[Vwdiesel] silly Diesel dances

[gary]

I have this this on a local friends car.

He came to me with a 98 Jetta. Complained of poor mileage, poor
acceleration, limited top end.

Put the VAGCom on it and it was low off the graph. I instinctively
attempted to advance it and it would do as yours... jump from either too
advanced to too retarded.

After much tinkering and swearing, I ended up moving the pulley 2 teeth
to further advance the timing. FINALLY! A steady timing reading, low
below the graph, but steady and on the page. Made the appropriate
mechanical adjustment, and timing is now just above middle and steady.

Just note, the difference between the lower end of the graph and the
upper end is only a pencil-line width of movement.

I may be mistaken, but when in "TDI Timing" mode, it removes all ECU
advancement, basically makes it go full retard.

Before trying the above, go into VAGCom, look at measuring blocks(The
channel that shows requested and actual timing in degrees, ch4?) See
where req vs actual says, and then the % duty cycle.

If the actual is retarded compared to req, and especially if the duty
cycle % is really high, then the pump is very retarded.


-Gary


On Tue, 2005-05-03 at 23:43 -0500, Shalyn Shourds wrote:
> Finally, this afternoon, I got to do the silly dance you do in the 
> driveway when the car finally starts.  I got the TDI to fire up after 
> months of lousy stuff happening. 
> 
> Unfortunately, all is not well.  I can't time it for some reason.  Last 
> time, it was pretty easy.  I got VAG-COM up, heated up the engine, 
> checked the timing, adjusted about a half-dozen times, and everything 
> was fine.  This time, I spent two hours trying to get it to sync up and 
> it just would not do.  It ran fine just before I started trying to 
> adjust it, but now it completely fills my garage with unburned fuel from 
> the tailpipe.  I also noticed that unlike the last time (at least that 
> I've noticed), when I'm staring at group 000 and I hit the button on the 
> lower left (memory and fatigue....) to get to the "TDI Timing" button, 
> the engine almost dies and it starts spewing smoke.  When I finally get 
> to the screen with the graph, it tells me that the timing is too 
> retarted or too advanced to graph no matter what I do adjustment-wise.  
> When I take it closer to the "right" range, it starts to wander from 
> "Too Retarded to Graph" to "Too Advanced to Graph" and _REALLY_ starts 
> to smoke.  Shame it's not like the old cars; I'd just tighten the 
> injection pump mounting bolts and be happy.  Doesn't work like that on 
> this one, unfortunately. 
> 
> Anyone know what hitting that button does to the engine?  I get a CEL, 
> it starts running lousy, and it fills the garage with unburned fuel 
> smoke.  Any other great ideas would be really appreciated.  I'd thought 
> I'd be getting it inspected tomorrow.  Guess not. 
> 
> It is, however, running just well enough to have a tragic accident 
> involving a lake, a train, and a suspicious engine fire. 
> 
> -Shalyn
> 
> 
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