question: why engine shakes?

[rnln]

I know this can be caused by many reasons but I will describe as detail as I can and hope someone can point out the cause.
My car usually smooth/perfect idling, at around 750 rpm. It had platinum plugs before I replaced them. The engine now is shaking slightly, after I replaced plugs and oil change. The rythym is like an old v-8 truck. The plugs I replaced with is NKG BP7ES. When looking at the car, and engine idling, you won't see it shaking, unless you are sitting in the car and it only does that when idle. Soon I step on the gas, even slightly to raise the rpm, no more shaking.
Someone might tell me to adjust mixture, or tune up. But the shaking wasn't there before. Appears right after I chagned plugs. Is it because something with this type of plug? I regaped them carefully before I installed them, between 29-30, and I tight them tight.
What else can I check into? If drive the car this way for a while, will it damage anything?

[JoeyD911]

How old are the wires and how rough were you with them? could you have damaged a connector pulling the off? Seems like that's the only other thing you touched. Mine idles a little rough too. Mine is an occasional miss that I have yet to put the time in to properly diagnose and fix. Benn running that way for the last 3k.

[Scott R]

Maybe a miss-fire, I'm the king of causing those. I've done it all, smushed a plug gap shut, broke a Beru connector, not getting the "snap" when connected, reversed a couple of wires. Probably something simple like that.

[Jim Sims]

Perhaps a loose spark plug wire; check that the connectors are all properly seated onto the top of the spark plug. One should hear/feel a "pop or click" as they seat.

[rnln]

I don't know how old the wires are since I bought the car used. The connector and holders said Bery. I also check for night light dance blah blah at night but they look ok. I also checked again and again by pulling each wire off and pushed it back in with a click, some I can hear very lightly but it's there.
If it's missing, why it's only missing at idle, not when having some rpm?

[dshepp806]

Did you touch the distributor or rotor, at all?

What, exactly, is "tight"?

A plug changeover? Type/brand?

Maybe time to check your ignition wires (aside from the click),...how old? Terminations ok?

Scott R is dead on to "having been there, done those stupid things" Check,..then recheck.

Hopefully something quite simple, as things were alledgedly ok before the work, right?

Best,

[rnln]

Did you touch the distributor or rotor, at all?
- Yes. Try to look in there if need to clean up or replace. It look worn, but maybe ok.

What, exactly, is "tight"?
- well, tight with my hands.

A plug changeover? Type/brand?
- from platinum to NKG BP7ES

Maybe time to check your ignition wires (aside from the click),...how old? Terminations ok?
- yeah, will do again this weekends.

Scott R is dead on to "having been there, done those stupid things" Check,..then recheck.
- Agree.

Hopefully something quite simple, as things were alledgedly ok before the work, right?
- Hope so.

Or maybe when I install the cap back on, I didn't install it at the center? meaning it's off to one side? Is it possible?

[Superman]

I took my wires and cap out of the car the last week to test continuity. Then I reinstalled. I made sure the cap went onto the distributor properly, verified that the #1 plug wire was in the proper orientation, and them proceded to snap the plug connectors on the other plugs with the certain knowledge that the distributor shaft rotates in a clockwise direction. The car ran like it was firing on only two cylinders. I checked and rechecked everything several times. Later, I noticed the sticker in the engine compartment that alerts intelligent owners that the distributor shaft rotates in a counterclockwise direction. Obviously, that does not apply to owners like myself.

[rnln]

...because you are superman :lol: