bad misfire on 5.7 vortec

[ccapehartusarmyINF.(ret)]

just for ***** and giggles make sure your plug wires are wired for the right firing order

 

[westman995]

They are on correct. Just put them back on when I had the cap off.

 

[Ironman1979]

have you checked to see if you have fire to each cylinder.. if so that rules out the cap and rotor and wires.. if theres no fuel on those plugs that arent firing you have a fuel issue and probably need to upgrade the fuel spider to the delphi with the individual injectors... its an easy job takes about 2 hrs and a case of ber and some good tunes.

 

[ezdaar]

get a spray bottle. one that spray a nice fine mist, fill with water.
Fire engine up. turn off all lights. start spraying ignition system.
Look for the rave party.

 

[westman995]

I tried the spray bottle thing. The clicking noise I was hearing was definitely a spark. I put dielectric grease on all the plug ends.

I seen the wire off the coil arcing out on the trans fluid tube so I rerouted that.

I also seen some arcing between a couple plug wires on the cap.

After I regreased it all, I couldn't see anymore arcing. But the noise was still there. I either couldn't find it, or its arcing inside the cap. Which is what I'm hoping.

I have a new ac delco cap and rotor on the way. I will post up whatever happens after that. Plug wires are almost new ac delco. Plugs are cheap autolites, plan on replacing them with ac's soon.

 

[ezdaar]

You can save a significant amount of money buy using ngk tr5 if you run 93 or tr6 for all gas if you want.
A quick google search will get the part numbers so you dont have to argue with the retard working at what ever parts place you go to.
Just tell them give me 8 of these, heres part number...
Or they will tell you they wont work with your engine because its not in their system.

 

[westman995]

Ill look into that after I figure out what my problem is.

So I've replaced the cap and rotor with new ac delco parts. Made zero difference. I just checked again to be 100%, there is spark on the dead cylinders. I pulled the plugs from dead cylinders and they aren't soaked or anything. They just barely look wet but they don't smell of gas as far as I can tell..

So I'm going after the injectors now. I was hoping it wouldn't be that since they're under the plenum. But I have an extra spider from the old motor so I'm going to swap out the injectors on the dead cylinders with some other used ones.

Eventually I'd like to upgrade the whole thing to the newer/better style. But money is tight and if this fixes it, it'll be a free fix

 

[Big Roller]

Have you checked your ignition coil? Mine went bad and it would miss like crazy, jump, spit and sputter, do everything but run the right way. I even changed plugs, wires, cap and rotor trying to chase it down. Didn't help at all... then one dark morning I decided to look under the hood and there it was.... An arcing ignition coil. Changed it with an MSD coil and never had a problem since. Maybe worth a shot instead of tearing everything apart getting to injectors.

 

[westman995]

I have not checked it. I kinda ruled that out since it was 3 cylinders constantly not working.

I did pull everything apart and swapped out the injectors on all three cylinders that weren't firing. The good thing is that was the problem. The bad thing is that fixed two of the cylinders, now one still doesn't work so ill have to take it all apart again. Its not too horrible of a job. I guess I'm just glad I finally found the problem.

The truck is at least drivable now so I'm going to run some cleaner through the fuel and hope that it starts working. If not ill just try another injector.

I notice that the pcv valve is pretty loud. Is it supposed to be very audible or should it be pretty quiet? It sounds like possibly some arcing but hard to tell with that valve being so loud