I wanted to get some input on what can cause the idle to have an extra beat when car warms up on idle or after a long drive. What I meant is, during start up, the evo idle has certain beat as the cylinder fires. You can tell that its timed, i.e, it fires up at a regular constant beat - (blub-blub-blub-blub). RPM Idle is steady around about 1000 rpm.

When the car warms up or after I drive, there is an extra beat I hear that makes the beat somewhat off. The idle rpm still remains steady, the sound out of the exhaust muffler is constant but seams to have an extra beat added in between. Other than that, car is good. Can this be cause by bad fuel injector or bad coil pack or something else. How many miles do oem fuel injector or coil packs last?

Evo has 135k miles. Original fuel injector and coils. I do have a walbro fuel pump upgrade and EBC, Tune, downpine, catback, ets IC..

Thank you for your advice. Happy Thanksgiving...

 

Post up a video of the idle so we can hear the sound.

 

I mean, when its cold its closed loop so it would be a steady idle. When it warms up its searching for a balanced mix so could make it sound off. Thats just my thinking, could be wrong.

 

When it's cold it's actually in open loop. Closed loop idle in the stock US ROM starts at a coolant temp of 84 deg. F.
This is not something that can be diagnosed with a description. Post a video if you want us to help.