My engine misses and backfires terribly under a part throttle load and I cant figure out what the heck is going on.It doesnt miss when I five it wide open throttle though.Just when I leave a light or try to maintain speed or accelerate mildly.It shakes the truck and rattles the dash it misses so hard.
It also backfires under the hood,or in the exhaust.
plugs are good. wires are good. no codes other than an occaisional EVAP leak code(0443)
not really sure where to look first and dont wanna keep throwing parts and money at it either.
Any help, ideas?
Thanks

 

no ideas?
forgot to add that it pings really bad when this happens

 

well it could be electrical. plug not firing, bad wire, rotor, or cap or coil.
or it could be fuel, low pressure, clogged filter, rusted up rail, clogged up injector.
mis-wired plug wires, sensors, the list goes on.
water in gas.

with nothing to go on other than time and money, sometimes you just have to guess and swap parts, and keep the old ones for the next time you have to swap parts.

 

Pull the plugs and see if any are heavily corroded. if so run a compression check and or leakdown test. If any cylinder is low, odds are its a burnt valve.

 

^^ good idea. start with the absolute worst case, and come down from there.
i wasn't aware that pinging was associated with valve or head problems, but who knows.

also since he doesn't tell us what year it is, we'll just guess that its obd2 since he's got a 0443. i'm surprised that if its really running like crap that he's not getting misfire codes 301-308 or blinking CEL or something.