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Rough Idle On Cold Start 07 Nbs

zgranj

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zgranj Enthusiast

zgranj

Posted
Posted

Anyone experienced a rough, erratic idle on a cold startup of a NBS 07 5.3l Silverado with Active Fuel Management?

krww06 Enthusiast

krww06

Posted
Posted
Anyone experienced a rough, erratic idle on a cold startup of a NBS 07 5.3l Silverado with Active Fuel Management?

 

 

Yes. Mine is an '07 Silverado NBS. It happens every single time I start it (first thing in the morning), and doesn't reappear until the next day.

K9Blitz Enthusiast

K9Blitz

Posted
Posted

The rough idle comes and goes on mine. The electric fan kicks off and on regardless of AC or outside temps. That's loud and bothers me as well.

 

I hope to bring it to the dealer next week for it's first check up. I'm also getting a transmission "bump" when I'm stopped at a light in gear with my foot on the brake. It feels as if someone lightly rear-ended the truck.

 

I'll keep you posted on what the dealer says.

Big Tool Enthusiast

Big Tool

Posted
Posted

I've noticed both mine and my dads gmt-900's 6.0 and 6.2 both make the same sound when cranked in the morning with the remote start. Goes away after about 2secounds. I don't think it's nothing to worry about. My 2000 sierra 6.0 has had piston slap forever and still cranks every morning now as it approaches 190k.

my07silvy Enthusiast

my07silvy

Posted
Posted

I think the truck sounds pretty good on cold startup! Is anyone else with me on this? I think it sounds tough like it's got a nice cam in it for a few seconds...No complaints here!!!!

Big Tool Enthusiast

Big Tool

Posted
Posted
I think the truck sounds pretty good on cold startup! Is anyone else with me on this? I think it sounds tough like it's got a nice cam in it for a few seconds...No complaints here!!!!

 

 

I know what you're talking about it's got a nice lope to it, but i'm refering to more of a piston slap noise.

Slider_4x4 Enthusiast

Slider_4x4

Posted
Posted
Anyone experienced a rough, erratic idle on a cold startup of a NBS 07 5.3l Silverado with Active Fuel Management?

 

 

Mine does this too. Usually it isn't too bad, but sometimes it feels like it surges a bit when I first start to drive away.

 

I'm also getting a weird whistling sort of noise (like a squeaky belt) when I first start up in the mornings. Anyone else hearing this?

 

Thanks.

jdolotina Enthusiast

jdolotina

Posted
Posted

I get the same thing on my 6.0L too. Sometimes cold starts cause a waivering idle. I do get a squeak under the hood also on cold starts like a belt is loose. Anybody know what it is? Maybe there is a TSB for it. WHat do you know, when it warms up it runs smooth as butter. My o4 use to have a belt squeak too, but here in the arm pit of America (Shreveport, LA) it is real humid in the morning. I wonder if this crap is normal.

 

Josh :)

krww06 Enthusiast

krww06

Posted
Posted
[......snip] I'm also getting a transmission "bump" when I'm stopped at a light in gear with my foot on the brake. It feels as if someone lightly rear-ended the truck.

 

I'll keep you posted on what the dealer says. [.......snip]

 

I get that too. However, it usually occurs when I'm almost at a stop, but not quite. For example, often times it happens when I'm pulling into the garage. It scares the s*** out of me, b/c normally it'll "surge/bump" when the OH door is about 80% of the way up, so I think I'm going to crash into it.

skytop Enthusiast

skytop

Posted
Posted

My new '07 Denali idles rough all the time. I used to object to it but have become accustomed to it. Now only people standing next to the truck as they talk with me make mention of the shaking feeling in the doors as the engine idles.

 

Dealer states this behavior is "within normal operating parameters of the vehicle." That's what they say about all the many problems I have with this truck.

07LTZ Z71 Enthusiast

07LTZ Z71

Posted
Posted

Hi everyone! New here to the forum.

 

My 2007 NBS 6.0L will have a rough idle on a cold start too. It only happens when the temperature is above 85 degrees outside and would vibrate for 15 to 20 seconds. I also took mine to the dealer. Only thing the dealer did was to update the ECM & TCM for the V4/V8 hesitation. My dealer has a TAC cas with GM with this issue. It was 90 degrees yesterday and the vibration was there slightly.

killermini Enthusiast

killermini

Posted
Posted

well i was starting to think there was something wrong with my truck when i started it up in the mornings. my 07nbs sierra shakes at start up also. does feel like i have a cam in it. makes me actually want to put a bigger cam in it.

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