2014 Sierra Denali 5.3L knocking & drive line slop in traffic

[glocklt4]

I have tried searching everywhere for someone else with the same issues as me, but not having much luck. And yes, I'm trying to get it back in the dealer but have been crazy busy and out of the country a lot. As someone who works on cars relatively frequently, I'm stumped.

 

So, 2014 Sierra Denali w/ 5.3L 12.5k miles. I have tried a broad range of 87 octane gasolines (Chevron, Exxon, Quicktrip, Kroger, RaceTrac, etc...) but continue to get significant knocking under load (3k+ rpm w/ 40%+ throttle I'd say). Even with 89oct I still get some, but not as much. 93oct is the only way to prevent it at all. When towing my boat it's worse due to even bigger load. This is unacceptable for a n/a engine...

 

I realize the main difference to this and any other vehicle I've worked on is direction injection, and I can't help but think there is something going on there. I brought this up with the dealer about 6mo ago when I took it in for a squeak on the exhaust plate actuator controlled by the Cyclinder Deactivation (also new to me), and of course the response was "fill it up with a different tank of gas". Well I've just been putting 89 in it since then to avoid most the knocking, but I'm tired of the additional cost I shouldn't have to be spending.

 

Other issue is that this transmission sucks in stop-go traffic. If you quickly (even midly) go from brake to gas, or even coasting to gas - there is major slop in the transmission or drive line to where 50% of the time there is a significant bang that is heard and felt as well. I don't think it's a transmission issue itself as it seems to shift quick and the bang is after the shift happens. I've been lucky to never have U-joints go out on a vehicle, but I'd think 6mo and 5k miles would have broken the rest of it if that was the problem.

 

I love this truck otherwise, but these two things are just unacceptable for a new luxury truck. Also I asked a buddy with a 2015 Sierra Denali and he doesn't have these issues at all, and even runs 87oct from Kroger (obviously not top quality gas, but I've traditionally used it for years now for $1/gal off everytime with fuel points).

[glocklt4]

Haha yeah - good luck getting 40 years out of a vehicle these days!

[Jsdirt]

GM's explanation fails to explain why cars and trucks built for the last 100 years haven't done this - it's only ones built in the 21st century. HMMM ....

 

Guess drivelines have been lasting too long for the new beancounters, so something had to be done about that ...

 

My '86 Grand Marquis, that will have been in my possession for 13 years this January, is nudging 227k miles ... and the driveline doesn't make a peep, even if you TRY to! Only thing I've done to the nearly 30 year old rear end is new axle seals, and Amsoil Severe Gear. Never touched the transmission, aside from a filter change 10 years ago. Still works perfectly.

[Doug_Scott]

Engine should have knock sensors on it, and should be able to control the pinging. It also should be easy enough for the technician to see what is going on in regards to the pinging. They should be able to record a session of you driving around getting the engine to ping.

 

Are you buying your fuel at the same physical gas station as your buddy? Same brand is meaningless given that the two stations may be getting their fuel from two different refineries, and may even be getting two different sources of fuel. No idea what it is like in the states, but around here it is not uncommon to see a fuel truck drop fuel at a Shell station, then drive 2 miles down the road to an Esso station and drop fuel there as well.

 

I would expect direct injection to be a giant step forward in engine controls. They have been able to raise compression ratios due to having direct injection now. What does the owners manual say in regards to what fuel to use?

[Jsdirt]

Sounds like you've got a clone of my truck 7 model-years later! Mine does, and has done the EXACT same things since it was brand new. Towing heavy loads, the engine sounds like it will grenade! I'm talking SEVERE detonation. Not good.

 

I've just got used to paying an additional .30-.50 cents per gallon for gasoline over the years.

 

As far as the driveline slop goes, I believe there's some "slop" in GM's quality control the past 19 years. Mine makes a loud clunk at light throttle upshifts & downshifts.

 

 

I've got a 2k mile round-trip road trip coming up - wish me luck!

[Doug_Scott]

The gasoline here in MA is cut so heavily with ethanol - that might be a contributing factor as well. Some stations are worse than others, but I find very few obey the posted "10% Ethanol Content" signs on every pump. Quite a few stations are pushing 20%! We're getting ripped off left and right. The state doesn't care, because 3 mpg times 4 million registered vehicles all paying road tax more often than they should be, sits very well with them.

 

People would stage an armed revolt if anyone cut their liquor or medication by 20% ... but for some reason, their ok with that happening to their fuel. Kills mileage & power too. I pick up 2-3 MPG whenever I find ethanol free gasoline out of state, and the truck feels like it gained 40 RWHP.

 

I was an idiot buying this truck. Don't know what the hell I was thinking. Was working every waking moment of my life at the time, and figured I'd buy new so I "wouldn't have to work on it". LOL what a joke that turned out to be. Since I spent so much money on it, I figure I need to get at least 40 years out of this thing. Fat chance with electronics, & cheaped-out materials! Had I used my head, I'd have taken the $30k and done a total restoration of my '72 El Camino, and bought a winter beater for winter time. Live and learn ...

 

E85 has a high octane rating, so, I would think that E10 would have a higher octane rating that straight regular(assuming the base fuel in both blends are the same to start with). I know that around here they used ethanol to get the 94 octane at Sunoco stations in 98-05. I ran a couple of tanks of that in my GTP with a smaller pulley on the supercharger. The big effect I saw was a big drop in economy. I think they were using 15% then. The unadulterated high octane fuel was 91 octane then.

[glocklt4]

Dealership says that they were able to produce the pinging under the right conditions but that the knock sensors should retard the timing to take care of it. I'm not too happy with this result. They basically said to run higher octane in it, when owners manual says run 87 or lowest available in area. That means the truck will cost more to run in order to avoid damaging the engine. They said that my oil change was over the recommended timeframe even though I'm following the computer's recommendations, and said that it's possible the oil being dirty could cause an increased chance of pinging. I don't buy that, but we'll see since they did another change for me. Only reasons I know of for pinging are bad gas that is lower octane than rated, carbon deposits causing either higher compression or hot spots in cylinder, bad fuel mixture (too lean I believe), or bad/wrong plugs.

 

As for the driveline slop, they also said this was normal. Very frustrating...

 

Suggestions at this point? I feel gypped since the truck cannot run as advertised on 87octane without causing longterm damage.

[newdude]

On the clunk:

 

Some customers of vehicles equipped with automatic transmissions may comment that the vehicle exhibits a clunk noise when shifting between Park and Drive, Park and Reverse, or Drive and Reverse. Similarly, customers of vehicles equipped with automatic or manual transmissions may comment that the vehicle exhibits a clunk noise while driving when the accelerator is quickly depressed and then released. Tipping into the throttle after deceleration can also result in some level of clunk as the driveline is loaded in one direction (coast) then with throttle reapply the driveline gets loaded in the opposite direction (drive). On manual transmission vehicles depressing the clutch while in a deceleration immediately releases load on the driveline and may produce a clunk noise as the driveline unloads.

Note: Compare this complaint vehicle to a like vehicle. If the results are the same, this is a normal condition. For additional diagnostic information, refer to the appropriate Service information.

Whenever there are two or more gears interacting with one another, there must be a certain amount of clearance between those gears in order for the gears to operate properly. This clearance or freeplay (also known as lash) can translate into a clunk noise whenever the gear is loaded and unloaded quickly, or whenever the direction of rotation is reversed. The more gears you have in a system, the more freeplay the total system will have.

The clunk noise that owners sometimes hear may be the result of a buildup of freeplay (lash) between the components in the driveline.

For example, the potential for a driveline clunk would be greater in a 4-wheel drive or all-wheel drive vehicle than a 2-wheel drive vehicle. This is because in addition to the freeplay from the rear axle gears, the universal joints, and the transmission (common to both vehicles), the 4-wheel drive transfer case gears (and their associated clearances) add additional freeplay to the driveline.

In service, dealers are discouraged from attempting to repair driveline clunk conditions for the following reasons:

• Comments of driveline clunk are almost never the result of one individual component with excessive lash, but rather the result of the added affect of freeplay (or lash) present in all of the driveline components.

  Because all of the components in the driveline have a certain amount of lash by design, changing driveline components may not result in a satisfactory lash reduction.

• While some owners may find the clunk noise objectionable, this will not adversely affect durability or performance.
• For additional diagnostic information, refer to the appropriate Service Information.

 

[glocklt4]

Engine should have knock sensors on it, and should be able to control the pinging. It also should be easy enough for the technician to see what is going on in regards to the pinging. They should be able to record a session of you driving around getting the engine to ping.

 

Are you buying your fuel at the same physical gas station as your buddy? Same brand is meaningless given that the two stations may be getting their fuel from two different refineries, and may even be getting two different sources of fuel. No idea what it is like in the states, but around here it is not uncommon to see a fuel truck drop fuel at a Shell station, then drive 2 miles down the road to an Esso station and drop fuel there as well.

 

I would expect direct injection to be a giant step forward in engine controls. They have been able to raise compression ratios due to having direct injection now. What does the owners manual say in regards to what fuel to use?

 

 

 

 

Agree to knock sensors and EMC/PMC monitoring. I'll have to see what they say. I did expect to see codes by now for the amount of knock I can get when running 87 and towing.

 

No, haven't been buying gas at same stations, however when I try many different gas stations all over town for a couple months and it always knocks on 87, less at 89 and none at 93, that's a pretty consistent result to me. The constant is the engine. Didn't know that the fuel trucks go to multiple locations actually, thanks for that info. I always assumed one truck went to one station and unloaded everything there.

 

Owners manual says 87: "For all vehicles except those with the 6.2L V8 engine, use regular unleaded gasoline with a posted octane rating of 87 or higher. If the octane rating is less than 87, an audible knocking noise may be heard. If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. If heavy knocking is GMC Sierra Owner Manual (GMNA-Localizing-U.S./Canada/Mexico- Black plate (71,1) 5853626) - 2014 - 1st crc - 3/7/13 Driving and Operating 9-71 heard when using a higher octane rated gasoline, the engine needs service."

[glocklt4]

Sounds like you've got a clone of my truck 7 model-years later! Mine does, and has done the EXACT same things since it was brand new. Towing heavy loads, the engine sounds like it will grenade! I'm talking SEVERE detonation. Not good.

 

I've just got used to paying an additional .30-.50 cents per gallon for gasoline over the years.

 

As far as the driveline slop goes, I believe there's some "slop" in GM's quality control the past 19 years. Mine makes a loud clunk at light throttle upshifts & downshifts.

 

 

I've got a 2k mile round-trip road trip coming up - wish me luck!

 

Well that's enouraging! not . I'm not going to put up with this for 7 years haha (either the engine knock or the drive line slop).

[Jsdirt]

Sorry to hear that. Par for the course today. They really don't build anything like they used to.

 

Your right on pinging - oil (or lack of) doesn't cause pinging - it will cause knocking, if let low enough. A totally different cause.

 

On something that new, and with computer controlled everything, I highly doubt there's any carbon deposits in there. My '00 4.3 with 146k miles on it had nearly SPOTLESS pistons when I yanked the heads. Just discoloration from heat.

[glocklt4]

Thought I'd provide an update here. Dropped the truck off at the dealership today and my service guy said I am about the 100th person he's heard of with the shift and driveline slop issues. He confirmed the bulletin above about how this is "normal", but I balked with him over this quite a bit. He said he is going to have his guys look at it regardless for me and see if it's any worse than the other cases they have seen. He said it is good to document it in case they end up doing a recall of some kind or things break down the line.

 

So the main thing they will be looking at is the pinging. Should have some additional info tomorrow afternoon hopefully.

[Jsdirt]

The gasoline here in MA is cut so heavily with ethanol - that might be a contributing factor as well. Some stations are worse than others, but I find very few obey the posted "10% Ethanol Content" signs on every pump. Quite a few stations are pushing 20%! We're getting ripped off left and right. The state doesn't care, because 3 mpg times 4 million registered vehicles all paying road tax more often than they should be, sits very well with them.

 

People would stage an armed revolt if anyone cut their liquor or medication by 20% ... but for some reason, their ok with that happening to their fuel. Kills mileage & power too. I pick up 2-3 MPG whenever I find ethanol free gasoline out of state, and the truck feels like it gained 40 RWHP.

 

I was an idiot buying this truck. Don't know what the hell I was thinking. Was working every waking moment of my life at the time, and figured I'd buy new so I "wouldn't have to work on it". LOL what a joke that turned out to be. Since I spent so much money on it, I figure I need to get at least 40 years out of this thing. Fat chance with electronics, & cheaped-out materials! Had I used my head, I'd have taken the $30k and done a total restoration of my '72 El Camino, and bought a winter beater for winter time. Live and learn ...

[Doug_Scott]

The knock sensors should be picking up the noise, and signalling the ECM to do something about it. Have to wonder if maybe GM is also playing with the ECM programming like VW has admitted to. Knock sensors on the pickup trucks with carbs would hear the ping and retard the timing pretty aggressively. You could take a small ball peen hammer and tap the block and see it change the timing. Pretty sure the Tech2 tool can also bring up detonation history. I think Justin at BlackBear could see it in a capture/log as well when he would tune for higer octane fuel.

Dealer was correct though, you want them to record that you reported the issue, and that they actually looked into it. Would be good if you could have them record it on the work order that they heard the ping that you complained about as well.

 

Not trying to be picky, but, I think the manual just says to "use a minimum of 87 octane fuel." There is nothing in the manual about using the lowest in your area. All they are saying is do not use anything less than 87 octane.

[glocklt4]

On the clunk:

 

 

Thanks for this info. That is pretty discouraging to read that they don't care! Surely this is going to end up causing damage to parts over the life of the truck... when the slop in the driveline hits resistance, that bang is stressing parts no matter what. Ugh...

 

One interesting quote: "The more gears you have in a system, the more freeplay the total system will have."

 

I went from a 4 gear Tahoe to this truck with 6 gears, so I can kind of understand that adding 50% more gears might end up with more play, however my Tahoe didn't have any except when shifting from park to reverse - but i find moving from park into any gear is acceptable to have some "lash" wind up. Not when driving though...