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Q: Its backfiring mostly while driving, loss of power, fuel consumption, motor doesnt idle smooth, P0300 code, no timing codes

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All of a sudden my motor runs like crap. I bought this motor used with around 80,000 miles on it. Just started backfiring out of the driver side exhaust (dual exhaust). Does it at idle and a lot when put in Drive gear. I did an oil change, spark plugs, spark plug wires, tried to set timing but its off 20-30 degrees after setting it right. No matter how I set the distributer its always +20 or more degrees. Like first setting in the distributer its at +20 and plug in the cam position sensor on the back of the distributer it goes to +30 degrees. I'm in Colorado so it should be at least 7 degrees. If its running this way and timing is way off no matter what, what are all the cases it could be? Was told timing chain and/or injectors.

My car has 160920 miles.
My car has an automatic transmission.

A: Hello. The symptoms you are experiencing c...

Hello. The symptoms you are experiencing can be caused by a wide variety of issues. If the ignition timing is significantly advanced, this is likely part of the reason for your misfires and performance issues. A few things I would check are the ignition module, crank position sensor, and cam position sensor. These all play a role in ignition timing and can cause issues if they are having any problems. It may also be possible that the issues are mechanical, perhaps due to a problem with the timing chain or distributor. If either of these components jump a tooth somehow, perhaps due to wear, they can cause the timing to advance or retard a significant amount. It may be possible that there is a need to look at the fuel injectors, however in most cases the fuel injectors do not affect ignition timing. If you are unsure, I would recommend having a professional technician, such as one from YourMechanic, come to your location to diagnose the cause of your misfires and performance issues.

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A: Hi there. The timing chain being at fault i...

Hi there. The timing chain being at fault is remote, had a similar experience with timing fixed (out of specification) regardless of distributor position. No timing codes. The upper distributor shaft bushing was excessively worn and replacing the distributor assembly took care of the timing issue. Once the timing issue is resolved. The backfiring, loss of power, and excessive fuel consumption could be the result of a leaking fuel injector(s) on bank (1). I recommend having your vehicle’s Check Engine Light On be diagnosed and repaired by a certified technician, such as one from YourMechanic.

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