Q: Car will start and run smoothly but will die when you try to accelerate.

asked by on December 27, 2016

Car will start and run smoothly but will die when trying to accelerate. In neutral if you hit the gas abruptly, there is a bit of hesitation but it will often rev above idle and if you keep it well above idle it runs smoothly and accelerates like normal if you hit the gas but if you allow it to approach idle it will die again. After it warms up it will no longer idle but will start easily every time. If you hit the gas hard again after it fires you can get the engine past the idle and again rev the engine smoothly as long as you do not let it get below about 1500 RPM. I have replaced the IAC and checked the resistance from the throttle position sensor (DVM shows very smooth change in resistance when carefully opening the throttle, no dead spots detected) Thoughts? Rick

My car has 180000 miles.
My car has an automatic transmission.

Hi there. There may be a misfire on a cylinder that is causing the engine to hesitate on acceleration. Check all of the spark plugs and wires and see if they have burn marks. If there is burn marks on the spark plugs then I recommend replacing them. Also, check to see if the fuel injectors are working. While the engine is running, unplug one fuel injector at a time and see if the engine begins to hesitate even more. If so, then the fuel injector is working. If the engine does not hesitate any more, then the fuel injector may not be working or the cylinder could have a gross leak. If the spark plugs, wires, and injectors are working and are in good condition, then check the engine for compression and see if the cylinders are equal. For the cylinders that are low in compression, there could be a burned valve or the rings on the piston could be stuck shut and not expanding. If you need further assistance with your engine misfiring, then seek out a professional, such as one from Your Mechanic, to help you.

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