Hello, I have a 2003 Ram 1500 4.7L V8 that has been throwing misfire codes. The guy I bought it from said it had a rough idle, which it does. As it idles it will start rocking and if i let it run long enough a check engine light will come on and it will say I had a misfire. During the point when the rocking becomes really bad, if i give it some gas it will go away. Also at crucial times of acceleration the motor will hesitate, and chug until i go pedal down to avoid being rear ended. The previous owner said he replaced several parts to try to fix the problem. I do not know them off of the top of my head but I will update on them tomorrow (as i am writing this at 11 Pm). Since purchasing the vehicle i have changed the spark plugs, (and they were really worn out).I had a shop smoke it when i first bought it and the only vacuum leak they found was somewhere under the motor, which they fixed and said it had no relation to my misfire. The only after market performance parts that I can account for is a K&N air intake. Could this system be the culprit behind my problem? So far when reading the codes i have had multiple randoms and one #3 misfire. Im just waiting for it to happen in the same cylinder again. (make life easier) Could all of these problems be related? Help and thoughts much appreciated. If this thread already existed I'm sorry, I'm a noob.

 

how many miles are on the motor? i would do a compression check... the heads are known to drop valve seats which i have experienced with 2 out of 3 3rd gens

 

There are 141,500. I bought it at 139 and it had the same problem. Thanks!

 

i would be leaning toward head gasket problems. last owner could have over heated the motor and put a quick "fix" with sealing products. have you check the antifreeze for anything out of the normal? most recent truck i bought had a bad headgasket and 3 dropped valve seats. it still ran but not good. drove the truck 60 miles that way home with it over heating and had to floor it to go up any kind of slope. the previous owner was sold the truck days before i bought it and the radiator was loaded with that head gasket in a bottle type crap. it worked long enough for him to buy it thinking it was all good. people that do stuff like that to sell a vehicle should be shot. its not honest.

 

Ok, thank you. I will definitely look into it. Hopefully its not all gunked up inside with that crap.