Car idle sputters and engine dies when AC clutch engages

ANSWER : Hi there. In most cases, when the AC compressor and clutch engage, it will draw extra ’power’ from the engine and cause the idle to slightly drop. However, this can cause existing issues to be amplified. For example, if you have dirty fuel injectors, mass air flow sensor or EGR valve on the vehicle, the activation of the compressor clutch will make the symptoms worse and more noticeable. However, if the compressor bearings or clutch is dragging, it can "bog" down the motor even more. It’s a good idea to have a professional mechanic come to your location to complete a car idle is rough inspection to determine if it’s a normal fuel system issue or if the AC system is the source of this problem.

ANSWER : Hello, thank you for writing in. Although the pulley is still spinning, the compressor has likely failed. If it is not properly regulating pressure in the system, one of the first signs is a warm air conditioner. Considering yours is not cooling off, the pressures are not correct. If you believe the compressor is working correctly, you may want to check for a clogged line before replacing it. Keep in mind, a blocked line has likely put extra strain on the compressor, and may cause premature failure. For more help with testing or replacing the compressor, contact our service department to schedule an appointment.

ANSWER : Hello there, many common faults will cause your 2008 Nissan Altima to shut off when put in drive or reverse. The first step in diagnosis is to check the transmission for leaks, and the fluid level and condition. Once the transmission fluid is checked most common faults are the torque converter, Idle air control valve, vacuum leaks, or a wiring harness fault. A qualified Technician such as one from YourMechanic will be able to diagnose your engine shuts off when put in drive and make any repairs required.

ANSWER : Hi there. In both cases, when an AC system is not working and a warning light is coming on the dashboard, typically a professional mechanic will complete the same initial inspection, which is to download the stored error codes that triggered the warning light initially. This tends to give them an idea as to what is causing the problems. This could be something as simple as an electrical relay that is faulty or loose or an indication of a computer related "glitch". Either way, the best way to move forward is to have a professional mobile mechanic complete a check engine light inspection.

ANSWER : It is very possible that the engine has been damaged beyond repair. Usually when the oil light goes on and the vehicle is low on oil, especially when a loud noise is heard right before the vehicle died, it is very likely that the engine is blown and would require replacement in order to continue driving the vehicle. I would recommend having the vehicle checked with a no start inspection. Consider YourMechanic as this service can be completed at your home or office.

ANSWER : This sounds like there is a problem with the MAF (mass airflow) sensor. When your vehicle is cold, the PCM (Powertrain Control Module) is in what is known as open loop. Open loop is a preprogrammed program put in place for warm up. Closed loop is when the PCM begins using the sensors to adjust fuel ratio. The primary sensor the PCM uses to make decisions is the MAF. I’m leaning toward three possible problems here. The MAF may have been damaged during cleaning, the connector may have a bent pin from disconnecting and reconnecting its connector or the boot that connects the MAF to the throttle body has developed an air leak.

Before condemning the MAF, make sure there isn’t any unmetered air entering the motor after the MAF. This will confuse the PCM and things just won’t work correctly. Unmetered air is what we call it when there is a leak between the MAF and the throttle body.

Of course, make sure the MAF has been plugged in. If it is, disconnect the connector and inspect the pins. It is fairly common for the small electrical pins in all sensors to get bent over when reconnecting their connector.

It is very easy to damage sensors in the area of the throttle body when cleaning it. Carburetor cleaner can damage sensors. The one I am particularly worried about is the IAC valve. These can stick and cause many different idle control issues.

If this isn’t of any help to you, I recommend having a certified technician, such as one from YourMechanic, diagnose your stalling condition for an accurate repair.

Good luck!

ANSWER : If the clutch pedal is not moving and the clutch is partially applied, then the clutch release bearing may be damaged and the fork is jammed into the clutch forcing it to slip.

For the no start condition on the starter, try tapping on the starter solenoid and see if the starter engages. If the starter does not engage, then remove the starter and see if it engages without the engine. If the starter does engage, then try to crank the engine over by hand and see if it turns. If the engine does not turn, then the bearings may be locked up or there could be an issue inside the engine. If the engine does move, then the starter needs to be replaced. For the brake lights not shutting off, the brake light switch could be applied as it may be not connected properly on the brake pedal. Check to see the location of the brake pedal light switch and adjust the location to relax the switch. If the switch is relaxed, then the brake light switch would need replaced.

I recommend seeking out a professional, such as one from Your Mechanic, to help you with the no start and clutch issue.

ANSWER : Hi there.The catalytic converter has two oxygen sensors. One oxygen sensor is positioned in front (upstream) of the catalytic converter and the other oxygen sensor is positioned at the rear (downstream). If the upstream oxygen sensor is working properly, its readings should fluctuate from when the car is at operating temperature and when running in a closed loop. When the oxygen sensors have readings that are similar to each other, it is an indication that the catalytic converter is not working as intended. If the voltage of the downstream oxygen sensor decreases, and begins to fluctuate like the upstream oxygen sensor, it means that the oxygen levels are too high and the Powertrain Control Module (PCM) will store the P0420 trouble code. This could be caused by a cracked exhaust manifold, damaged sensors or catalytic converter or electrical harness that controls the the sensors. It would be a good idea to have a professional mechanic complete an engine is misfiring inspection.