Why would car shake when accelerating

ANSWER : It is very possible that you have a valve cover gasket or spark plug tube seal leak on your vehicle. These type of leaks will allow oil to leak onto the spark plugs causing misfires. When the engine misfires due to oil getting on the spark plug, the engine oil will burn. Since oil and tires are both petroleum products, they will both smell similar when they are burning. I would recommend having an oil leak inspection performed by a qualified professional to determine if there is an oil leak. Consider YourMechanic as an Oil/Fluid leak inspection can be peformed at your home or office.

ANSWER : Hello, thank you for writing in. The engine is likely sensing an issue and compensating for it. When you restart the vehicle, the component may be passing its start up tests, and the engine stops trying to outperform itself. Start by having the vehicle scanned for diagnostic codes. If there is another sensor to blame, it may show up there and make diagnostics a lot easier. If not codes come up, you will want to test the fuel pressure available at the engine, and make sure the fuel system is working properly. You can also clean the throttle and test the throttle position sensor. For more help with diagnosing and resolving the issue, contact our service department to schedule an appointment.

ANSWER : Hi there – there are 2 failures in particular that are likely candidates at your mileage level – a failed timing belt, and a fuel pump malfunction. If you don’t hear the fuel pump run for a few seconds when you turn the key to "Run", check fuses and the fuel pump relay. Otherwise, I recommend a no start inspection performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, and give you an accurate assessment of damage and cost estimate for repairs.

ANSWER : Shaking or vibrating may be caused by many different things such as faulty spark plugs, poor fuel pressure or misfires. Other things such as a faulty idle air control valve may cause the engine idle to drop below the normal idling RPM which may also cause the motor to shake or vibrate more than normal. This creates a loss of power that resonates throughout the motor additionally causing other problems with ignition and fuel timing. Anytime a misfire is caused, this causes an imbalance in the motor which will cause the motor to shake or vibrate. The other issue that may cause this type of shaking or vibration is a broken engine mount. Engine mounts are generally rubber mounted braces that hold the engine in place to the chassis of the car. When these break or become weak or faulty, this may cause the engine to vibrate heavily. Due to the many possible causes of this type of shaking or vibration, I would suggest having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

ANSWER : The odor of gas is due to misfiring. Check engine compression and check for any exhaust restriction preferably by measuring exhaust back pressure but you can also infer exhaust back pressure by testing engine vacuum. If compression is good and there is no back pressure, the other usual suspects are clogged fuel injectors (remove from fuel rail and send out for cleaning; cleaning injectors on a car is a waste of time because each injector has an internal replaceable filter basket that MUST be replaced), the throttle position sensor, the throttle body, EGR and vacuum leaks, and so forth. It would probably save you time and perhaps needless expense in parts replacement if you request a rough running diagnostic. if you were to request such a diagnostic from YourMechanic, the protocol is pretty standard: a certified mechanic will test for ignition, fuel system, air induction and/or engine sensor problems and these possibilities are tested, in a sequence, using a diagnostic "decision tree". Often, the problem is limited and straightforward, that is easily repairable. There is a good chance of that so I recommend that you request a rough running diagnostic and the responding certified mechanic will travel right to your location and get this diagnosed and resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic.

ANSWER : Shaking with the a/c on can be caused by a number of reasons. The a/c compressor puts a lot of strain on the engine because the compressor is similar to being a small engine itself. When the a/c is switched on, the engine control unit should trigger components such as the idle speed/air control motor, to increase the idle slightly to compensate for the extra drag of the compressor. If that does not happen, then the additional drag can cause a low,shaky idle and even cause the engine to stall. Stalling can happen more often with the a/c on and turning the steering wheel as the power steering pump also creates drag on the engine. Excessive shaking can also be attributed to weak/broken motor mounts as well.

Have a certified technician look into the engine shake to isolate the exact cause.

ANSWER : Hi there. Typically when you accelerate and the engine or steering wheel is vibrating, it’s due to motor or engine mounts being worn out. During acceleration, the motor mounts the engine vibrates naturally as RPM’s increase. Engine mounts are the component responsible for securing the engine of a vehicle to the chassis. They come in a variety of shapes and sizes to fit a wide variety of needs, but they all serve the same purpose of mounting the engine and dampening engine vibration. However, it’s also possible that a vacuum leak exists or something entirely different is causing this vibration. It’s probably best to have one of our professional mechanics come to your location to complete a steering wheel is vibrating inspection. This will allow them to isolate the source of the problem and recommend the correct repairs.

ANSWER : Hi there. The technician you went to could be on to something there with the shaking and possibly having moisture in the fuel tank. However, it sounds like you could be having an intermittent electrical component fault which can be difficult to trace when everything is working properly.

If the vehicle does not turn over, then the starter is not engaging. Check for a loose battery terminal first and have a battery test performed with a digital tester to determine the cold cranking amps and state of health.

The starter could be faulty with worn contacts internally. Sometimes they complete the circuit, sometimes they don’t. Worn contacts can create intermittent problems and require replacement of the starter assembly to repair. There could also be a relay, ignition switch, or wire harness fault.

Inspecting these items requires the use of a digital volt/ohm meter and the electrical wiring diagram. I strongly suggest acquiring a qualified technician to perform an inspection and avoid replacing unnecessary parts. If you would like to have this scoped out by an expert, a certified professional from YourMechanic can come to your car’s location to diagnose the hard start and follow through with repairs.