How to Determine Why a Car Stalls at Intersections

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There may be lots of reasons a car stalls at intersections, but one that most people wouldn't think of is low automatic transmission fluid levels. Be sure to check the fluid when parked on a level surface. Do your best to not allow any lint or dirt to contaminate the dip stick before reinserting.

While not directly related, maintenance cycles for replacing transmission fluid and filter vary, but should be performed as suggested by the vehicle maker. Paying for a power flush may be worth it if you can afford it, but it's not essential. The most important part is changing it on schedule. The 5% of residue left behind will mean your 95% new fluid is being put to work.

Your gas may contain too much moisture. A clear plastic approved gas container filled and let sit for a few minutes, or upto 24 hours will collect moisture at the bottom (water is more dense then fuel). Name brand Heat and similar additives can evaporate water from the fuel. In some infrequent circumstances, a distributor coil may be cracked. A clogged, dirty or old fuel filter or fuel pump can be another cause. Another cause is your car's vacuum hose may be damaged and leaking, which may cause the engine to lose power.

The car may be just idling too low which can be adjusted very easily with a screwdriver. There is a small screw on the throttle body where the throttle cable connects to it you can adjust the screw to make the car idle smoother.

Steps

Low Transmission Fluid Level

1. 1
   Check the dipstick on the automatic transmission. Check the owner's manual for the correct procedure for your vehicle -- generally, manufacturers prefer testing with a warm engine.

   
   

Clogged Catalytic Converter

1. 1
   Look for stalling, no power when accelerating.
2. 2
   Look under the car at night after the vehicle has been running for a while; if the catalytic converter is glowing, it's probably clogged. You will have to replace the converter if you find this to be the problem.

Broken O2 Sensors

1. 1
   Look for initial idle OK after a cold engine start-up, but a warm engine idle will surge and stall.
2. 2
   After a few thousand miles of this, most cars will turn on the "check engine" light. You can take it to any AutoZone store(but they only check cars made after 1996 so if you have a old car you are out of luck) and they will read the codes for free. There can be any number of reasons for the "check engine" light to come on, so it is good to check. Codes complaining of unexpected lean mixture is a good indication of O2 sensor failure.

   
   

O2 sensors will typically last 60-75K miles. The good news is that you can buy an O2 sensor on-line for around $50 and they are generally pretty easy to replace. Another possible reason is that the engine is idling too low (the idle is adjustable) or the control module is going out, which is relatively inexpensive and easy to access and fix.

Tips

• If you have to check the fluid with the car running, make sure to set the parking brake. Most cars will ask you to put the car in Park or Neutral. Make sure you do not have the car in gear.

Warnings

• Often, you will have to reach into cramped, hot spaces to check your fluid. Check your manual for the proper location. Take care not to be burned by engine parts. Wear long sleeve shirts or gloves as appropriate. Also, when adding fluid, it is a good idea to use a funnel with an appropriate length of neck.
• Do NOT overfill.
• There are two types of transmission oil. Use the proper type for your vehicle.
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