Hi there, I just bought my first 100-series two weeks ago and am having some issues.
I’m trying to fix a CEL that comes on (and sometimes flashes) at about 75mph or under heavy load. The truck feels smooth and I don't feel any power loss. It idles normally, and the only vibration on the road is what I believe to be a tire alignment issue around 55mph. I don't drive on the interstate often where I live, but when I hopped on this past week, I turned around quickly when the CEL began to flash. The flashing stopped around 55mph, then came back and flashed again at about 65mph as I merged off. I pulled into an AutoZone and scanned three pending codes: P0300, P0305, and P0308. Prior to this, I had been driving around town at normal speeds peaking around 65mph and had no issues with power, knocking, or vibrating.
I parked the truck and just started working on it today. My dad has a scanner, so we cleared the codes to diagnose the issue. We started by recreating the conditions (load, AC, etc.) to trip the code, then we swapped the plugs and coils for 5 and 8, but the codes remained. Next, we swapped injectors 6 and 8 as they were easier to access, but the issue stayed the same.
Since it appears to be isolated to cylinders 5 and 8 and doesn't follow the parts, I’m looking for next steps. Has anyone dealt with this specific misfire on 5 and 8?
Thanks!
I’m trying to fix a CEL that comes on (and sometimes flashes) at about 75mph or under heavy load. The truck feels smooth and I don't feel any power loss. It idles normally, and the only vibration on the road is what I believe to be a tire alignment issue around 55mph. I don't drive on the interstate often where I live, but when I hopped on this past week, I turned around quickly when the CEL began to flash. The flashing stopped around 55mph, then came back and flashed again at about 65mph as I merged off. I pulled into an AutoZone and scanned three pending codes: P0300, P0305, and P0308. Prior to this, I had been driving around town at normal speeds peaking around 65mph and had no issues with power, knocking, or vibrating.
I parked the truck and just started working on it today. My dad has a scanner, so we cleared the codes to diagnose the issue. We started by recreating the conditions (load, AC, etc.) to trip the code, then we swapped the plugs and coils for 5 and 8, but the codes remained. Next, we swapped injectors 6 and 8 as they were easier to access, but the issue stayed the same.
Since it appears to be isolated to cylinders 5 and 8 and doesn't follow the parts, I’m looking for next steps. Has anyone dealt with this specific misfire on 5 and 8?
Thanks!