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Showing results for tags 'spark plug'.
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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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Short version: 2018 silverado 2500 6.0 intermittently misfiring on bank 1. Holes 1/3/5/7. Changed 02 sensors, plugs. coils, catalytic converters, spark plugs. Once the truck is above 1300rpm or so, it doesn't misfire at all. Cannot seem to find any relation between whether ambient temperature is hot or cold or when engine temperature is hot or cold. Long version: Hey Y'all, I bought a used 2018 Silverado 2500 with a 6.0 L96 "G" about a month ago. Used from a sales lot. 160km (100,000 miles.) After driving about 200 highway miles or so, I was at a red light, and it was idling (burbling and chugging) a little weird. When I went to leave the red light, the engine was a bit hesitant, but once above 1200rpm or so, it drove fine. Over the next few days, It did the same thing intermittently and ended up throwing some codes: P0420: Catalyst system low efficiency P0137 H02S Circuit Low voltage sensor 2 P2097 Post catalyst fuel trim system high limit bank 1 P2099 Post catalyst fuel trim system high limit bank 2 P0300 random/multiple misfire. However, once rolling, it performs fine with no drama. The dealer gave me a 2 year unlimited mileage powertrain warranty through a 3rd party company. The warranty company does not pay for diagnostic work, just part changing and part cost. In order to get this warranty, I agreed to do oil change/spark plugs/air filter. For peace of mind, I ordered new 02 sensors (2 up 2 down) 8 new plugs (stock replacements) ignition coils and ignition wires. Once the parts came in, I got underneath and changed the 02 sensors. It looks like they had been changed at some point because they were aftermarket sensors. I started the truck up and cleared the codes. It ran fine for 10 minutes. I had my fiancée come out to back the truck out of the garage (I was filthy) and as soon as it went in reverse, it started idling like dog sh** and stalled out. I started it up again and we coerced it out of the garage. At this point I was tired and cranky (up for 24 hours with 12 hours of work in there.) I was in no mood to carry on with working on it. I took it to a shop and we plugged the Gucci Snap on scanner into the truck. It showed it was misfiring on 1/3/5/7. All bank 1. Bank 2 was fine. The mechanic/shop owner and I decided to have the coils/plugs/wires changed and see what happens. He called me later that evening and said the truck was running like a top. He had his datalogger on and it hadn't recorded a single misfire. I went to the shop and saw the truck had been running for about 40 minutes without recording a misfire. Drove it 10 minutes to a friend's house and had dinner. It worked fine. No idle or low RPM acceleration issues. When I left his house, I let the truck run for a minute and it started repeating it's prior behaviors. Did some studying at youtube university. Added a 2nd ground off of the coil harness to ensure it was grounding properly. No change. Cleaned MAF and throttle body, no change. Called some friends that are smarter than me. We concluded it may be the catalytic converter. While the truck wasn't short on any power.. It was a company truck (seemingly well maintained) that likely idled a lot. There are nearly 7000 hours on the truck. Not sure if that's high hours for the mileage. Took it to an exhaust shop and asked them to determine if the cat was pooched. They called me back and said it was. I did not ask how they determined this. Ordered a new set of Magnaflow cats (and a muffler for fun sounds.) Had them installed yesterday. Picked them up from the shop and the truck ran great. Today, it started doing the Harlem shake again. I'm guessing after this... It's got to be a wiring issue? Chafing somewhere? What makes me have a hard time believing it's electrical is that it is strictly RPM related. Idle to about 1300/1400 rpm. And intermittent. Once I'm cruising it's fine. If I am at a lower speed and the trans is in a gear where the RPM is low... it will (very seldom) struggle a little to build RPM. I've been using the gear selector a lot to keep the RPM's above 1400. I cannot seem to find a correlation between when the engine is hot/cold etc. If any of you have some insight, it would be greatly appreciated. This weekend a friend and I are going to hookup datalogger to check fuel trims, and also watch for misfires while wiggling harnesses and such. Have a great day! I'm about to lose my mind. This has been a slow process
