I apologize for another I'm in denial is it the opti? I developed a terrible miss. It would clean up in the higher rpm's. It started off acting like a burnt plug wire. My wires are routed over the valve cover. So I know one wasn't laying on the header burnt. I pulled the plugs, and they all looked fine except for #8 which was dark (not oil foulled, but it looks like it is running rich). I swapped in brand new Autolite 104's gapped at .040. It ran great for about 5 miles. Then the miss came back same as before. I checked #8 and it wasn't fouled out. I also did a compression test at this time which they are all close to each other within 10 psi. I made new Taylor wires for it, and it ran good for half a day. I acually messed up putting one of the new wires on the opti, didn't get it seated properly, so it popped off and met up with my fan belt. I could also see arcing from 4 of the plug boots, and an arc where the opti boot came off. I ordered a new set of wires and put them back on, miss is intermittent, but much better then before. I took it out for a long drive on the highway and I could feel it miss till about 3000 rpm then it started to clean up. After a few more miles the miss went away, and it came back when I would accelerate from a low rpm in a lower gear than normal. I pulled all the plugs, and # 8 is dark, the others look perfect. I have had a stethiscope to all the injectors and I can hear all of them ticking. None of them sound any different than the others. So I guess tomorrow I will pull the opti and inspect for any damage to it.

Thanks:

ZMAN Z28

 

A miss will be more pronounced at a lower RPM and higher load. Sounds like ya may have some carbon tracking in the opti from the long time miss (common).If the spark don't jump the plug it comes back to the cap(with good wires) and jumps to the nearest thing it can find(gotta go somewhere)in the cap(once it has jumped once there is a clear path to jump again).This is one of the reasons I don't run certain plugs and gap the ones I run at .035.To cold of a plug is no power advantage,except at the track,talking putting them in at the track and taking them out at the track to go home. Most are not at the power level that they do any good.

If it don't say Champion,AC, or Autolite,I don't fool with them.Just my preference that I have had good luck with for 40+ years.

Pull the cap and get it just right in the sunlight and ya will probably see fine lines that look like cracks.It's not,it's carbon tracking. If ya want to go through the work to prove it take a pencil eraser(The only thing I know that works-no brake clean,solvent,ect.) and erase the lines completely and try it. It will work for a while,but will tell ya if that's the problem before spending $300.00.

 

Have you monitored the fuel pressure after the engine is shut down? I suggest you check a few items with regard to #8. Swap the #8 injector with another good cylinder and see if the problem of "blackening" the plug follows the injector or stays on #8. If it stays on #8 do a leak down test on that cylinder.

 

Thanks, I never thought of that. It should be one more easy thing to do before I pull the water pump. Afterall, it's a 3 day weekend, so there won't be any shipping of parts before tuesday.

As far as the fuel pressure after shutdown, the pressure drops. But I also have a Walbro 255 fuel pump, and after I put that in, the fuel pressure after shutdown has never maintained 40 psi give or take a couple, but drops down to about 20. But as soon as I turn on the key, the fuel pressure jumps up to 40.

Thanks:

Z