issue 2014 rough engine idle

[Jesse Davidson]

http://www.autoguide.com/auto-news/2016/03/the-mysterious-chevy-shake-is-affecting-pickup-trucks-now-too.html

 

share share share!

[HondaHawkGT]

Meh nothing new really. Doesn't mention anything about solutions for idle vibrations that some guys here have. Seems like the driveshaft/pinion angles are the biggest source of vibrations. Too bad anyone with aftermarket anything will face scrutiny over mods that could cause a vibration sensation.

[fondupot]

My idle vibration went away after I had my tuner raise idle RPM from 500 to 600. Now it idles smooth as glass.

 

GM has the ability to do this. Why they don't is beyond me.

[rilcoat]

I have a 2015 Silverado 5.3 and was wondering if anyone has the issue of being a really bad rough idle when cold.

 

Mine idles really rough when cold, and once it reaches operating temp it seems to idle around 480-500 rpms with foot on brake and still idles rough at the lights.

 

Dealer says it's normal for rough cold idle and when hot no real answer other than wait for first oil change.

 

My other 2015 GM never idled rough

[ic3man5]

I have a 2015 Silverado 5.3 and was wondering if anyone has the issue of being a really bad rough idle when cold.

 

Mine idles really rough when cold, and once it reaches operating temp it seems to idle around 480-500 rpms with foot on brake and still idles rough at the lights.

 

Dealer says it's normal for rough cold idle and when hot no real answer other than wait for first oil change.

 

My other 2015 GM never idled rough

 

GM (probably for emission reasons) set the idle to 500 at 210F when in Drive/Reverse. Park/Neutral are 600. While its warming up it progressively drops to 500, if you lowered the T-Stat to I'd say like 180 it would probably idle around 550-600 but I'm convinced it also runs rich as hell when not at 210F (which is why I get extremely poor gas mileage below 40F). Mine is bumped up to 650 to get rid of all the roughness but while warming up it still has a bit of a shake.

[rilcoat]

ic3man5, on 11 Apr 2016 - 7:22 PM, said:

 

GM (probably for emission reasons) set the idle to 500 at 210F when in Drive/Reverse. Park/Neutral are 600. While its warming up it progressively drops to 500, if you lowered the T-Stat to I'd say like 180 it would probably idle around 550-600 but I'm convinced it also runs rich as hell when not at 210F (which is why I get extremely poor gas mileage below 40F). Mine is bumped up to 650 to get rid of all the roughness but while warming up it still has a bit of a shake.

I take it you bumped your up with a tuner?

[BigBadSierra]

 

GM (probably for emission reasons) set the idle to 500 at 210F when in Drive/Reverse. Park/Neutral are 600. While its warming up it progressively drops to 500, if you lowered the T-Stat to I'd say like 180 it would probably idle around 550-600 but I'm convinced it also runs rich as hell when not at 210F (which is why I get extremely poor gas mileage below 40F). Mine is bumped up to 650 to get rid of all the roughness but while warming up it still has a bit of a shake.

 

The Direct injected engines " injectors" work better at a higher heat. GM is running all of the DI engines in all of their model lines at or around 210. This includes the 4 and 6 cyl engines.

 

I read exactly why somewhere but can remember where or I would share the link. It was done to get the best performance out of the DI system though.

[BigBadSierra]

I have a 2015 Silverado 5.3 and was wondering if anyone has the issue of being a really bad rough idle when cold.

 

Mine idles really rough when cold, and once it reaches operating temp it seems to idle around 480-500 rpms with foot on brake and still idles rough at the lights.

 

Dealer says it's normal for rough cold idle and when hot no real answer other than wait for first oil change.

 

My other 2015 GM never idled rough

 

I just shot a can of CRC GDI cleaner though my truck and it idles smooth as new again.

[Jesse Davidson]

 

I just shot a can of CRC GDI cleaner though my truck and it idles smooth as new again.

mine never idled smooth

[Jesse Davidson]

Ok, I just picked my truck up and have a good amount of info to post for everyone.I will cover the repair attempts first, then at the bottom address more information I got from the foreman, so bear with me.

 

Vibration:

On the original pico-scope test, my truck registered 27 milli G's on a T1 (which is parts of the vehicle that rotate at tire speed). The GM threshold spec is 22 milli G's. So as it turns out, I really did have a bad tire, not by the RFB, (RFB measures the stiffness of the sidewall), but tread wise. When it was on the machine, the tire itself had lateral movement (lateral runout), so it was a manufacturing issue, and it was replaced.

 

On the second test, after getting the new tire, the truck registered 16 milli G's for the T1, although they did admit and put in writing on the service documents that it does increase in severity as the truck gets driven. Before even getting my keys, the Shop Foreman told me that I will still feel the vibration, it just won't be quite as bad. Specifically, he said that with a reading in the teens on the pico, you will still feel it, however GM doesn't consider below 22 milli G's a problem, yet the foreman agrees that feeling any vibration in a vehicle this expensive is ridiculous, and he would be as pissed as we all are.

 

As for my own road test, I was pissed off and just made the short back road trip back to my house, and didn't hit any highways. I can say however that atleast on the back roads, there is little if any improvement, possibly even slightly worse, I need to take a longer drive to rally figure it out. I will hit the highways over the next few days and report if I think it is any better then.

 

Radio:

As for the radio issue, they performed PI1374F, which is actually directed to the 2014 MY trucks that also have issues with fading radios'. This did help slightly with how the highs get lost, in the sense that it isn't quite as pronounced, but it still happens. In addition, the radio now makes an intermittent buzzing sound and gets more static than it ever used to. Thinking that maybe they took the unit out, and a connection came loose. I called them when I got home to ask if they did, and they said no, so the truck is going back on Tuesday regardless of the severity of the vibration on the highway.

 

GM Trade in:

So just for kicks, after they gave me the paperwork and said it was all fixed, I asked what they could do for me on getting me into a '16 Sierra, since my truck is now all set.... They offered 28k for my truck, and thats from a GM dealer... so even GM wont pay what the their own trucks are supposed to be worth, smdh.

 

Well maybe they can fix your radio.

Nope

 

More Info:

Jesse D, any chance you can bring this up with your newly found GM friends? See if they could tell from PICO the difference between a tire out of round or a hub out of round? If the hubs are made overseas, they may not be heat treated correctly if at all and distorting.

No, the Picoscope can not tell the difference between the tire and the hub, the hub spins at tire speed and is shown as part of a T1 Vibe, it is up to the tech to figure what part could be causing the vibration.

 

So as we know, GM lowered their RFB spec, industry standard is 30 lbs, GM has decided theirs is now 25 lbs, allegedly to try to help the vibration we all have. Mine all registered 16lbs or lower.

 

GM has set their threshold PICO number to 22 milli G's, yet the vibration will still be felt even lower than that, like my truck for example at 16 milli G's

 

GM currently has 37 PI's in their system all related to attempting to fix vibration in their SUV' and Truck' (the foreman showed me the system on the computer)

 

Some people like myself have noticed that we have paid for upgraded A/T tires, yet got Wrangler SRA' tires, a highway all season tire. Per the shop foreman, GM decided that the Wrangler SRA is an A/T tire, even though industry says its not, and neither does GoodYear for that matter. (the foreman agrees that the SRA is not an A/T tire).

 

Both the shop foreman and the sales manager I spoke with suggested continually calling GM to complain and say you're very unhappy with the trucks, and to try to make as much noise about the problems as we can.

 

NEW RECALL:

In case anyone hasn't heard it yet, GM is now recalling 1.04 million 2014 and 2015 Pickups because of faulty seat belts. check your vins everyone.

[Jsdirt]

Good info, Jesse - thanks for posting.

 

I had no idea things have advanced to the point of measuring vibration. I've got to do some reading on milli G's and RFB - never heard of either.

 

I'm still dumbfounded that they still produce vehicles like this. How the hell can this be missed? Do they even test anything they build before it rolls out the door? Friggin amazing ...

[Jesse Davidson]

Good info, Jesse - thanks for posting.

 

I had no idea things have advanced to the point of measuring vibration. I've got to do some reading on milli G's and RFB - never heard of either.

 

I'm still dumbfounded that they still produce vehicles like this. How the hell can this be missed? Do they even test anything they build before it rolls out the door? Friggin amazing ...

RFB is Road Force Balancing, its basically the new standard/ method of balancing a tire. You really need to have a tech who knows what the h*ll they are doing with the machine though, otherwise it can make anything vibrate.

 

For milli G's, think of G-force like in a fighter jet. milli G's is (1/1000) of a G-force. For my truck it is lateral.

 

The Pico scope measures in both the vertical and lateral directions, and reads out in a graph and chart on a laptop they bring with them.

[Jsdirt]

Ahh, road force - that I've heard of. Been a long day - I couldn't make the connection, lol.

 

Thanks for the additional info. Interesting! I could've used equipment like that back in the day. I wonder what that PICO would've registered when I first got my '72 El Camino, and it had been running on u-joints with no needle bearings in them for almost 10k miles. Over 60 you couldn't even see straight, HAHAHA!

[Ryan11405]

I'm a long time lurker.. first GM was a 2004 GMC Sierra CC Z71 4wd, bought it in 2005 with 27k miles, traded in Feb. 2015 with 210k on the clock. Family had two 2000 vehicles, Chevy silverado and GMC Yukon XL that lasted 265k+. Never seen a vibration at idle like the 2014 Chevy Silverado CC 5.3 2LT Z71 2wd I just bought. it idles in drive just under 500 rpm, has a big vibration in drive at idle with brake applied. First noticed it on the test drive then again in town after a long highway drive.

 

Got the wife to sit in the drivers seat and shift it around, and I noticed that there was no vibration at all until she shifted into drive. When she did, the motor shifted/flexed about 2cm clockwise (to the right side of the truck) and the truck was vibrating bad. No shift/flex in other gears. Wonder if the issue is just spongy motor mounts? It drives fine, although at 76-78 mph it vibrates like crazy (off and on) but I think that problem is suspension.

[Jsdirt]

If anything spongy motor mounts will isolate any engine vibration ... but the mounts will be junk sooner than normal. Just the laws of physics.

 

I remember the engine in our '00 Jimmy moved about 6" under load with 106k on the clock. Parted that POS out at 146k, but that's another story for another time ...

 

Seems to be the way of the world today. Everything is sold at maximum cost, with maximum cost of ownership, with the least reliability, cheapest of cheap parts, and non-existent quality control.