well its been a good while since ive been active on here i had totalled my neon described in my sig. but now i finally have another one again. its a 97 2 door 5 speed sport but it is sohc unfortunally.

any way the neon runs perfect on all cylinders but about after 15 minutes of driving it starts to misfire. ive swapped plugs wires and coil packs from my spare dohc motor and it continues to do the exact same thing. if i vary the throttle just right at a certain rpm it seems to run good at that steady throttle. however then it'll decide to run on all 4 and be good then the next minute itll slightly misfire then itll be straight up 3 cylinders. and sometimes i swear it'll be on 2 cylinders cuz it wont have any response to the throttle it gets so bad i have to pull over cuz it wont have enough to even make it down the road. im startin to think its beyond a simple fix like i need to get a new computer in which case ill just swap motors. my friend suggested runnin a compression test but when i first start it its very strong hell i can catch 3rd gear with this new clutch. but after a while it'll start messin up. what could it be?

 

and another thing sometimes whenever i start it 4 the first time it will roll over forever and not even try to start then ill turn the key back and do it again and it'll start perfectly. but i just went out there and started it after 3 hours of sitting and it started right up but it was misfiring it didnt run perfectly like it usually does when its cold. to me it sound like a weak coil pack but ive tried the one from my dohc and i kno that one worked perfectly. i did take it to autozone and they ran their code reader on it and i ot cylinder 4 misfire, IAT sonsor voltage high and something about the MAP sensor so i replaced all of them with ones from the junkyard cuz the dohc wasn't the same and no changes at all...

 

I would check the fuel pump. Usually when engines take awhile to start cold, it means that the fuel pump is draining back to the tank when it is shut off. A weak pump could also cause miss firing issues. Get or borrow a fuel pressure gauge and see what it is cold cranking and running. I am not a neon knowledgeable person so I have no idea what the pressure should be but a quick search should reveal that.

 

Fuel pressure should be 49psi.

 

well i ran a pressure test and i was at a steady 4psi on the fuel rail while it was running by spraying carb cleaner directly into the tb. i dropped the gas tank and pulled the pump assembly out and pulled out what i thought was the fuel filter. it was very clogged. when i looked up fuel filters online i saw they had in the picture of a fuel accumulator the thing mounted next to the tank on the passenger side. is this actually the filter? then what is the thing that was clipped to the outside of the pump assembly? i was just plannin on replacin the filter and hopefully that would fix it since it was so clogged. should i replace the pump too? either way i think imma just try replacin the filter and seein if that'll work and fix the problem. but which part is actually the filter? and should i replace both the accumulator and the filter?f

 

also do you think the pump is bad too or could that thing thats clogged on top (whatever that is) be whats bringin me down to 4 psi.

 

The fuel filter/pressure regulator is mounted on the mounting flange of the fuel pump on the external side and looks like this...

 

ok great thanks i just pulled the whole assembly from the junkyard but my sending unit must be messed up because it doesnt always work and sometimes it reads perfectly and sometimes it just goes up a little bit.

but anyway i simply replaced the fuel pump relay and all was good as far as fuel goes. but my misfire is still there. i have a misfire on cylinder 1 ive swapped my dohc and sohc coil pack back and forth several times. ive swapped around all wires i have and changed the plugs from used bosch the ones with two tips to my used dohc plugs: ngk iridiums. still the same thing. what else could it be for the misfire. ive checked resistance on injectors, compression test fuel pressure test and put noid lights on the injector plugs and everything passes. i was thinkin either the cam position sensor since it controlls ignition but wouldnt i have a code 4 that if its bad? what else should i do?

 

Have you tried swapping injectors?

 

no i havent tried swappin the injectors becuase the dohc injectors are longer. but i checked resistance on them and its at 13 ohms all the way across and i also checked the plugs and they are pulsing power to them but i will go and get some injectors from the junkyard and try them to see if mine were clogged