Knocking or banging under load
Thread Starter
Junior Member
Joined: Mar 2017
Posts: 22
Likes: 2
From: Hayesville, NC
Knocking or banging under load
My 2016 F-150 Platinum has 135K miles and had a major tune-up with plug changes about 2 years ago.
Last Monday, a week ago today, the engine starting missing as if one cylinder was not firing, but that stopped after about 30 seconds. Then there were some occasional but infrequent bangs or knocks under load, but most driving was fairly normal. The bangs were about 2 seconds apart, and there were never more than 3 or 4 in a row.
I drove lightly around town the next few days and the banging appeared just once or twice. On Thursday I took the truck to my dealer for a quick diagnostic check. There were no trouble codes and the check engine light was not on, and never had been during this problem. I asked if it was safe to take the truck on a 250 mile road trip on Friday. The dealer thought it was so and I did that. There were 2-3 bangs about 3-4 times on the way home while under load and cruise control going up a hill at about 65-70mph. Earlier in the day, there was a lot of 75-80mph cruising with no problems, but I never hit the gas hard.
Today I drove about 30 miles mostly at 55-60mph with no problems, using adaptive cruise control for most of that.
What could be causing this and how does it get diagnosed properly? The banging is similar to what I have had with rare odd transmission downshifts, but I have been watching and there were no gear changes associated with the banging.
Last Monday, a week ago today, the engine starting missing as if one cylinder was not firing, but that stopped after about 30 seconds. Then there were some occasional but infrequent bangs or knocks under load, but most driving was fairly normal. The bangs were about 2 seconds apart, and there were never more than 3 or 4 in a row.
I drove lightly around town the next few days and the banging appeared just once or twice. On Thursday I took the truck to my dealer for a quick diagnostic check. There were no trouble codes and the check engine light was not on, and never had been during this problem. I asked if it was safe to take the truck on a 250 mile road trip on Friday. The dealer thought it was so and I did that. There were 2-3 bangs about 3-4 times on the way home while under load and cruise control going up a hill at about 65-70mph. Earlier in the day, there was a lot of 75-80mph cruising with no problems, but I never hit the gas hard.
Today I drove about 30 miles mostly at 55-60mph with no problems, using adaptive cruise control for most of that.
What could be causing this and how does it get diagnosed properly? The banging is similar to what I have had with rare odd transmission downshifts, but I have been watching and there were no gear changes associated with the banging.
Thread Starter
Junior Member
Joined: Mar 2017
Posts: 22
Likes: 2
From: Hayesville, NC
Probably never. The truck gets regular dealer service and has had its major tune-ups, but I don’t recall ever seeing anything about transmission fluid.
The truck has to go in for a brake job next week, so I’ll add that.
The transmission has always had a quirk that no one could duplicate or fix. It happens only when I leave home on a cold day, and wouldn’t happen anywhere else. Living at the top of a steep hill, my first drive is always about 1/3 of a mile to the bottom without ever touching the gas except very lightly to start moving. By the bottom of the hill the truck is in third gear and usually won’t downshift when I stop. If I then start there is a huge bang when it downshifts under load. I avoid the problem by manually shifting into 1st and 2nd gear only for the downhill. After that, the fluid has moved and warmed up and the truck is fine.
The truck has to go in for a brake job next week, so I’ll add that.
The transmission has always had a quirk that no one could duplicate or fix. It happens only when I leave home on a cold day, and wouldn’t happen anywhere else. Living at the top of a steep hill, my first drive is always about 1/3 of a mile to the bottom without ever touching the gas except very lightly to start moving. By the bottom of the hill the truck is in third gear and usually won’t downshift when I stop. If I then start there is a huge bang when it downshifts under load. I avoid the problem by manually shifting into 1st and 2nd gear only for the downhill. After that, the fluid has moved and warmed up and the truck is fine.
5 Year Member
Joined: Feb 2020
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Probably never. The truck gets regular dealer service and has had its major tune-ups, but I don’t recall ever seeing anything about transmission fluid.
The truck has to go in for a brake job next week, so I’ll add that.
The transmission has always had a quirk that no one could duplicate or fix. It happens only when I leave home on a cold day, and wouldn’t happen anywhere else. Living at the top of a steep hill, my first drive is always about 1/3 of a mile to the bottom without ever touching the gas except very lightly to start moving. By the bottom of the hill the truck is in third gear and usually won’t downshift when I stop. If I then start there is a huge bang when it downshifts under load. I avoid the problem by manually shifting into 1st and 2nd gear only for the downhill. After that, the fluid has moved and warmed up and the truck is fine.
The truck has to go in for a brake job next week, so I’ll add that.
The transmission has always had a quirk that no one could duplicate or fix. It happens only when I leave home on a cold day, and wouldn’t happen anywhere else. Living at the top of a steep hill, my first drive is always about 1/3 of a mile to the bottom without ever touching the gas except very lightly to start moving. By the bottom of the hill the truck is in third gear and usually won’t downshift when I stop. If I then start there is a huge bang when it downshifts under load. I avoid the problem by manually shifting into 1st and 2nd gear only for the downhill. After that, the fluid has moved and warmed up and the truck is fine.