What can cause a pull on the engine?

Discussion in 'Chevy Truck Forum' started by Stob, Jul 1, 2017.

  1. Stob

    Stob Full Member

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    02 Silverado 4.3 V6. When I have the A/C on, I can feel when the compressor kicks in, a slight addd pull on the engine. But what about when the A/C isn't on? When approaching a hill, I ease down on the gas, the converter unlocks, the rpms increase as they should. But 2 seconds after the unlock, I can feel a distinct pull on the engine, the rpms slow some, and it stays that way until I'm over the hill. The A/C isn't on, but it feels just like when the compressor kicks in. What could cause this?
     
  2. JTWard

    JTWard Full Member

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    Well in my truck, which is a lot older than yours, but if I have the interior air system on, even on very low vent and if you have the controls for the defrost the temperature of the air going up to the windshield includes the A/C compressor , will cut in and out. It's trying to keep the air your using to defrost the windshield of fog so it try's to keep the air the right temperature. Now My truck is a long way down the road from yours, but mine does the same thing as yours does. The compressor kicks in and out. If you had a V8 you most likely not feel it so much.
     
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  3. Stob

    Stob Full Member

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    I understand the compressor runs in defrost mode. This is not the case. I keep a temp probe in the vents just to watch the air temp, and it doesn't change. I'm thinking something is effecting the computer controls, oxygen sensor, mass air sensor, something.
     
  4. JTWard

    JTWard Full Member

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    OK so you mean with the A/C off, or do you turn off the whole system and your still having a engine snag pulling down the rpm's ?

    Does the transmission shift up and down OK ?
     
  5. Stob

    Stob Full Member

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    Just the fan on low with no heat. Moving air. Trans shifts fine.
     
  6. JTWard

    JTWard Full Member

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    OK, Has it always done this or is this something new ? And when you say you ease down or ease up on the gas pedal ?

    "When approaching a hill, I ease down on the gas, the converter unlocks, the rpm's increase as they should. But 2 seconds after the unlock, I can feel a distinct pull on the engine, the rpm's slow some,"

    If the truck is starting on an upgrade, it'll downshift, which will mean the RPM's will increase. But if your truck is slowing down and nothing mechanical is putting a strain on the drive-train, then I'm confused Is the transmission slowing down or is the engine slowing down pulling the transmission with it ? A 4.3 V6 is a pretty stout engine. If I'm not wrong it's a 60 degree just like a V8 and shears a lot of the same architecture. But your problem seems odd, under-powered or Normal operation ? Have you talked to a Chevy dealership about what the drag is all about ?
     
  7. gmctrucks

    gmctrucks Full Member

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    Any codes and maybe the Trans is slipping
     
  8. Stob

    Stob Full Member

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    When I approach a hill, the converter unlocks and the rpms go up, as they should. Then I can hear and feel something that either puts a physical drag on the engine/vehicle or something is effecting the engine performance. I don't have a code reader, but I'm seriously thinking about getting one.
     
  9. leolkfrm

    leolkfrm Full Member

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    its a 6 cyl, in a big truck, and pulling a hill.....sounds normal, clutch fan would be kicking in too
     
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  10. Stob

    Stob Full Member

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    No help here, moving on.
     

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