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Gm V8 shaking in idle #4557532
10/28/17 06:23 PM
10/28/17 06:23 PM
Joined: Apr 2004
Posts: 439
ON, Canada
yugrus Offline OP
yugrus  Offline OP
Joined: Apr 2004
Posts: 439
ON, Canada
I have '14 Tahoe with 5.3L. Whenever I come to stop after driving, the engine doesn't idle smooth. Well, it does, for about 20 seconds. Silky smooth. After that, I can feel a faint shake through the floor. Before you say you don't feel it in your truck, put your left knee against the door trim while the engine is idling. Or look at the water in your plastic bottle in the cupholder.
The throttle body, MAF sensor and the engine's insides overall are clean. I wiped the intake pretty good through the TB opening while cleaning it. Smoked the engine multiple times through vacuum booster, no air leaks. I have AFM disabled through the stock tune (the only thing that is changed in the parameters). And there is a two-stage (sequential) catch can on the dirty driver's side.
I've been in several 5.3 trucks, and they all felt pretty much the same. Even the new gen DI engines have that faint shake.
So what is it? Why the engine is smooth for a while, and then shakes all of a sudden, and runs like that thereafter in idle?


'14 Chevrolet Tahoe
'15 Mazda CX-5
Re: Gm V8 shaking in idle [Re: yugrus] #4557569
10/28/17 06:47 PM
10/28/17 06:47 PM
Joined: Jan 2007
Posts: 17,501
Clovis, CA
Merkava_4 Offline
Merkava_4  Offline
Joined: Jan 2007
Posts: 17,501
Clovis, CA
How much mileage do you have on the upstream oxygen sensor(s) ?

I have the exact same problem and have been thinking of changing the upstream oh-two.

Re: Gm V8 shaking in idle [Re: yugrus] #4557613
10/28/17 07:17 PM
10/28/17 07:17 PM
Joined: May 2007
Posts: 939
IL
04SE Offline
04SE  Offline
Joined: May 2007
Posts: 939
IL
My 2014 Silverado does the same thing BUT only on 87. If I have E85 in the tank she is silky smooth at idle.

Idling in park I don't notice it as much. Idling at a stop light with my foot on the brake is when I notice it most.


Life's little problems can be solved with a shovel and silence.
Re: Gm V8 shaking in idle [Re: yugrus] #4557621
10/28/17 07:21 PM
10/28/17 07:21 PM
Joined: Feb 2013
Posts: 10,682
Phoenix, AZ
Nick1994 Offline
Nick1994  Offline
Joined: Feb 2013
Posts: 10,682
Phoenix, AZ
Does the shakiness change if you stop at a light and then put it in neutral? Could be motor mounts. Not necessarily bad motor mounts, just they might not be designed to make it so smooth you can balance a penny on the engine.


2015 Hyundai Sonata 2.4L 84k Mobil 1 AFE 0w30 & OEM
2000 Toyota Camry 2.2L 230k Valvoline 5w30 & Fram Ultra
1996 Jeep Cherokee 4.0L 147k Mobil 1 HM 10w40 & Fram Ultra
Re: Gm V8 shaking in idle [Re: yugrus] #4557636
10/28/17 07:30 PM
10/28/17 07:30 PM
Joined: Jan 2013
Posts: 1,841
Texas
WyrTwister Offline
WyrTwister  Offline
Joined: Jan 2013
Posts: 1,841
Texas
Find someone with an advanced code reader ( that can display real time data ) and that knows how to use it .

How are the spark plugs and the rest of the ignition system ?

Best of luck to you , :-)


Wyr
God bless
Re: Gm V8 shaking in idle [Re: yugrus] #4557642
10/28/17 07:37 PM
10/28/17 07:37 PM
Joined: Apr 2008
Posts: 498
Miami Beach
Tahoe4Life Offline
Tahoe4Life  Offline
Joined: Apr 2008
Posts: 498
Miami Beach
My 2016 Tahoe does it also. Not everyday though. Mostly in nasty gridlock. Does not bother me that much.


2016 Chevrolet Tahoe LT
Mobil 1 0w20 AFE or EP
AC Delco Filters
Re: Gm V8 shaking in idle [Re: yugrus] #4557716
10/28/17 08:27 PM
10/28/17 08:27 PM
Joined: Aug 2008
Posts: 18,326
Ontario, Canada
StevieC Offline
StevieC  Offline
Joined: Aug 2008
Posts: 18,326
Ontario, Canada
Could it be the IAC is a bit sticky and now allowing enough air in for a smooth idle?


'18 Highlander - AMSOIL SS 0w20 / ATF / Severe Gear
'06 Santa Fe - 535,000km AMSOIL SS 0w30 / ATF (R.I.P)
Re: Gm V8 shaking in idle [Re: yugrus] #4557784
10/28/17 09:18 PM
10/28/17 09:18 PM
Joined: Mar 2016
Posts: 19
NW Iowa
alchargo Offline
alchargo  Offline
Joined: Mar 2016
Posts: 19
NW Iowa
My '13 Avalanche does the exact same thing. As did my old Silverado 5.3. Seems to be a common issue. I think it comes with the ownership of a GM 5.3.

Re: Gm V8 shaking in idle [Re: yugrus] #4557888
10/28/17 10:51 PM
10/28/17 10:51 PM
Joined: Nov 2008
Posts: 9,033
Phoenix
dishdude Offline
dishdude  Offline
Joined: Nov 2008
Posts: 9,033
Phoenix
Could it be dropping the idle 50 or 100 RPM to save fuel?


2018 Challenger SRT
Re: Gm V8 shaking in idle [Re: yugrus] #4557897
10/28/17 10:57 PM
10/28/17 10:57 PM
Joined: Jul 2017
Posts: 309
PR CA, USA
2strokeNorthstar Offline
2strokeNorthstar  Offline
Joined: Jul 2017
Posts: 309
PR CA, USA
It's an emissions thing. They have to run them really lean at idle for smog reasons or so I was told. Had a 6.0L vortec that did it since new. The Drive-Thru was really annoying in that thing. Hate on Modular Fords all you want they are some smooth running motors.

Re: Gm V8 shaking in idle [Re: 2strokeNorthstar] #4557941
10/29/17 12:07 AM
10/29/17 12:07 AM
Joined: Jan 2007
Posts: 17,501
Clovis, CA
Merkava_4 Offline
Merkava_4  Offline
Joined: Jan 2007
Posts: 17,501
Clovis, CA
Originally Posted By: 2strokeNorthstar
It's an emissions thing. They have to run them really lean at idle for smog reasons or so I was told. Had a 6.0L vortec that did it since new. The Drive-Thru was really annoying in that thing. Hate on Modular Fords all you want they are some smooth running motors.


I always thought that an engine idling smoothy is an engine that's burning cleanly. No missfires.

Re: Gm V8 shaking in idle [Re: yugrus] #4557959
10/29/17 12:46 AM
10/29/17 12:46 AM
Joined: Apr 2004
Posts: 439
ON, Canada
yugrus Offline OP
yugrus  Offline OP
Joined: Apr 2004
Posts: 439
ON, Canada
Ok. Oxygen sensors are original, that makes it three years, pretty much brand new.
No E85 available here in Ontario where I am. Tried Shell 97, no ethanol, the truck didn't see the difference at all. Still shakes in idle.
Putting it in neutral doesn't make huge difference. Still shakes. Checked motor mounts for the torque twist, all solid.
I'very got Tech2,not sure what is more advanced reader there is... I didn't see anything out of order regarding fuel trim or air, idle or driving.
IAC- can't be sticky throttle plate, as I cleaned everything pretty good, including the shaft. It didn't make a difference anyway.
Gotta check actual injector timing when it starts happening. If they trim it significantly after idling for a while, will talk to Diablo to make some adjustments to the stock tune... I bet they know about the issue anyway...
I conclude that GM is doing it for emissions, as most owners would not notice that faint shake anyway. If I find a solution, I'll post it here.


'14 Chevrolet Tahoe
'15 Mazda CX-5
Re: Gm V8 shaking in idle [Re: yugrus] #4557974
10/29/17 01:06 AM
10/29/17 01:06 AM
Joined: May 2012
Posts: 5,363
Fort Lauderdale, FL
DoubleWasp Offline
DoubleWasp  Offline
Joined: May 2012
Posts: 5,363
Fort Lauderdale, FL
Shell 97 with no ethanol? I'm moving to Canada! thumbsup

This really seems to be a GM V8 thing. Got 3 NPR HDs with LS based engines, and the vibe is something they just do. Never thought about it, because they have a job to do, and I could care less about NVH, but it's something I might start investigating for the H of it.

On the other hand, I've had and come across a lot of silky big blocks.


07 Lincoln Navigator M1 0w-40/FU
68 Charger R/T / Supercharged 440 VR1/DBL7349
07 Ram 3500 4x4 / Cummins 6.7 /DBL7349
17 Maserati GranTurismo Cabrio
Re: Gm V8 shaking in idle [Re: yugrus] #4558279
10/29/17 10:45 AM
10/29/17 10:45 AM
Joined: Jan 2013
Posts: 1,841
Texas
WyrTwister Offline
WyrTwister  Offline
Joined: Jan 2013
Posts: 1,841
Texas
For what it may or may not be worth , the company 2008 Chevy Silverado , I think has the 4.8l LS engine . 160,000 miles , still has the OEM spark plugs . Purrs along at idle , on E10 .

Best of luck , :-)
Wyr
God bless


Wyr
God bless
Re: Gm V8 shaking in idle [Re: yugrus] #4558718
10/29/17 07:56 PM
10/29/17 07:56 PM
Joined: Feb 2011
Posts: 6,718
Hudson, NH
LeakySeals Offline
LeakySeals  Offline
Joined: Feb 2011
Posts: 6,718
Hudson, NH
I've been complaining about a strange idle in my GM 6.0 for the past 3 years I've owned it. Not always there, but some days I feel it sitting at a light. Best way to describe it is an electrical pulse. I've changed a ton of stuff. Its not vacuum. Not knock sensors. Not the TB. Not the plugs, coils. Not the catalyst. Transmission mount really helped a lot. Motor mount on drivers side should be replaced, feel it a little in the wheel. Can't see the engine shaking. But if you put your hand on the engine you feel it. A vibration that doesn't feel like a traditional ruff idle. Does not feel or act like a skip. Something electrical. Could be the lean at idle thing cause replacing the knock sensors reduced the frequency. And on cooler days doesn't happen. I've spent enough trying to fix the idle. Now its gonna be the insulation between me and the engine. Rubber mounts. I can't feel it as much with M1 5w30 as I can with other oils. Why who knows


06 Escalade 6.0L LQ9 AWD 165k M1 5w30
03 Maxima 3.5L POS 152k ST HM 10w30
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