EGR, PCV, intake manifold Cleaning doesn't fix shudder/rough idle

Discussion in 'Prius c Main Forum' started by RogersPruisC2014, Mar 24, 2022.

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  1. RogersPruisC2014

    RogersPruisC2014 New Member

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    I've been having the rough idle and shuddering with my engine and even some at speeds 20-30 mph. I unplugged the EGR which resulted in better performance though there is still the rough engine condition.

    I cleaned the EGR, PCV valve, and intake manifold extensively and reinstalled/plugged back in which results in the same poor performance. To a degree it is better, but still no solution to the overall problem.

    So I get the code P0403 which is "the engine control module (ECM) has detected the engine exhaust gas recirculation (EGR) circuit has malfunctioned"

    Is there any prior experience with a complete cleaning, but no real improved result? Do I dare replace the EGR and see if that fixes the issue? Especially if it still produces a less degree of rough idling even when the EGR is unplugged.

    Any insight will be appreciated!!
     
    #1 RogersPruisC2014, Mar 24, 2022
  2. ChapmanF

    ChapmanF Senior Member

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    Where did you look that "translation" up? I don't think it's quite right.

    In a Gen 3 liftback repair manual (and I'll bet lunch it's the same for the c), the detection condition for P0403 is "open or short in EGR valve circuit". That is, it is strictly an electrical issue between the valve motor and ECM and the wiring and connectors in between.

    The value of going to the right place to look up what the code means is that you then have a very good idea what sort of issue you need to be looking for and how to find it.
     
    #2 ChapmanF, Mar 24, 2022
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  3. douglasjre

    douglasjre Senior Member

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    But an EGR valve
     
    #3 douglasjre, Mar 27, 2022
  4. ChapmanF

    ChapmanF Senior Member

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    ?

    Knowing whether the computer is telling you about a valve problem or about an electrical circuit problem ranks right up there with the most important information the car's self-diagnosis systems can give you.
     
    #4 ChapmanF, Mar 27, 2022
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