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Showing results for tags 'preignition'.
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So, I've had this truck about 15 months. I bought it used from Carmax and ran 87 octane for the first year or so. I noticed that I got a good bit of engine pinging. It's would get worse under load or in hot weather. And during that year I always felt like the truck was a bit of a dog. In January, I'd had enough and bumped up to 91 octane for a couple months. It got much better but didn't quite go away. About 3 or 4 tanks ago, I switched to 93 octane (premium, in my area) and I don't think I've heard it ping once. The mileage hasn't changed (unsurprisingly), but the truck just feels "peppy." The throttle response is massively improved and it's a much better driving vehicle. I think the best way I can describe it is that it's no longer lazy. I mean, it's not a sports car, but it no longer needs a few seconds to get it to accelerate. I know the instant response to that is "it's all in your head" but my wife who has no idea (read: doesn't care) what's been going on commented the other day that I haven't complained about the truck's performance lately. I'm not excited about having to feed this beast premium, but if I don't I'm afraid it's going to tear itself up. Also, I haven't changed gas stations through this time and the ones I use are busy, top-tier locations so I'm not thinking the quality of the gas is involved. I'm thinking the truck was tuned by the previous owner. I'm going to ask about that at my next service visit, but I don't expect they'll tell me anything. Is there a way I can verify if the truck is on the stock tune? Also, has anyone else had a similar experience?
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.