Engine shuddering, only during idle - tried few things..

[alia176]

Hey guys,

I've been experiencing what I describe as a engine shuddering/misfiring problem. This is very noticeable during idling but not any other times. Engine acceleration is very smooth, fuel consumption hasn't changed for the worse. However, under load during idling, like the A/C on, the engine stutters fairly bad.

Now this is going to sound strange but I seem to hear a "tick" precisely a moment before the misfire/engine shaking commences. This "tick" sound was very strong on the driver side of the engine, near the valve cover area. Again, this is not a rhythmic tick, just a random tick before the engine shudders. However, today, I followed the sound to the passenger side of the engine, around #1 spark plug.

During the first startup of the day this morning, this ticking sound, followed by the engine shuddering was intermittent and erratic. I'd say, about once in ten seconds to about once in 20 seconds. However, after returning home from a "spirited" driving, this phenomenon was occurring more frequently, I'd say about once every second to once every three seconds. Sometimes even four or five seconds in a row.

I'm leaning toward an ignition related issue over air flow or vacuum leak because ALL vacuum hoses were replaced last week! I have no CEL and the intake air hose seems to be in fine shape. Also, I just did the engine re-seal project at the same time.

Just as a reminder, I have NO engine issues once the car is driving. No acceleration hiccups, stalls or strange RPMs. Can I assume that the MAF is fine since I have good performance past idle? Battery is strong and the tank is full of 91 octane.

I took some videos and going through them now but the quality isn't the best (using a digital camera for video). I'll add a link once this is completed.

I unplugged the injector connector one at a time and this makes the engine shudder far worse than what I'm experiencing currently. Each injector is making a rhythmic ticking sound as confirmed by the mechanical stethoscope.

As of now, I need to figure out what item is getting hot and electrically misbehaving. I'll look at the igniter and clean up some grounds for starters. I'll pull the spark plug on that cylinder for inspection. If there is something else I need to focus on, please let me know.

Thanks.