new AC Delco 7mm PERFORMANCE wires missing a spark plug clip. Clue to the problem was written on the box. Assembled in Mexico. There's no quality control when your paying $3 and hour. Oh...back in my day Valve Covers were made in the US, now its Mexico. Explains overpriced trucks and the bi-annual 20% discount on new trucks. Refilled engine oil, noted dip stick was missing, reinstalled, bled the fuel rail and the 6.0 fired right up. Two hesitations clearing remaining air, warmed up and settle into a good smooth idle. Then heard a usual sound, not quite a tick or a tap so I shut it down. Checked the dip stick and the level was higher than normal, then realized I put 4 additional quarts into the motor. Pulled the drain plug and was horrified seeing a milky tan streaming into the oil pan. Oh crap leaking radiator fluid in the block, really thought I mucked up the head gaskets. Then smelled the oil and noted that kerosene motor flush and realized it oozed past the rings while cleaning carbon off the pistons. Two oil changes later, all is well and idles smooth. Did a forty mile loop, no leaks, radiator level steady, and oil clear. All bolts and parts accounted for except one nut. Most likely goes on the intake manifold but not worrying about it. After 39 years, I can still tally up details of a top end rebuild while working my way around a small block. I can say what we dreamed about in performance parts producing higher horsepower and torque back then, is common today. Spark plugs lasting 100K miles (mine went 130k). Rear oil seals intact, MAF sensors, billion cycle fuel injectors, plastic intake manifold, variable cam geometry, 185K on an engine working hard without failure and requiring only regular maintenance. These are great days and bless Chevy for continuing to upgrade its small block giving power to people making coin using their engineering. Also thank the internet. Anytime I had a concern or wanted more information, this site, LS1.com, Youtube was available along with ordering parts that kept overall cost below $1300. A lot lower than a diesel rebuild, but then again most likely wouldn't have lost a valve tip.
