P0300 Random Missfire

[TurboTylerT]

Hello yall, I have just had my injectors cleaned and checked which wasn't the problem. I have checked everything from ecu to timing. My fuel pressure is fine but the afr slowly goes to 16:00 after startup and then it want's to idle at 700 rpms. The plugs are not black or white but just fine. No holes in the plug wires but I am going to change the power transistor and coil pack if I have to next. Such a weird missfire because if I drive it and give it quit a bit of gas it goes away then comes back as soon as I let off. And at other times it is fine until I try to accelerate then it doesn't want to drive out of a hole.

 

[Zufelt]

Had this same problem, replaced the wires and all was gravey. My old plug wires appeared to be fine as well. Also, are the plugs gapped correctly?

 

[Total Eclipse]

Random misfires are usually either plugs or wires. Looks can sometimes be decieving!

Nate

 

[MN_Eclipze]

What kind of wires are you running? Like the other have said check plugs. Mine happened to be one leaky injectors and stupid ACCEL wires <----Never run these. NGK instead.

 

[Talonman86096]

Just curious, do you have a 6 bolt swap? Your mods list doesn't have anything listed.

 

[CcrayzZ]

What Kind of plugs are you using? both brand and quality

 

[TurboTylerT]

The plug wires are Taylor 8mm or 10mm. The plugs are brand new NGK iridiums. The spark is the same on all cylinders. I changed the power transistor but that didn't do squat. I also checked for boost leaks and leaks elsewhere. I came up with nothing again. I have this silly maf translator that seemed to fix it some while adjusting on it, however it took over the afc controller. I reset the maf to 0 except for the injectors that have to be set on. Under boost now it goes rich, and the idle is still lean even if I add a ton of fuel it doesn't wanna budge much.

 

[clipto]

The plug wires are Taylor 8mm or 10mm. The plugs are brand new NGK iridiums. The spark is the same on all cylinders. I changed the power transistor but that didn't do squat. I also checked for boost leaks and leaks elsewhere. I came up with nothing again. I have this silly maf translator that seemed to fix it some while adjusting on it, however it took over the afc controller. I reset the maf to 0 except for the injectors that have to be set on. Under boost now it goes rich, and the idle is still lean even if I add a ton of fuel it doesn't wanna budge much.

So you have a maft and a safc? Do you have stock 450cc injectors? Did you zero out the maft and the afc? Rich under boost do you mean like like the stock a/f ratio under boost is like 9:0? I had car that was lean warming up was getting 16:0-17:0 a/f ratio and it was popping because it is lean is that what you think the missfire is? Does it go back to normal after driving a little? Could be exhaust leaks.

 

[TurboTylerT]

I found that the cam caps were in the wrong order so that helped some. I did a complete rebuild but now I am to the point of a stand alone system. This guy shafted my ms2 so I am still trying to find a harness that is plug n play. A stand alone is a must right now for me to get rid of the maft translator. Ill keep yall posted but I can't do much without an ems.

 

[bucken13]

I recently got this to . But mine was after i installed a new clutch assuming that is what caused my issues i have dsmlink so i was able to disable the Code and havent had any issues since. Have you considered buying link ? What size injesctors are you running ?Also your a 98 you should be able to reflash your ecu and at least ditch the AFC.

 

[bmxfelon420]

Dont run Iridiums in a DSM. BPR 6 or 7 ES are good for 99% of builds. I'm sure there's some crazy build that would run colder, but for the most part thats the only plug you'd ever want to use.

 

[curt-s]

I'm beginning to think Taylor wires, the 8mm variety of Spiro Pro, are just.. not quite up to par. Interestingly enough, I've been shocked through the boot on one when I adjusted a plug while the car was running. That shouldn't happen; tells me the dielectric strength isn't very good, and can cause this.

I really think I'm going to go NGK 7mm this year and skip the P0300 altogether ;p