Hello All,
New to forum and looking for some advice....
I have a 2018 Sierra 5.3 with the 8-speed, 63,500 miles. About a month ago, while driving around at light-medium throttle I get an intermittent shudder thru the truck that feels very much like driving over a rumble strip. Sometimes it lasts for only ~0.5s, sometimes it may last 3 to 5 seconds, the longer instances are less common. Overall it only happens occasionally...maybe once every 3-5 min on average, but sometimes I'll get a few distinct occurrences back to back to back.
The part that is curious, is that even when stopped (at a red light or stop sign)...I get a very brief shudder that causes the engine RPM to drop to ~450, but only lasts for less than 0.5 second and is immediately recovered to the normal 500rpm at idle and idles dead smooth from there. On average this may happen only a few times when stopped at the average red light.
I took it into a local dealer and after two days with the truck they came back with a diagnosis of a misfire on cylinder #2 and recommend replacing plugs/wires. There is/was no CEL then or now. I replaced all 8 plugs (old ones looked good to me), the wire and ignition coil for cylinder #2. The problem still persists.
3 months ago (before I had any of these problems) I had the intake cleaning service (including throttle body) performed at the end of my CPO warranty. The truck ran so smooth that sitting at idle you had to look at the tach to now it was on.
I have logged some data in my scan tool and will post once I find the cable to download it to the computer.
Thanks for any help/advice...
- Marco
Hello All, New to forum and looking for some advice.... I have a 2018 Sierra 5.3 with the 8-speed, 63,500 miles. About a month ago, while driving around at light-medium throttle I get an intermittent shudder thru the truck that feels very much like driving over a rumble strip. Sometimes it lasts for only ~0.5s, sometimes it may last 3 to 5 seconds, the longer instances are less common. Overall it only happens occasionally...maybe once every 3-5 min on average, but sometimes I'll get a few distinct occurrences back to back to back. The part that is curious, is that even when stopped (at a red light or stop sign)...I get a very brief shudder that causes the engine RPM to drop to ~450, but only lasts for less than 0.5 second and is immediately recovered to the normal 500rpm at idle and idles dead smooth from there. On average this may happen only a few times when stopped at the average red light. I took it into a local dealer and after two days with the truck they came back with a diagnosis of a misfire on cylinder #2 and recommend replacing plugs/wires. There is/was no CEL then or now. I replaced all 8 plugs (old ones looked good to me), the wire and ignition coil for cylinder #2. The problem still persists. 3 months ago (before I had any of these problems) I had the intake cleaning service (including throttle body) performed at the end of my CPO warranty. The truck ran so smooth that sitting at idle you had to look at the tach to now it was on. I have logged some data in my scan tool and will post once I find the cable to download it to the computer. Thanks for any help/advice... - Marco