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Im more than sure this has been spoken about once or twice but im not finding anything usefull. I picked up a 93 z28 and it ran fine for a few weeks. but now its developed a really bad miss under load. Car has 127,XXX miles and the service record for the past opti and plugs and wires was at 122,xxx miles but it was back in Oct or 2014. Car sat for about 6-8 months before i picked it up. symptoms are a small little ticking noise (sounds electrical related not like a mechanical part) while cruising but if i downshift and put the pedal down it starts to jerk and miss. no cel or anthing on the dash. im thinking plugs and wires might be the issue but before i spend some money i need feedback. THX
Useful things to do:
Check condition of spark plug wires to see if they are at all cracked or show signs of, they need to be replaced. Start car when it's completely dark. Look for arcing. Give throttle body a few quick blips.
Tick could be a loose spark plug. You can tell if it's an exhaust leak if you put the engine under load at a low rpm and the tick gets louder.
Check fuel pressure without vacuum attached to fuel pressure regulator. Should be between 42 and 45psi. Optimal is 43.5psi.
Usually when it misses under load it's a fuel or spark delivery problem.
Useful things to do:
Check condition of spark plug wires to see if they are at all cracked or show signs of, they need to be replaced. Start car when it's completely dark. Look for arcing. Give throttle body a few quick blips.
Tick could be a loose spark plug. You can tell if it's an exhaust leak if you put the engine under load at a low rpm and the tick gets louder.
Check fuel pressure without vacuum attached to fuel pressure regulator. Should be between 42 and 45psi. Optimal is 43.5psi.
Usually when it misses under load it's a fuel or spark delivery problem.
Thank you, I’ll check fuel pressure but I’m not 100% that’s the issue the car does run a little rich and will pop and back fire when I downshift coming to a light. But I’ll certainly check it. Now that you mentioned arcing that’s kinda what the ticking sound sounds like. I do have an exhaust leak my header gasket behind the alt failed and this new tick is quieter and doesn’t sound mechanical. My coworker mentioned that the wires probably have a short due to the car sitting through or monsoon season this and last year (I live in AZ so summer storms are not small or light). But thank you again
I have a stock lt1 that will burn the wires every other year. It has all the factory heat shields but it still does it even with delco wires. It will pull timing and in a manual car it can make the top gear not fun under load.
I'm too lazy to take them all off so I will pull the ends off and use a multimeter to figure out the culprit.
stumble under load..."tick" sound. Classic plug wire/boot arc
You may not be able to see the arc from up top. May have to get under car while running to see every plug boot entirely
You have those metal head shields on plug boots?
remove them
If no plug arc, likely Opti issue. Especially if the replacement Opti is not a AC Delco
you were right, I did the plugs and wires today along with the coil on Saturday, still wouldn’t crank up so I replaced the icm today too and it cranked right up, I didn’t hit the oil pressure sender wire and broke it so I gotta replace that too now but it starts and runs I just have yet to see if my misfire has disappeared cuz I’m not driving while it says I don’t have oil pressure
Hello there. Did you fixed it? I have a 96 camaro SS after the cam, head mods the car ran fine as long as I was not trying to push hard.... anything over 5000 rpm it felt you were hitting the rev limiter.
I resistance check the plug wires and visually inspected the wires the best I could (the right side is very hard) and found nothing. I gave up like a year ago. A few months ago I decided to swap the engine I had from my 95TA ( forged 383 with a nice cam and LE2 heads) when I drop the k member and rolled out the camaro engine out the
cylinder 4 plug wire was completely burned through but is was on the part of the routing you could not see.... make sure you keep those wires away from the headers... on my new build I will put insulation sleeves on the ones on the right side that are close to the headers.
Best to run plug wires through all stock brackets & looms or mimic that or otherwise a burned wire or boot in a area you can't see will burn and then you get arc/misfire
Best to run plug wires through all stock brackets & looms or mimic that or otherwise a burned wire or boot in a area you can't see will burn and then you get arc/misfire
brother I learned the hard way... I had a perfect good 400+ rwhp car and we were not able to diagnose the burn wire by looking for arc or visual... we used most of the stock brackets but the issue here is the MSD cables are thicker and do t fit well.... any suggestion there for my new build? I was planning to use original routing as much as posible and use the insulation sleeves on the right side for the routing closer to the headers.
any suggestions will be appreciated. I still closing my 385 and should be mounting on on the k member after Christmas
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Bad miss under load 
