2014 Sierra, 5.3L, 2WD, -- Preignition, Detonation, Knock & Ping,

[cklein7385]

My 2014 Sierra Crew Cab, 2WD with the 5.3L has a pre-ignition issue (detonating, knocking & pinging, rattling, dieseling, etc. -- pick the term you want to use). Has anybody else had this problem?

 

This occurs regularly (but not all of the time) at 1/2 to 3/4 throttle while accelerating. It's not something that happens all of the time so it is tough to pin down exact conditions to duplicate the issue. Of course my local GMC Service Department "can not duplicate" the problem. I understand that most people (and I suspect most of the mechanics at the dealership) have no idea what pre-ignition sounds like, and since it is not setting any trouble code, I can't get any traction on getting the problem fixed or even acknowledged. Since the problem seems to be intermittent I've gone so far as to document the dates and times of the issues and ask the dealership to pull the vehicle run history and see what was going on during those times. This has fallen on deaf ears as the service department is unwilling to take this information in an attempt to identify the problem. The ECM has been re-flashed several times without any improvement.

 

On several occasions I have dropped the truck off at the dealership, given them a punch list of things to do/fix (including looking into the pre-ignition problem) and they always come back with "unable to duplicate". I have contacted GM Customer Service and have a Case Number, but that has gotten me nowhere as all they tell me to do is to take it to the dealership. I plea my case that my local dealership does not seem very interested in fixing the problem and I even stopped by the dealership when the problem was occurring to take a the service manager for a ride so he can hear the "knocking and pinging". The manager stated that he was unable to ride with me because he was the only service writer available at the time and I would need to come back. However, before he finished telling me to come back, another service writer showed up at the counter, but the manager would still not go on a drive with me to identify the problem.

 

I'm not sure what the action plan would be if a service writer or technician ever "hears" the problem, but my past experience tells me they will still not acknowledge the issue, or state that the noise is from some other component that is working "as intended". An engine that spends its life with a pre-ignition problem is not a high mileage engine. I'm sure it will make it through the powertrain warranty period before it kills itself by way of detonation, and that concerns me.

 

Does anybody have any suggestions on getting this moved up the ladder in GM Customer Service where I can actually get GM to look into the problem?

 

Thanks.

[ifixedit]

You may just be having more of a where you are buying your fuel from problem. I've noticed rather varying grades of gasoline depending on where I buy. Most 87 - 88 octane (or some advertised as premium for cheap) especially from the cheapo discount stations is about as good these days as watered down cat pee, run it in your lawnmower but not your truck. On most of this crap my truck pings like crazy, from a few other stations the 87 octane causes no problems at all or very slight pinging at times, but it also depends on the season and the blend being sold at the time. I'd suggest taking a trip to another gas station first. Drop a tank of premium (91 to 93 octane) in it from a busy, national brand station and see if your problem goes away. It's tempting with the cheap gas prices right now, but I generally use ONLY mid grade and up and never a problem.

[cklein7385]

Thanks ifixedit, I appreciate your response.

 

I typically only use busy, national brand stations and switch between 3-5 different stations depending on when I decide to fill up. I understand that summer/winter blends are different and differences in ethanol content and that some brands and storage tanks just aren't very good. What is frustrating is that I have yet to find any 87 octane fuel anywhere that won't cause detonation in my truck. When I use 89 octane and higher it will eliminate the problem. I don't understand why the engine management software won't simply retard the timing enough and eliminate the knock (like it does when you put 87 octane in a car that "requires" 91). I'd rather have the loss of power from the retarded timing than the eventual death of the top connecting rod bearings with continuous detonation.

 

With gas prices like they are now, I don't mind using 89 (or higher) octane in an effort to keep from killing my engine with detonation, if gas prices go back up, then that's a different story. My bigger problem is that GM recommends 87 octane (per the owners manual), the truck won't run correctly on 87 octane, and they won't make any effort to address the problem. If I continually run 89 and higher octane, then there is no chance that a GM service tech will ever identify the problem in order to address it, because with higher octane the detonation stops. The 89 octane is just a Band-Aid that treats the symptom, not the problem. I would like for GM to fix the problem.

 

Unfortunately I have had several problem with the truck and my local dealership has ignored them. I have been able to diagnose some of these problems myself, then prove to the dealership that the problem(s) exist (I shouldn't have to do this on a new truck that's under warranty). The detonation problem (and the rough idle problem and the low idle speed problem and occasional "dip" in idle speed while stopped) are problems that I can not address in my garage and GM is not interested in fixing anything.

[Bassinz71]

I have a similar problem with my 2014 (30k miles). I noticed it was making a noise with 87 octane when it had around 15k miles on it so I bumped it up to mid grade and even 93 octane and it still does it. I had it at the deal for a week and they could not duplicate so I took them on two ride alongs and they acknowledge the issue but had no suggestions other than run 87 in it from a top tier station (I have only run top tier since I purchased it) saying that the higher grades have additives that would not burn off and could be causing the noise. I thought that was BS but I ran a couple of tanks of 87 through it after they did a 'chemical clean' and noticed no difference at all. My brother has the same truck with no issues and runs worse gas due to his location. I haven't had time to contact GM but I will soon hoping they can resolve the issue.

 

The dealer contacted them looking for advice and GM said to run the clean but clearly that did not fix the issue. What is frustrating is the dealer just says I have 100k of warranty to if it blows up then no big deal! I want the issue fixed because I know at 110k its probably going to blow.

 

Anyways, I will update if GM or the dealer can solve my problem but I don't see that happening.

 

Good luck and let me know how it turns out for you on your end.

[HondaHawkGT]

87 octane ethanol blend is barely even gas. The stuff goes flat after a month or two. There are actually rumors about the fed mandating a higher octane standard. All auto manufacturers are pushing the limits of what they can do with the glorified piss they call 87. 89 or 90 octane might be the new regular unleaded down the road.

 

Based on what Lingenfelter found during their initial evaluation of the new 5.3, GM designed the engine to just barely get by on 87. A lot of tuners that have looked at datalogs of stock 5.3's have said that owners should run a minimum of 89. GM is relying on the knock sensors and ECU to make 87 work.

 

You either have bad gasoline or perhaps one of the knock sensors is acting up. You could also have false knock that's causing the ECU to freak out - loose exhaust components, loose engine/trans mount, etc.

 

I only run 91 since 89 isn't as common. My truck seems to run shitty on 87 too.

[cklein7385]

I appreciate everyone's comments. I guess I now know this isn't just my truck.

 

I don't disagree that 87 octane is probably pretty weak based on the compression ratio of the engines, but if the engines won't run correctly on typical 87 octane fuel, then the trucks shouldn't be sold with a recommendation by GM to run 87 octane. That might be why the factory powertrain warranty has been reduced to 60,000 miles on the new trucks. Maybe GM has realized the engines won't live 100,000 miles with the detonation. The knock sensor and ECM should be able to retard the timing enough to stop the detonation instead of the eventual death of the engine.

[bagger97]

Wow, I had to go look at the web site for the warranty change you said. That sucks big time...5/60k power train is not enough. Bad idea GM. Glad I got a 2015

[HondaHawkGT]

Yeah that was a pretty disappointing move by GM. I think GM dropped to a 5yr/60k purely for profit motivated reasons. All their main competitors have been 5/60k or less this entire time. Fiat-Chrysler was the only other player left with a 5/100k and that didn't last long once GM made the announcement. Considering their reliability ranking, I'm not sure it was the best move by FCA.