97 5.7 strange itermittant misfire

[agent319]

Ok, but what brand are the cap, rotor, and wires. vortecs don't like cheaper components here. Does your cap have a vent? If you bought the cheapest plug wires at advance they are definitely crap by now....

You could also get your coil and module checked....

I bought them at Oreilly. I don't think the cap has a vent. What does the vent look like?

 

[agent319]

Ok, I isolated it to my plug wires. I went to Harbor Freight and purchased 1/4" protective wire wrap and put it on my plug wires. I did that because when I hooked up the timing light I was getting intermitent firing on 2,1,5,7. It could eithe be the dist. cap or getting cross fire from old plug wires leaking where they were touching. Sure enough she ran like a champ. The wires are wore out. Anyone suggest a good set that won't break the bank?

 

[SAATR]

Ok, I isolated it to my plug wires. I went to Harbor Freight and purchased 1/4" protective wire wrap and put it on my plug wires. I did that because when I hooked up the timing light I was getting intermitent firing on 2,1,5,7. It could eithe be the dist. cap or getting cross fire from old plug wires leaking where they were touching. Sure enough she ran like a champ. The wires are wore out. Anyone suggest a good set that won't break the bank?

With wires, you generally get what you pay for, as there aren't many places that corners can be cut without a noticeable loss of quality. For GM vehicles, ACDelco are the standard by which all others are judged, and will serve you well if you can stomach the price. That aside, I generally say get the best set that you can afford, and remember to route and loom them correctly. I cannot overstate that the routing and protection of your wires is one of the most important considerations when it comes to their lifespan. Factory wire sets have a dozen clips and retainers for this very reason. Heat, chemicals, and abrasion severely shorten the life of the insulation, which in turn causes voltage leaks and crossfire/misfire conditions. Even if it means you have to go slightly cheaper on the wires, you will get the best possible life out of them, which will be longer than a set of OE or name brand wires that are rubbing on the exhaust manifolds or getting stress fatigued from flopping around the engine compartment.

 

[bluex]

I have 10mm livewires from performance distributors. They are only slightly more expensive than AC delcos.

I can't find an online picture of a vented cap, I will put one up of mine but it sounds like you found your problem.

If you wondering I got my cap (vented with brass terminals), rotor, wires, coil and module all from performance distributors....

Here is a link to their wires http://www.performancedistributors.com/chevlivewires.htm I used the over the valve cover kit part # C9047

And the tune up kit I got http://www.performancedistributors.com/vortec.htm this shows all their vortec stuff the firepower kit includes everything but the distributor....

 

[agent319]

So I replaced my sparkplug wires and not with AC-DELCO but with OMNI Spark. I put boot silicone on and was still getting missfire going down the hwy. Not as much. So when I got home after dark I opened the hood and looked around. Two sparkplug boots on each side of the engine where flashing which means they were arcing and not getting the full wattage of the spark and stubbling I'm assuming. I also saw some intermitent flashing going on at the coil. Is that a concern? Anyway. New spark plug wires didn't help my intermitent missfire.