p0300
 

i have a 96 dodge ram 1500 318, 5.2l i bought it six years ago and had problems since week one. i have taken to multiple mechanic shops and no one has fixed it. please help
i have had continues code of p0300 along with that from most resent
p0303 cyl 3 misfire
p0306 cyl 6 misfire

in past it has been before they went away for some reason but pop up once in a while
p0302 cyl 2 misfire
p0308 cyl 8 misfire

i have replaced the plugs, wires, cap, rotor, the distributor its self, fuel pump and filter, all of the fuel injectors, air filter, also replaced the air intake (keg) gasket and did a compression test on all cylinders and all cylinders checked out fine, and also changed the coil pack. and i am stuck

have to let the truck warm up for bout 3 to 6 min before it will run ok. in that time it struggles to get to a decent idal and sounds like it is going to die at bout 3 to 5 min mark then it runs ok but the misfires are still there and faintly present
any other suggestions please thank you

Wow, you sure replaced a lot of parts without properly diagnosing the problem.

First, have the spark plug wires been routed properly according to the Technical Services Bulletin?
Second, have the catalytic converted pressure tested. Too much back pressure can result in misfires, particularly on the even cylinder banks.
Third, there's a chance the heads are cracks, which is common for the stock heads on these trucks.
Fourth, remove the CKP (cam shaft sensor) that's inside the distributor housing and check for breaks or cracks. Clean the pigtail connectors, coat with di-electric grease, and reinstall.

Did you have fuel sync reset when you changed the dist?
Still the original O2 sensors?
Cleaned the throttle body?

i know that the wires are right because i did those myself, and i have not had the catalytic converter pressure tested, did not know you could do that (and can i do that myself)
i did not do anything with the fuel sync because in the haynes book it does not say anything about that, but the throttle body is cleaned and the o2 sensors i have not changed and i do not know if they are the originals, but since the o2 codes have not come on i did not think they would have anything to do with the misfire codes. i have had the o2 codes before in vehicles and they have never set off misfire codes

You'll have to take the truck to a muffler shop to have the cat pressure tested.

Neerd to take it to a shop to have the fuel sync set properly. That itself could cause misfires. Have to have a computer to set this. And Haynes is OK on some things, but iby itself, it is not enough.

Go to the FAQ/DIY section and download the service manual fgor your truck.

sorry now looking back in my records i did have the catalytic converter blown out because they thought that that was the problem. so i am not sure if i still need a pressure test on it or if it just being blown out would be good enough. it says that it is open and no blockage.

also if it helps out i forgot to mention that when started and i go to take off before the heat up it sputters and has a loss of power and sputters. when it is about to the appropriate temp it does a load pop and then works ok but with the small misfires and when i push the overdrive button so the od is off it seems so work better but not like its supposed to.
i was also told that it could possibly be the map sensor? is that a possibility or would it be acting different?

doubt MAP has anything to do with it..

i'd be putting your fuel pressure in close scrutiny..

what injectors did you use?

you may be well served by removing and cleaning your fuel rail.. little debris cause issues in those things..

edit to add:

it sounds like when the environmental controls take over you're fine.. the tables are causing an issue.. I'm real curious to see what injectors you're using, and what fuel pressure you're getting at the rail..

The catalytic converter is a critical part of the emissions system, which in turn provides critical feedback to the vehicle's computer. It would be wise for you to replace the catalytic converter as well as all of the O2 sensors. That won't fix the misfire issue, but it will have an effect on the vehicle's performance.

i can not remember what fuel injectors i put in because i did not write that down for some reason, but the fuel rail i have had cleaned out and had a cleaner put thru on the fuel system. but i have not had a fuel pressure test put on that i can remember. i thought they would have done that when they put the new fuel pump and fuel filter in.