What Causes Manual Transmission Car to Shake When Starting Cold but Not When Warm?

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Possible issues include engine mechanical faults. Below is a detailed explanation: Reasons for cold start idle shaking include: Engine mechanical faults. For example, uneven cylinder pressure; intake system faults, such as intake pipe leaks. Excessive carbon buildup on intake valves and intake pipes, too much dirt on throttle body and intake pipe walls; engine management system faults. For example, incorrect coolant or intake temperature signals, wiring faults, etc.; ignition system faults. For example, excessive carbon buildup on spark plugs or incorrect gap, leaking high-voltage wires or distributor cap, damaged ignition coil, etc.; The correct approach is: If the car doesn't start on the first attempt, wait 20 seconds before trying again. After starting, don't rush to drive—allow some warm-up time. Generally, it's most fuel-efficient to start driving when the coolant temperature reaches 40 degrees.