JX 1.6TD Smoke on full throttle at Low RPM - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• JX 1.6TD Smoke on full throttle at Low RPM by BajaVWCamper on 31 Jan, 2020 10:01
• Hi Guys,
  
  After putting 5k Km on my rebuilt JX I am now to the point where i want to fine tune and iron out the smaller issues on the thing.
  She runs great, has good power and decent mileage (for a Hitop-Vanagon anyways).
  
  The Issue now is i feel i get more that what i consider "reasonable" black smoke when acceleration away from a standing start, for example at a stoplight.
  WOT at higher RPMs such as highway or freeway cruising then its just fine; I can hold her wide open and see no smoke at all.
  
  Seems to me like if the Injection pump is injecting more fuel than it should at lower RPMs but them evens out to where it should be at higher RPMs.
  Could the Turbo Boost Can be adjusted to far? (Giving extra diesel before turbo boost)
  
  When i first got The car the injection pump settings were totally off and nowhere near where they should be (had too screw the max fuel screw down 6 full turns?!! also set the idle screw higher because of this of course) so its totally reasonable to assume none of the settings on the pump are where they should have been.
  
  Ive got my timing set to exactly 1.00mm as per recommended "performance" settings. Stock setting for my engine should be 0.92mm +-.05
  
  Mileage is averaging 9-9.5 Lts\100km (26-24MPG).
  
  I was told in the German forums Setting my timing back to stock settings would help cut back on smoke but i haven't had time to try this yet.
  
  Tips suggestions? Thanks guys!
  
• #1 by libbydiesel on 31 Jan, 2020 16:35
• Setting the timing back might transform your smoke to be more gray but it won't reduce it any.  Retarding the timing will actually increase the amount of smoke as the fuel that is injected will have less time to burn before the end of the power stroke and the exhaust valve opens.
  
  Yes, you can reduce the amount of low rpm off-boost black smoke.  Performance will suffer some, though.  To do so, you need to think of it a bit backwards.  You want to increase the effect of the boost fuel enrichment so that on boost and off boost max fuel is similar and then turn down the max fuel.   
• #2 by BajaVWCamper on 31 Jan, 2020 18:36
• Makes sense. Lower the max and just increase the boost fuel... Now how do i particularly do that?... screw the turbo boost LDA arm to give more? Mind I have a JX turbo Diesel so the turbo boost is not a top-down diaphragm on top of the pump like on the Jettas, my LDA is mounted sideways on front of the pump (on the fuel line output side) that actuates a arm on top of the pump.
• #3 by libbydiesel on 31 Jan, 2020 22:53
• I'm familiar with the JX pump but have not had much experience trying to tune it.  The boost enrichment actuator has an adjustable rod and has an adjustable stop.  The shaft that gets rotated by the actuator has a cam on it which allows the added fuel under boost.  Adjusting the stop position and the rod length will change the position of the came for a given boost pressure.
• #4 by BajaVWCamper on 01 Feb, 2020 11:52
• Why didn't I think of that?! thanks a bunch!! I'll give it a shot
  
• #5 by libbydiesel on 01 Feb, 2020 19:22
• While you're at it, hook up a hand pump to your boost fuel actuator and pump ~10 psi into it to make sure it is functioning properly.  Your description of excessive fuel at low rpm and no boost sounds like it might not be. 
• #6 by BajaVWCamper on 23 Feb, 2020 04:38
• Hi again. Quick question. While at idle should moving the boost enrichment actuator change anything(engine speed)?
  I have screwed it's adjustment down somewhat already but I noticed it makes no difference while the engine running at idle whether I turn it up or down.
• #7 by BajaVWCamper on 23 Feb, 2020 10:09
• So upon further testing i have noticed the boost enrichment actuator lever makes no difference at all!
  The LDA can is working fine and opens up all the way under boost but regardless of the enrichment lever being full closed or full open it makes no difference in power. So im assuming it must be an internal pump problem.
  
  any tips or suggestions?
• #8 by libbydiesel on 23 Feb, 2020 12:01
• It is possible that someone installed the JX pump top onto a non-turbo base pump.  That can be done and will work fine, but there is a pin pressed into the side of the pump that *must* be cut short or the situation you describe will occur.  Post some closeup pics of the pump especially showing the seam between the main body of the pump and the top. 
• #9 by BajaVWCamper on 23 Feb, 2020 12:39
• 
  This is The only picture I have at hand right now
  
  Is the LDA boost function totally Independent from the smokescrew? (ie can i theoretically open the smoke screw higher than the LDA boost lever will boost?)
  
  I cant seem to find a solid answer to the question about the LDA boost lever. Does it add more fuel from where the smokescrew is set or does it operate totally Independently from the smokescrew?
• #10 by BajaVWCamper on 24 Feb, 2020 15:20
• And the rest 
  
  
  
  
  
• #11 by BajaVWCamper on 24 Feb, 2020 15:22
• is i theoretically possible that the smokescrew is so rich that the LDA lever is having no effect?Or regardless of how far the adjustment screw is the LDA lever should give it even more fuel?
• #12 by libbydiesel on 24 Feb, 2020 19:23
• I do not think so.  I believe that, when functioning properly, the LDA will always reduce fueling when off boost regardless of the max fuel screw position (I assume that is what you mean by smoke screw). 
• #13 by BajaVWCamper on 25 Feb, 2020 03:01
• Yes maxfuelscrew = smokescrew.
  I probably got to take my top cover off and have a look inside then. Thanks for the info though!