Developed a pretty significant miss in #4, i know it's #4, header is touchable compared to the fried skin on other primaries after short run.

I just changed out the plugs and wires, had brand new ac plats 41-906, i think, gapped around .050-.055. changed to #14 rapid fires gapped .060. All plugs looked good, #5,7 were pretty funked up w/ carbon, #4 full of fuel. It also had brand new 7mm autolite wires. Changed them out w/ cheapy lifetime from autozone to see if it makes a difference.

fired it up, still seems like it's stumbling. plug wire ohmed out good, spark plug was covered with fuel..

just changed out opti cap and rotor, cleaned out rest of opti w/ electric parts cleaner. was missing before, and had leaky water pump, so i thought it just needed the normal stuff.

I know the opti is optical pickup, but does it tell the computer what cylinder it's on? why #4 always misfiring? If it tells which cylinder it's on, i am probably going to have to invest in the back half of the opti, huh? it is the unvented splined shaft, don't really feel like converting over to the vented.

IF it doesn't tell the computer what cylinder it's on, how in the hell is #4 missing all the time? I'm clueless, confused, and want to get this sumbitch on the road!!!!!!

thanks,

Jeff

 

A buddy had this problem on a different engine (390 fe) that he triple checked wires, plug, and rotor ,cap and when all that failed we took off the valve cover and found a broken valve spring. Not saying thats what you have but if you have spark going to that cyl and its gas fouling I'd pop the valve cover off and take a look at that. At least eliminate that as the source, because its pretty unlikely the opti or coil could be the cause of one cylinder not firing.

 

Thanks for the reply, the motor seems to have a little valvetrain noise at idle, waiting on getting service manual to check them and possibly adjust them if need be.

I haven't checked for spark, I need to put a plug to ground and see if it fires.

Does anyone know exactly how the opti works/what it does? I know it's just universal pattern on the optical pickup disc, but what is it telling the computer, what frequency to fire the injectors at, or what? I would like to maybe ping the engineers at my work for a better solution to this problem.

Thanks again,

Jeff

 

ok, did compression test, all the cylinders are reading 198-202 psi except for #3, it's reading 166. low, but still ok, right?

http://www.hpphoto.com/servlet/LinkP...44a3d652&size=

(Front of motor is top of pic, odd on left, even on right.. bird's eye view)

hmmmm... wonder what is wrong with my truck....

hehehe, after walking past it for the past two weeks glaring at it and entertaining thoughts of sledgehammers and pickaxes, I got up the nerve to work on it. I decided to start small, pulled the four bolts out of the fuel rail, removed the injector harness, and pried the rails up. bottom of the injectors looked spotless. damn.. so I said, well, after what everyone told me to do, check the injectors, I pulled #4 just to take a peek. HOLY HORNY TOADS!!! I had about a ounce of crap pour out over my hand and #4 is completely packed w/ rust and crap!! I guess from it sitting for so long the lines rusted up, then w/ the high flow from the v8 and high pressure, it knocked all of it loose. I cleaned out the injectors using dental picks and carb cleaner, my god it screams once again!! I cleaned out the fuel rail, fpr, and tried to flush the lines. I also installed a huge inline filter before the fuel rail.

I ran a 0-60 mph run w/ a 175 lb passenger, 6.26 seconds. Anyone have their times? Just wondering how that compares.

As soon as my new laptop arrives I am going to monitor everything to see what my maps are set like, maybe get into tuning it now. hehe, going to install my crane cams hi-6 ignition monday night.

I am also in the market to get new/used injectors either stock or larger. with my mods listed below, can anyone make suggestions on what I should get?