Have any of you guys ever done new plugs and noticed a slight power increase and crispness then after a few days you get used to it?
My gain was like 2-3 times that, nothing outrageous, but enough power it sounds throaty at idle and you notice it every time you drive it.
Very hard to verbalize or quantify by us average joes.
I genuinely think some Jeeps run better, and not all owners will notice equal gains.
A healthy guy doesn’t feel the vitamin shot like the guy who needs it more.
New plugs can absolutely make a difference if the old ones are bad or out of spec.
Worn or fouled plugs can fail to ignite the mixture every time, which means that the fuel/air is wasted and burns up in the catalytic converter instead. If it doesn’t occur often enough, you may not get a misfire DTC.
A spark plug that is weak tends to create a smaller flame kernel, meaning it takes more time for the kernel to grow and eventually generate peak cylinder pressure. This tends to cause an effect similar to pulling timing, in that the peak pressure occurs later than it normally would, meaning the engine extracts less power from the burn. On the opposite end, too large of a spark can cause very rapid kernel growth and advance the peak pressure time before the intended target, which can either cause a reduction in power (more pressure pushing on the piston before it reaches TDC), and in some cases, cause detonation (pinging).
Having the wrong temperature range spark plug can also cause issues. Too hot of a spark plug can cause preignition, which tends to quickly cause engine damage as well as cause peak pressure to occur earlier than intended, reducing torque output. Plugs that are too cold will get fouled, which may cause weaker spark, or in some cases, also cause preignition due to the carbon build-up.
Similarly, tune timing makes a huge difference. The OEM charts are very conservative, meaning peak pressure often occurs way later than it could, reducing torque output unnecessarily. On a poorly maintained engine, this can help extend its longevity. However, on a well maintained engine, it primarily results in reduced power/torque and increased fuel consumption/emissions.
