I have a Ram 2018 Promaster city van I bought brand new with zero miles. At around 4000 miles the van's engine light turned on so I took I to the dealership and they replaced the MAP sensor. At 4500 miles one morning the van would not start to I took it to the dealership and they replaced a fuel line. When the van came back I noticed it now was running differently.. I could hear a faint spark knock detonation.. the sound of very light back firing when I would let go of the gas under load at 30mph +. I then noticed the van was low 2 quarts so I took back to the dealer to report the issue and get an oil change( synthetic 10-20w) The dealership performed an oil consumption test and after 1000 miles the van showed no sign of consuming oil, but still had detonation spark knock. The dealer said it could not hear it. I switched to super unleaded and the spark knock improved, but I have no plan to pay $10 each time for super unleaded. I noticed my tail pipe had a very thick black soot inside - i took pictures and cleaned it. I removed my air filter, it was dirty for 6k miles, I cleaned it and noticed a big improvement in how the van was running. Planning to upgrade to a K&N washable air filter in the next few days. I just pulled all 4 spark plugs to look at them. Not sure if they are okay? I plan to take it back to the dealership to check the timing and to possibly start a lemon law process though anticipate to having to fight with them and i need a car badly now. What could this be? Are my plugs good? Worth it to change them or fight to have dealer change them?
There is a video on youtube "NoSunBeach Tigershark spark knock"