Engine rumbling at slow down to stop.

Discussion in 'Gen 3 Prius Main Forum' started by thomassurdi, Nov 8, 2020.

  1. thomassurdi

    thomassurdi Member

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    My car is rumbling when I slow to a stop, and then for a few seconds after until the ICE shuts off, so it is the engine, not suspension or anything like that. There are no trouble codes yet. I think this happens only the first few times I coast to a stop after the engine has been cold. After it warms up it stops doing this. Then if I shut it off for a while and come back it starts doing it again. I have also noticed that the first time I accelerate every day there is a hesitation before a hard acceleration. I have recently cleaned the EGR pipe and cooler, and changed the spark plugs, ignition coils, and fuel injectors. The rumbling thing is new. Just noticed it last night, and again today. There is no coolant In the oil, or loss of coolant in the reservoir, so I doubt it’s the head gasket. Not really sure what else to check. Vacuum leak? Bad fuel, or filter?
     
  2. bisco

    bisco cookie crumbler

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    how many miles on her?

    did you clean the entire egr circuit?
     
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  3. thomassurdi

    thomassurdi Member

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    220,000 miles. Yeah I took the EGR off, pressure washed it and hit it with a few cans of brake Kleen.
     
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  4. Mendel Leisk

    Mendel Leisk Senior Member

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    How about the intake manifold; did you clean out its EGR passages?
     
  5. thomassurdi

    thomassurdi Member

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    yes, throughly cleaned the manifold including the little holes.
     
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  6. thomassurdi

    thomassurdi Member

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    This could be normal, but It almost seems like the ICE is kicking on at weird times, like if the battery is already showing a charge and I’m coasting to a stop after accelerating at fairly high RPM then when I come to stop the engine takes a few extra seconds to shut off, and sort of rumbles for a minute and then shuts down. If I let the car coast a bit and don’t step on the gas I can almost keep the rumble going. It’s strange. No idea why it’s doing that all of a sudden but it definitely wasn’t doing it a few days ago. Sometimes if I’m idle the ICE will kick on for like 5 seconds and then shut back off. Could it possibly be an issue with the inverter, or maybe something to do with the battery terminals? I did install new cells in the battery last year, but it’s been working fine for probably 25,000 miles.
     
  7. thomassurdi

    thomassurdi Member

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    Ok, here’s a better clue. I was sitting at a drive thru just now and the battery needed a charge so the ICE kicks on. After the battery was charged the engine started to shut off, but instead of shutting down it started doing the rumbling thing at low RPM, and then sort of started back up. Then after a few more seconds it shit down. So, there’s something going on with the way the engine shuts off. For some reason it doesn’t know when to or something. I thought for a while that it seemed like there was no rhyme or reason as to when the ICE would kick on, but now I know there something going on.
     
  8. bisco

    bisco cookie crumbler

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    throttle body?
     
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  9. Mendel Leisk

    Mendel Leisk Senior Member

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    Just to eliminate a variable, turn the heat/vent system completely off before coming to a stop; see if that reduces the engine run-on.
     
  10. thomassurdi

    thomassurdi Member

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    it would be surprising if it was the throttlebody since I have had it off and cleaned it when I did all the other work, but I guess it wouldn’t hurt to check it again and maybe inspect for vacuum leaks. Sometimes when my battery already shows a pretty good charge, the ICE still keeps running. It’s almost like at times the engine can’t decide whether to shut off or not.
     
  11. thomassurdi

    thomassurdi Member

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    Kind of sucks that I’m not getting any trouble codes to give me an idea here. I feel like all I can really do is keep driving until a light comes on.
     
  12. bisco

    bisco cookie crumbler

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    how are the mpg's?
     
  13. thomassurdi

    thomassurdi Member

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    44 or so.
     
  14. bisco

    bisco cookie crumbler

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    that's pretty good
     
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  15. AzWxGuy

    AzWxGuy Weather Guy

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    Hunting for crankshaft position maybe? Is the crankshaft position sensor a Hall-effect type? Don't know if there would be a code for that.
     
  16. cnc97

    cnc97 Senior Member

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    How’s the 12v health? If the 12v is low, the inverter output will stay high trying to charge it, and can keep the ICE running.
     
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  17. thomassurdi

    thomassurdi Member

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    It should be good since it was replaced maybe two years ago at the most, but I guess it couldn’t hurt to have it tested.
     
  18. thomassurdi

    thomassurdi Member

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    No idea about that. Not familiar with thise parts.
     
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