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Q: Car Hesitation Acceration

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When I'm driving my car, and it is driven for a while, and is in the normal operating temperature. It runs normal, but after I shut it off, and come back and when the engine is still warm it hesitates to get up to speed. But when I continue to drive it the hesitation goes away, and performs normally during everyday driving. Also what I discovered when I go up a hill when the engine is hesitating is that it wants to stall, and there's no power when I push the gas pedal down. Secondly I heard some backfiring from the exhaust when the car is trying to go up hill. Lastly when the car is cold it performs normal, there's no hesitation or problems as detailed above. Thanks

My car has 216745 miles.
My car has an automatic transmission.

A: First, there are many possibilities with su...

First, there are many possibilities with such a symptom, but I can make a few assumptions based on you detailed description. Primarily, it sounds as if your car has a rich running condition when it is acting up. Cold motors require more fuel to run, so with a rich running condition, it will run normally when cold. When you get into your car in the morning, it is cold and you drive as you normally would while the car goes through it's normal warm up cycle. When you turn the motor off, I suspect there is an internal fuel leak allowing fuel to flow into the intake manifold. When you restart your engine, it now has a rich running condition with a fully warmed motor. As you drive, the motor eventually uses the extra fuel and it eventually returns to normal operation. Backfiring out the exhaust is another reason I think this is occurring. That loud pop you hear is the extra fuel lighting in the hot exhaust system. That lack of power up hill is simply a result of too rich a fuel mixture. The motor is unable to efficiently combust the fuel resulting in a lower power output.

Some possible causes of a rich running condition that you are experiencing are as follows.

  1. Exhaust leak that goes away after driving. This will give the computer an inaccurate oxygen reading.

  2. Problem with the MAP (Manifold Absolute Pressure) sensor. This has a rubber hose connected to it that supplies vacuum from the intake manifold. If this hose is damaged, numerous symptoms will occur.

  3. Oxygen sensor is slow to warm up. Bad oxygen sensor heater circuit.

  4. Leaking injector or injectors.

  5. Leaking fuel pressure regulator.

These are the most likely, but there are a number of other possibilities. It will take some diagnosis time by a qualified technician. Your older OBD I Accord will be a challenge for many newer technicians that haven't had the privilege of working on one before. I recommend booking an appointment with one of your technicians. Our system will set you up with a qualified technician to diagnose your acceleration issue.

Good luck!

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