Car cutting off while driving

ANSWER : There are reports that the replacement alternators will not communicate with the engine computer and will not charge correctly. I recommend using only the manufacturer approved replacement part. It can be new or remanufactured but approved for use in the vehicle. Some lower cost alternators on the aftermarket will have charging problems since they will not communicate with the ECM on the vehicle and will stop charging.

ANSWER : Hi and thanks for contacting Your Mechanic. If your engine light came on for the secondary air pump sensor, then it is possible that the secondary air pump (smog pump) has failed. The pump has oil in it and if the pump seized up, the case may have broke and leaked out the oil or burned the oil causing the smoke. Also, there could be a coolant leak causing the smoke under the hood. If the pump is not working, then I suggest replacing the air pump. If you need further assistance with the engine having a lack of power, shaking, and crating smoke under the hood, then seek out a professional, such as one from Your Mechanic, to help you solve this issue.

ANSWER : Hello. I would need to know the model of your Toyota to be able to give you the best information. From what you are telling me though it sounds like the crank sensor harness may be damaged or that one of the main grounds may not have been properly installed when the transmission was put back in. Both of these will cause this to occur.

I usually install a scan tool and watch the crank signal to see if it changes when the stalling occurs. If it does then either the sensor or the harness has a problem. If the reading is fine then the grounds need to be checked for a loose connections.

If you need to have this repaired, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose your starting issue firsthand and repair this.

ANSWER : Hi There,
It sounds like you may have a dirty or faulty mass air flow sensor. The problem this can cause may also be compounded when the engine is cold due to the change in air density in cooler weather. The mass air flow sensor monitors air intake as it is mixed with fuel prior to being injected into the motor. This sensor relays information about fuel and air temperature, air speed entering the motor and many other things to the ECM which uses this to make adjustments to fuel supply to the motor. A dirty or faulty sensor can cause an imbalanced air/fuel load to be supplied to the motor which results in an over fueling or under fueling situation depending on the conditions. This type of inconsistent fuel supply to the motor may cause a hesitation, loss of power, a jerking reaction, potentially a bit of black exhaust smoke and typically a strong smell of fuel when this sensor is malfunctioning. I would suggest having a professional from Your Mechanic come to your home to diagnose and inspect your vehicle.

ANSWER : It sounds like your idle air control valve could be failing. The idle air control valve is responsible for maintaining the proper amount of air into the intake while the vehicle is slowing down to a stop and resuming idle speed. When this valve fails, it can cause the exact symptoms that you described. I would recommend having the idle air control valve inspected by a qualified professional to determine if it is performing properly. If the IAC valve has failed, I would recommend having it replaced at your earliest opportunity.

ANSWER : This may be a result of low transmission fluid or potentially a faulty transmission control module. A faulty transmission control module may cause a delay in acceleration or erratic shifting of gears. The transmission control module has various sensors such as vehicle speed sensors, wheel speed sensors, throttle position sensors, turbine speed sensor, and transmission fluid temperature sensors that all direct information to it in order for it to perform it’s function. Other functions controlled by the TCM are components such as a kick down switch, traction control system, and cruise control module. Any of these may also affect the way the transmission control module performs and controls the transmission and the shifting of your vehicle. I would suggest having a professional from Your Mechanic come to your location to properly diagnose your transmission problem.

ANSWER : Your vehicle sounds like it is starving for fuel. If the fuel pump is going bad it may make noise. The lack of power may be due to a loss of fuel pressure, mass air flow sensor problem, or one of the computer sensors like the camshaft or crankshaft sensor is malfunctioning.

I recommend having the fuel pressure checked and getting the computer scanned for codes to the sensors. These checks will help pinpoint the problem. If decide to get this fixed, consider YourMechanic, as a certified technician can help you diagnose your stalling issue and driving symptoms. An accurate repair can then be made once the problem has been pinpointed. Goo luck.

ANSWER : The initial failure was likely caused by a sudden fuel system (e.g., failed fuel pump) or electrical (including ignition) faiure. Prior to performing diagnostics be sure you have a fully charged battery that passes a load test. Then, confirm that the engine immobilizer system (security system) is not activated thus preventing the car from starting. If the starter motor is not functioning, check for power to the starter motor when the key is held in the "start" position. If there a large voltage drop at the starter motor or no power at all, you may have a faulty ignition switch but you do have to check out the entire starter circuit, which includes grounds, wiring (some of which is very heavy cabling), fuses, relays, the ignition switch and terminations. On the other hand, if the starter motor is getting power but the starter doesn’t work, then the starter is condemned and replaced. If you desire that a certified mechanic resolve this, please simply request a no start diagnostic and the responding certified mechanic will get the problem diagnosed and repaired for you. Please let us know if you have further concerns or questions as we are always here to help you.