My question is this: I have an 88 iroc 5.7 tpi automatic with hypertech thermomaster with cooler thermostat ,K&N's and a throttle body air foil. that ran great before installing the msd parts and now it runs awful and misfiring bad! I installed: Msd cap Msd rotor NGK plugs gapped at .040 5000's over factory gap (.035) MSD 6A ignition MSD 8.5mm spark plug wires What I did to check so far: I made sure that the gap on all of the plugs are same . made positively sure firing order with plug wires is exact with distributor cap. I have 2 different wiring diagrams with the msd ignition for my dual coil connector. I am kinda sure I wired it up right, I could be wrong! made sure cap and rotor fitted properly. Its gotta be something I did because car idled great before now runs awful it idles like it had a big cam it it and makes light knocking noises. I love my car please help me out. Thank you!!!! Chris

i did plugs and wires when i first got my car and it idled like hell. i check my firing order and it was right. a few days later of being sick of the performance, i checked the wires again, underneath the manifold i had two wires sort of wrap around eachother and it was impossible to feel this, and when you tugged on the wire it felt like the right one was moving, but it wasnt becuase of the way the wires were crossed. if you wired up your msg correctly, id try checking your TPS and IAC. do a seach for them, i know that stuff causes bad idles.

It does sound like two wires are crossed. To make absolutely sure, put engine at top dead center on the timing mark. The rotor will be pointing to #1, go from there with the firing order, each wire from plug to cap. gets tight in there, easy to mess up (experience talking here). Like what is said in plenty of posts: do the easy stuff first before digging deeper.

Plus that light knocking sounds like a plug firing when its not supposed to.