my truck's rpm hits the red line when cranked. What could cause this?
1 Answer
Hornet_2497 answered 5 years ago
The tachometer gets it's input from the engine computer based on the signal from the crankshaft position sensor. As long as it runs okay I would not be concerned. But if it's showing a check engine light or a code like P0320, you should check the crankshaft sensor first. You might be losing spark accompanied by the tachometer dropping quickly to zero and back up.