I have a 2001 Chevy Suburban 6.0 V8 with 292000 miles in which I over paid. P0174, P0171, P0300, and P0332. After driving a long distance of about 30 miles 2nd gear thumps when changing. The truck drive smooth. Do you think I should just change the spark plugs wires and fuel injectors for it not to make a thump when going into 2nd. What do you recommend thank you Scotty love channel
Do you think I should just change the spark plugs
Maybe, how old are they? You should definitely look at them
fuel injectors
maybe but there's easier things to try first.
Change your air filter. Look for vacuum leaks. Go to our FAQ for misfires.
When in doubt, find your codes on obd-codes.com and follow the instructions there.
I'm not sure what those codes are, I'm assuming they have something to do with your suggestions, but I wouldn't think if your hearing "thumps" it would be the spark plugs,wires, or fuel injectors. i would suggest clearing those codes out and see if there come back. They may be old codes with there problem resolved. To clarify, you only hear the thump or thumps(?) when shifting in or out of second gear and only happens after you've driven 30 miles?
Also, have you looked at the transmission fluid, color, smell?