After engine has warmed up it loses power and there is a knocking noise

1998 FORD RANGER
211,000 MILES • 3.0L • 6 CYL • 2WD • AUTOMATIC
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DANGERRANGER01
  • MEMBER
  • 2 POSTS
I've already replaced the cam synchronizer and cam sensor, and it runs like a sewing machine until the thermostat opens and that's it. it loses power, and starts knocking somewhere in the top end. Help me!
Oct 18, 2020 at 3:20 AM
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KASEKENNY
  • Experienced Mechanic
  • 18,907 POSTS
Can I ask why you replaced the cam sensor and synchronizer? Was there a code or something else pointing to this?

Also, when you say it runs poorly when the thermostat opens, how do you know the thermostat is opening when it starts to run poorly? Or is it just that it runs poorly when it is hot and makes a noise?

Can you get a recording of the noise when it is running poorly?

I suspect that we have a poor running condition when it gets hot because we have a faulty sensor that is causing the engine to run poorly because it is giving the ECM faulty information.

This means we need to use a scan tool and monitor the o2 sensor information so that we can see if it is running rich or lean. Also, we can not eliminate the o2 sensors yet as when it is warm the engine is in closed loop where it uses the data from the various sensors to adjust the fuel to improve the performance of the engine.

So we need to scan for codes to find out if there is anything pointing us in the correct direction.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing
Oct 18, 2020 at 3:55 AM
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DANGERRANGER01
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  • 2 POSTS
the cam position sensor went bad and has been replaced. the truck purred like a kitten until the thermostat opened up and then it lost 50% of its power and started knocking up top somewhere.. i let it cool all the way back down and start it again. same thing, smooth as glass until it warms up and it's back to half speed and knocking. somebody help a brother out.
Oct 18, 2020 at 8:01 AM (Merged)
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