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Q: Strange noise while idle and worst when decelerating

asked by on March 20, 2017

I bought my '94 Mercury Topaz V4 Automatic about a month ago. I pulled the codes and it had a P158 for the MAF sensor. I replaced the MAF sensor, air filter, PCV , and fuel filter. I was on the freeway today and I noticed it was making this exaggerated revving sound after 60 mph. Then it slowly and consistently lost speed. I immediately got off the freeway in time to coast into the gas station as it cut off. Then when I tried to restart it, it won't turn over. It was the darn distributor. But after getting her started again I have a new sound. Yay! Let me know what you think. https://youtu.be/p2Ooeccexss My car has 466339 miles. My car has an automatic transmission.

My car has 446000 miles.
My car has an automatic transmission.

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Hello, thank you for writing in. The knocking noise from the video may be related to the new distributor that was installed. The distributor and timing can cause pre-ignition of the air-fuel mixture. This causes the rough idle and the engine knock. With that being said, you should set your timing and check the distributor. From there, also clean and inspect the throttle body, position sensor, and the idle air control valve. Make sure your spark plugs are brand new as well. For more help with further diagnostics or issues, contact our service department.

Mercury
Noises
L4-2.3L
1994
Topaz
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