Am I the only one in the world with such a problem:(:(:( - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• Am I the only one in the world with such a problem:(:(:( by wasteland_TD on 24 Apr, 2006 05:39
• Hi everybody...
  
  The motor is 1.9TD AAZ and the pump is with LDA device from 1.6TD.I bought the car with this configuration mod.
  The sypmtoms:
  When the car is cold or worm the idling RPM are perfect, but if I drive the car on highway with 140-150km/h for about 30 minutes the idling RPM drops down - around 600-650rpm(i have tachometer) and becouse of that there is unpleasant vibrations.
  After 2-3 days, the idle RPMs gradually increases by itselfs.
  I brought the pump to the service-station.The people said - the pump is perfekt.
  And the car really runs GREAT.
  I changed the piston-rings and the hydro-lifters, the nozzles too.Also an intercooler.The pump-perfect.......and at last
  the there is still this FUC.... problem
  that`s make me CRAZY
  
  NOBODY can help here, no one has this problem ((((((((((
  pleease for your help   :oops:  :oops:  :roll:
  
  BTW- I saw that my balancer is wobbling -not much, but soon i will fix that.Is there any connection between this and my terrified problem
• #1 by shwartzbewithyou on 24 Apr, 2006 06:33
• Are you sure that from driving at 150km/h for 30 minutes straight it isn't just overheating?  I'd be tired to if I was that diesel 1.6.
  hmmm....Does it run like this when it's just hot, or only after that 30 minute scream down the road?
  Does the timing advance make a difference when it's cold?
• #2 by wasteland_TD on 24 Apr, 2006 07:52
• I`m sure that there is no overheating - the temp is always at 87-92 C
  
  hmm, i have not checked the timing advance when the motor is hot...
  can the timing advance alters when the motor goes hot?
  currently my advance is 0.92
  
  any ideas??
• #3 by QuickTD on 24 Apr, 2006 08:21
• Fuel density changes with temperature. If you run the engine hard for many miles the fuel in the pump and tank heats up and loses density. If the governor isn't adjusted correctly, the idle speed will drop due to the lower density fuel.
  
  Sounds to me like you have too much pressure on the main governor springs and too little on the idle spring.
  
   Warm up the engine, then back out the adjustment screw that the throttle lever rests on until the idle speed stops decreasing or reaches 750rpm, then adjust the idle speed back up at the small idle lever on the back of the pump. This should give you a more stable idle.
• #4 by wasteland_TD on 24 Apr, 2006 08:33
• ok QuickTD..
  so I must turn the screw(residual fuel pressure, right?) until the idle RPMs reaches 750-800 and then to adjust the idle with the small lever
  but what can I do if the idle RPMs increases after 2-3 days  :roll:  :roll:
• #5 by QuickTD on 24 Apr, 2006 08:41
• If you get the adjustment correct the idle speed should not increase or decrease more than 100-150rpm from cold to hot. If you find that the idle still changes when the engine is hot, then you still have too much residual pressure and you need to back the residual adjustment out even more.
• #6 by janb on 07 May, 2006 01:10
• one of my AAZ (NA) idles very low and vibrates when cold, then better when warm, so will this residual pressure be the issue?
• #7 by QuickTD on 07 May, 2006 05:23
• Quote

  one of my AAZ (NA) idles very low and vibrates when cold, then better when warm, so will this residual pressure be the issue?

  
  
  Could be. The residual adjustment affects the sensitivity of the idle governor. Excessive residual pressure on the main governor springs will pretty much disable the idle governor spring and make the idle speed very sensitive to changes in fuel density, temperature and load at idle.
• #8 by wasteland_TD on 07 May, 2006 06:10
• QuickTD
  I saw the pump of my brother`s VW Passat(AAZ).The position of the screw for residual fuel quantity on his pump was just like my screw.
  But my idles drops when the engine goes hot...
  Before a couple of weeks you said that may be I have too much residual fuel pressure and I must back the residual adjsutment.
  
  what have I done...?!  
  When the engine goes HOT and the idles drops at 600-650,
  I turn the screw for residual fuel quantity !!clockwise!! may be 3-4 turns
  the idles raises at 850     .
  Next morning when the car goes warm the idles stays at 1050, i turn out the the small idle lever on the back of the pump and leave the rpms at 950-980.When the engine goes hot the idels drops at 800 and I was very Happy  
  Now there is another side effect.The throttle becomes nice HARD.Before, when the engine was hot, the performance in low idles was terrible.
  Now is FINE    
  When change the gears form second to third or third to fourth(no sense) at 1600 RPMS, there is no a such terrible "hole" when I step on the gas.
      The throttle now is hard all the time....hot, cold..
  QuickTD...
  I don`t know what have I done actually, whether I observe your advice but now that is quite different car.
  May be the fuel consumption will raise up after this "set up"and the question is how much.....?    
  Or.. will that harm my pump  :roll:
• #9 by steve on 07 May, 2006 15:17
• By "balancer" do you mean the pulleys connected to the forward end of the crankshaft?  If so, then you better fix that very soon.  Mine did that and I was going to get around to it... and in the meantime the bolt broke and everything had a comeapart...  Trashed a 1 year old cyl head.  If yours is loose enough to wobble then it may have affected the timing belt timing.
• #10 by dennis m king on 07 May, 2006 17:33
• waste land i think you turned the fuel screw the way you are talking.
  if you turned the screw with the jamb nut not touching the throttle lever that has the throttle cable connected to it you did something else like turning up the power(max delivery) of the pump.
• #11 by wasteland_TD on 08 May, 2006 00:25
• no dennis, that`s not the fuel screw, i have never touched that screw, and I don`t want becouse I will increase the fuel consumption.
  The screw is exactly - residual fuel quantity or pressure i don`t know the right name.
  I don`t know too how this screw is working