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VY Stalls under Deceleration only

Discussion in 'VY Holden Commodore (2002 - 2004)' started by JasG, Jul 8, 2018.

  1. fugly59

    fugly59 fugly59

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    This was exactly the post that I needed answered. Until the slanging match started:(
    I have a VY V6 with pretty much exactly the same problem.
    The main difference here is that it only appeared after I replaced the inlet manifold gasket.
    I have temporarily 'cured' the problem by disconnecting the MAF sensor. It runs absolutely perfectly except for 'maybe' that it idles a fraction higher. It also has the obligatory 'Check Engine' sign on the dash.
    I actually purchased a brand new MAF sensor thinking that this would fix the problem. Unfortunately, it runs exactly the same with the new unit connected. I am only running the vehicle to & from work at the moment (20 minutes each way) as I don't want to drive it too far without it running properly.
    I have also removed the throttle body assembly again. Cleaned it again. Took out the idle control unit. It was a bit dirty so I thought I'd found the culprit. Both hoses were connected onto the bottom. Still no difference. Looking at the tacho, it seems to stall when the transmission changes but only while coasting down a hill or into a corner.
    I am thinking that maybe 1 of the 3 hoses connected to the end of the 'plenum' (is that correct?) may be the culprit. I am confident with the brake booster hose but not the other 2. I don't even know what they do.
    If anyone has any answers or suggestions, I'd like to hear them.
    Thank You
     
  2. Trevor loves holden.

    Trevor loves holden. Well-Known Member

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    Maybe scan the fault codes and go from there, if it only started after you removed the intake one must ask what didn't you do correct.

    [​IMG]

    Could be anything, most probably your IAC valve not allowing air in on low revs to pick up your idle. Try shifting into rev then back to park you should see your tacho go up then down if its not then buy a new IAC.
     
  3. Utel67

    Utel67 Active Member

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    You do have the MAF on the right way, arrow facing the throttle body.
     
  4. fugly59

    fugly59 fugly59

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    Thanks for the reply.
    Trust me, my ONLY question is what didn't I do correctly?

    The picture you have is brilliant. The fuel pressure regulator hose is what I am going to approach first. It was pretty hard & I probably should have replaced it when I did the job but I didn't have that size.
    I did read the codes before I replaced the MAF sensor but it was all clear, but seeing as it runs fine without it connected, I thought that it had to be the problem. I am at least hoping that, because it runs fine without the MAF sensor, whatever I have done wrong is minor.
    Will let you know how I go.
    Thanks again.
     
  5. fugly59

    fugly59 fugly59

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    Thanks for the reply.
    I just double checked. I'm questioning everything.
    I actually left the original MAF sensor in position. I just removed the hose.
    The new unit is in the correct orientation.
    Thanks anyway
     
  6. Trevor loves holden.

    Trevor loves holden. Well-Known Member

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    Sounds like fuel pressure is the problem, didn't put the valve in the wrong direction only flows one way.
     
  7. fugly59

    fugly59 fugly59

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    Thank You.
    Excuse my ignorance but are you talking about the regulator valve on the fuel rail?
    I never removed that. The only thing that affected it was the hose to the back of the Plenum that I will be looking at tomorrow.
    If not, which valve do you mean?
    Thanks again.
     
  8. Trevor loves holden.

    Trevor loves holden. Well-Known Member

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    Discard sorry I was thinking of something else.
     
  9. fugly59

    fugly59 fugly59

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    I purchased a new IAC & installed it. No difference.
    Hoses have been replaced at the back of the plenum. No difference.
    Disconnect the MAF sensor again. Runs perfectly!!!!! I mean absolutely no sign of any problem. I took it on the expressway for a 30km run and it runs like a dream. Does anyone have any idea why it works fine without it connected?
    Does anybody know if I can short the MAF sensor so it doesn't come up with any 'Check Engine' on the dash. Or should I be searching the whole throttle body arrangement for a problem?
    I've had this car for 5 years, up until now, I've really enjoyed it. Maybe it's time for me to spend some money and take it to a mechanic who knows more about it than I do. Shouldn't be difficult.
    Thanks anyway guys.
    If I ever find out what I have done wrong, I will let you know.
    Cheers

     
  10. Utel67

    Utel67 Active Member

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    Try adjusting your throttle stop screw a little bit at a time, if you have a scan tool to check IAC steps it should be set around 30 steps when the engine is at running temp.
     
    Slowvxss likes this.
  11. fugly59

    fugly59 fugly59

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    Thanks.
    I will try anything at the moment. I'll have to wait till the weekend again to borrow the scan tool.
    I am sure I have done something wrong. Could be an injector seal or anything. But why does it work ok with MAF sensor disconnected?
    I will get to the bottom of it one way or another. Maybe next year.
    Thanks again.
     
  12. Trevor loves holden.

    Trevor loves holden. Well-Known Member

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    Someone else has idle problems after replacing the inlet Manifold, don't know why I've done mine and its fine, probably better to get it looked at. Removing the MAF plug probably puts the ECU into override and just sets the fuel and air as it sees fit. Spray all your contacts with contact cleaner and make sure they are a tight fit. MAF, TPS, IAC and O2 sensors work together.
     
  13. Slowvxss

    Slowvxss Member

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    I had the same problem on my old vt it kept stalling coming to stops, I adjusted the above and all was good.
     
  14. Trevor loves holden.

    Trevor loves holden. Well-Known Member

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    I would say as you removed the wire plugs to replace the gaskets you will have a bad connector on your TPS, remove and clean and close the female connectors a little so they are nice and tight. You can do it on the other 2 as well.
     
  15. fugly59

    fugly59 fugly59

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    Sorry, when you say adjust the throttle screw 'a little bit at a time', do you mean 1/16th of a turn or more like 1/2 a turn?
    I can't get hold of a scan tool this weekend so I will try without it for now.
     
  16. Trevor loves holden.

    Trevor loves holden. Well-Known Member

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    Wouldn't be touching any idle screw that's what's the IAC built for moving this screw misses with the ECU, When you cleaned the throttle body did you remove the IAC to clean out the carbon in the IAC housing to make sure its not blocked, like I said All those wire harnesses may not have good contact any loose fit or dirty connecters will send wrong messages to your computer, check your injectors for leakages too.
     
  17. Utel67

    Utel67 Active Member

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    Just leave it until you can get a scan tool to check what the IAC steps are reading.
     
  18. fugly59

    fugly59 fugly59

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    OK.
    I can't decide whether I'm extremely happy or just a complete idiot.
    I'll go with the happy, this has just been messing with my head for too long.
    I have found the problem.
    I did everything that was suggested including touching up the electrical connections, although I didn't end up touching the idle stop. I then took it for another drive. It was actually getting worse. It was stalling cruising all the time now, not just down hill. The only way that it wouldn't stop was if I put it in second gear. Just coincidence probably but it worked till I got back home. I thought that it had to be a split in a hose that was getting bigger.
    I finally found it, a split in the main concertina hose between the MAF sensor & the throttle body. It was on a seam on the underside, not visible from the top. When I took it off & turned it around, it wasn't really visible then either. Had to pull it apart to make it show up. I temporarily have taped it up with some gaffer tape. Runs like a dream, looks awful.
    So, just a word to say thank you to everyone for their suggestions & ideas. I also hope that this helps somebody else one day.
    Cheers Everyone
     
  19. Utel67

    Utel67 Active Member

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    Well done mate glad you got it sorted.
     
  20. henstepper

    henstepper New Member

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    Man I have had rough idle issues and splutter under acceleration and braking for a while. I have done pretty much everything To try and see the issue. Spark plugs, air filter, fuel filter etc etc. Might be worth looking into this myself to see if I have the same issue.
     

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