I've heard a few of my friends with Vettes complain about it, and maybe a few with trucks as well, it happens on my 2000 5.3L.

Idling in gear with the foot on the brake and intermittently getting a vibration/shudder from the engine. Is it because they have these things idling too darn low? Anybody ever come up with an answer?
It's not really a big deal, just kind of annoying at times.

 

Is your A/C on when this happens? The A/C clutch will put a load on the motor when engaged. With mine off, there is no shutter on my truck.

 

Mine did this at idle all the time. I'm not sure if it was because it idled too low or not. My truck idles at 500rpm, but I think it should idle at 525rpm. Once I installed the electric fans, it stopped though. I never run my A/C, but its kinda wierd that once the old fan clutch came off, the problem stopped. If the vettes do this, then I have no clue as to what causes it because they have electric fans. <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

 

A/C is not on when this is happening, but that scenario yields another wonderful noise....the big metallic thud when the compressor kicks on/off.

My idle is also 500rpm....which to me just seems to low.

 

You know you want a WRX!

Get LS1Edit and raise the idle a 100 rpms...

 

If a WRX could tow a Z28 you know I'd have it already <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

For now, I will stick with the Chevy truck and it's shortcomings (sigh)