Nnbs Idle

[Mossyoakglock]

I have an 08 Silverado 5.3L w/ about 23k on it. My truck idles around 500 rpm, but will occasionally drop a little and have a little bit of a shuddler/shake (not to where the truck shakes, I can just feel it in my seat). When I say drop a little, I mean just below the 500 rpm mark. Then it will go back to normal, or maybe a little over the mark. I notice it does it more when the AC is on, but sometimes without. For you guys with an NNBS, what does your truck idle at and does it do what mine does? I thought I read on here that somebody with an 09 had a throttle position sensor that was bad, but mine doesn't do it anywhere near what his did. Could I have a bad sensor or should I just run some cleaner through it or Seafoam it and see if that helps?

[68haywagon]

My 07 did that and the dealer said it was normal and my new 09 does the same thing. The shudder is annoying but I'm used to it now.

 

Mike

[RyanbabZ71]

my 08 Tahoe idles at 500 and it doesnt move from there. It has a little over 8K miles.

[Mossyoakglock]

I haven't checked my air filter in a while, so I will do that just to check. I cleaned my MAF sensor and throttle body not to long ago and it helped a little. Maybe it's normal and I'll just have to deal with it.

[qwk93ta]

I have a 09 Silverado EC 5.3 Flex, it idles at 500 and is smooth.....however, I only have 1,800 miles on it.

[fbachman]

500 here. rock steady, except when cold in choke cycle --- oscillates between 500-800 and idles a little rough. Once it warms up, 500 and holding... Other than that...

[Spurshot]

I have an 08 Silverado 5.3L w/ about 23k on it. My truck idles around 500 rpm, but will occasionally drop a little and have a little bit of a shuddler/shake (not to where the truck shakes, I can just feel it in my seat). When I say drop a little, I mean just below the 500 rpm mark. Then it will go back to normal, or maybe a little over the mark. I notice it does it more when the AC is on, but sometimes without. For you guys with an NNBS, what does your truck idle at and does it do what mine does? I thought I read on here that somebody with an 09 had a throttle position sensor that was bad, but mine doesn't do it anywhere near what his did. Could I have a bad sensor or should I just run some cleaner through it or Seafoam it and see if that helps?

 

Sounds like the A/C compressor clutch cycling. Only reason it would cycle the A/C clutch when the A/C is off would be if it was in "defrost" mode, from what little I know. Make sure you don't have it in either mode when you check it. Also, a bad EGR could cause idling probs. Probably a host of other things as well.

[Crazy Canuck]

Mine idles right around 500 (or slightly less) as well. I also feel the bit of vibration once in a while and I believe it ios when the compressor cycles on. I don't worry about it, I don't think it is a big deal. I think the ECM just needs that split second to adjust to the load increase.

[2005LT]

mine sits around 500 too and has a light vibration every so often. Doesn't seem to be the A/C clutch though as the vibration is quite random. Does this at stop lights with foot on brake or in park. I wouldn't worry about it.

[brims]

Mine does that all the time, when it drops to just below 500 it gets bad but then the tach jumps back up and isn't as bad. If I kick up the idle to 550 or so, that crap stops.

[Unknown123]

i got a older truck, and mine does that. its idles around 600 but it well drop, then go back up a few times when it sits in park.

[cliobogger]

its compleetly normal.

[huero626]

When I turn on my truck the RPM shot up to 1000rpms but it drops to 500rpms when it idles.

[Wires]

I have an 08 Silverado 5.3L w/ about 23k on it. My truck idles around 500 rpm, but will occasionally drop a little and have a little bit of a shuddler/shake (not to where the truck shakes, I can just feel it in my seat). When I say drop a little, I mean just below the 500 rpm mark. Then it will go back to normal, or maybe a little over the mark. I notice it does it more when the AC is on, but sometimes without. For you guys with an NNBS, what does your truck idle at and does it do what mine does? I thought I read on here that somebody with an 09 had a throttle position sensor that was bad, but mine doesn't do it anywhere near what his did. Could I have a bad sensor or should I just run some cleaner through it or Seafoam it and see if that helps?

 

It's normal. They run these things super lean with a super low idle for better fuel economy. The speed an engine cranks over at is around 400RPM. I'm surprised that EFI can keep an engine even running at that speed! Pre-EFI you'd need to keep the idle at 1200-1400RPM to keep a V8 idling.

 

My '00 5.3L did that, so does my '08 6.2L as well as my BMW car.

 

The AC is going to toss more load on the engine and enhance the effect. If it was dipping a lot (300 RPM for example, then I'd suspect an issue.)

[Ghostwhite]

glad I found this thread again. my wandering idle is more apparent after my exhaust and intake was installed. 450-550 it just wanders