79 Seville - weird problem?? PCV Line.
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5.0 and 5.7 Discussion, 79 Seville - weird problem?? PCV Line. in Cadillac Engine Technical Discussion; I have a T connection on the vacuum line from the throttle body to the PCV valve. Sorry engine 5.7 ...
  1. #1
    geruk is offline Cadillac Owners Member
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    79 Seville - weird problem?? PCV Line.

    I have a T connection on the vacuum line from the throttle body to the PCV valve. Sorry engine 5.7 EFI gas. When I blank off this connection with a plug, and then run the car the engine races when ever I step on the accelerator. It's fine at idle but races very high once the accelerator is moved?? When I connect something to the T connection, cruise, EGR etc., all works okay. Anyone seen this, why is it happening?

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    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: 79 Seville - weird problem?? PCV Line.

    I'm going to more this to the 5.0/5.7 forum. You may get more help there.

  4. #3
    cadillac_al is offline Cadillac Owners Connoisseur
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    Re: 79 Seville - weird problem?? PCV Line.

    Where does the vacuum line go? It must go to something. The computer uses a vacuum signal but I can't remember where it's connects to the engine.

  5. #4
    carnut is offline Cadillac Owners Master
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    Re: 79 Seville - weird problem?? PCV Line.

    You need to be more clear. Any engine revves up or races when the pedal is depressed. Need to know where the other end of the hose ends up. A fuel injected engine will run faster with a vacuum leak, unlike a carb'd car which will idle rough with a vacuum leak. Most people on this forum were born after this car was made!! You need to purchase a factory service manual and read it like it was a porno novel!! If you know how, provide pictures. On the web, we have no eyes!

  6. #5
    geruk is offline Cadillac Owners Member
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    Re: 79 Seville - weird problem?? PCV Line.

    Thanks for the help guys, I finally sorted it out, the PCV vacuum line had another connection in a very unreachable place that was not obvious until were pulled everything off. This connection was connected to the gas tank vapour recovery system, the vacuum was sucking in fumes from the gas tank, causing engine to race. We had a manual, stripped all the vacuum lines, started from scratch and put everything back as per the manual, all ok now.

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