RPM needle jumping and car jerking while stopped
The tachometer gauge goes crazy during startup and while idling at traffic lights, causing the car to worryingly jerk back and forth. Despite the needle jumping, the actual engine RPMs do not drop, and the issue generally stops after revving the engine. Drivers experiencing this are often told it is an alternator problem.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Revving the engine to temporarily stabilize the gauges.Did this help you?
- 2Taking the vehicle to an auto parts store to have the battery and alternator tested.Did this help you?
- 3Checking and replacing ground wires.Did this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“The rpms do not actually go down (in case you can't hear it in video) just the gauges go crazy.”source ↗
“I keep being told this is an alternator thing, I'm not sure though. It generally stops after I rev.”source ↗
“for a couple of months the RPM or tachometer’s needle has been jumping a lot when I start my car. It’s not only happening while I start it and it’s idling, but it also jumps while I’m stopped at traffic lights.”source ↗
“When the needle jumps, my car also jerks back and forth and it can be slow or fast. Honestly, it’s very worrisome”source ↗
Where this came up
People with this problem also raised
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