diesel flywheel timing marks

[TylerDurden]

Pop pressures gotta be spec to get spec dial readings.

(Just because the sticker said 10 degrees in 1979, doesn't mean every other year was the same. ME and MF engines have the same pop pressures and camplates but the timing spec is different.)

[srgtlord]

I wonder if the different timing specs was to match the pollution requirements that changed from year to year?

[libbydiesel]

(Just because the sticker said 10 degrees in 1979, doesn't mean every other year was the same. ME and MF engines have the same pop pressures and camplates but the timing spec is different.)

CK ('79 diesel), ME and MF injectors all have very different pop pressures.  Where have you found that VW released a different spec in degrees BTDC for those three engines?  Have you compared the camplates from those three pumps?

[libbydiesel]

CK - 120-130 bar
ME - 130-138 bar
MF - 155-163 bar

I find they run MUCH smoother if you get all four injectors within 1 bar of each other.

[libbydiesel]

I assume it puts a incremental delay into the firing of the strobe light as you push the advance button. But it must know when and how much of a delay to put in based on calculation from RPM.

One degree adjustment might delay strobe by 1/720 pulse interval. Two crank rotations per pulse...

You are correct about that.  Thanks.

[TylerDurden]

You're right on those pops... I don't know where I saw the ME and MF grouped @ 135 with the 1V @155. 

I have measured the camplates.

[libbydiesel]

(Just because the sticker said 10 degrees in 1979, doesn't mean every other year was the same. ME and MF engines have the same pop pressures and camplates but the timing spec is different.)

Where have you found that VW released a different spec in degrees BTDC for those three engines?

I have measured the camplates.

You found the camplate from the '79 (1.5) to be exactly same as the ones from the non-turbo and turbo 1.6 pumps?  I haven't yet measured the camplate for the 1.5 but find that information startling.  Did you measure both the overall height and the shape?  What method of measuring did you use?  Did your method account for placement of the start, max height and end of the humps relative to the pin in the camplate?

[ORCoaster]

What you need to know about the chart I share is that is for my IP, rebuilt after gaskets started cracking.  I have run WVO through it and the pressure is at 43 psi at idle.  I am not sure why the lower end of the pulse adapter isn't getting down to the 12 mark.  That is where I was expecting it to go.  I even measured it several times and really retarded the pump to see if I could get it to go lower but no dice. 

So take it with a big grain of sea salt and kelp.  I only can chart the numbers I measured.  Not going to skew data like some researchers just to make a pretty line.  That is why the trend line is in there.  But again it does seem odd to cross the Y axis on the left side at the wrong point. 

I have no idea what my pops are, and it is like really, really bothering me.  Might be time to spend some coin and get them done again.  But I am spending it on some welding of the exhaust pipe instead.  There is always something on a VW that will take your money to make it run. 

[libbydiesel]

I have found that advanced to the point that it runs poorly and retarded to the point that it runs poorly, the movement of the pump and the strobe position is directly related.  In other words, if I rotate the body of the pump a degree, the pulse moves a degree.  This is advanced to 20ish BTDC and advanced to TDCish.  I haven't gotten the protractor out, to make sure of the 1:1 relationship but it sure seems that way.  I've seen this consistent behavior on 30ish pumps.  Orcoaster, it sounds like you have some weirdness going on with either you pulse adapter, your timing light, your pump or your injectors.

[ORCoaster]

The injectors are my bet.  The other three tested out fine.  The injectors have not been rebuilt to my knowledge but they did come off a head of good reput.  So saving pop cans and beer bottles for the day I can have the coin to take them up to Portland or Eugene for a redo.

Or buy on line and hope they are within a few bars of one another.  That is why I lean to the shop side of doing that work.  I can tell them what I want and pay accordingly.  On line, crap shoot as far as I can tell.  Anyone have good luck with the unknown supplier on line? 

[92EcoDiesel Jetta]

I have found that advanced to the point that it runs poorly and retarded to the point that it runs poorly, the movement of the pump and the strobe position is directly related.  In other words, if I rotate the body of the pump a degree, the pulse moves a degree.  This is advanced to 20ish BTDC and advanced to TDCish.  I haven't gotten the protractor out, to make sure of the 1:1 relationship but it sure seems that way.  I've seen this consistent behavior on 30ish pumps.  Orcoaster, it sounds like you have some weirdness going on with either you pulse adapter, your timing light, your pump or your injectors.

Maybe I am having similar issues. On your timing light, do you get correct, rock steady RPM reading? I don't on mine, if I switch from strobe to RPM, I get a good reading for a while and it may then double in value and sometimes disappears (goes to zero). It does not affect the strobe, which always flashes, and does not seem to matter if in 2 or 4 cyl mode (for strobe). In strobe mode, do you find a difference whether in 2 or 4 cyl ?

Of the 30ish pumps you have adjusted timing on, they were all able to be adjusted to 12 deg BTDC without fuss? Of those 30ish engines, did you measure injector pop pressures and internal IP fuel pressure before doing the diesel pulse adapter adjustment?

What kind of prep do you do to the injector line before putting the piezo clamp on? How tight or loose do you adjust the clamp and is it very sensitive to adjustment?

[libbydiesel]

The strobe flashes are usually not perfectly 100%, but very close to it.  RPM is rock solid on mine.  I believe I have the same timing light model as in your videos.  My pulse adapter is Snap-On and an earlier model than the one they currently sell.  Just to be clear, the 2/4 button is 'cycle' not 'cylinder'.  The number of strobe flashes will be the same either way, but the rpm and advance will be half/double if set wrong.  If both pump and injectors are dual stage it may need to be set to 2, but I can tell visually if the strobe is flashing at both the flywheel 0 and 180 or just at the 0.

The injection line must be clean and shiny.  If it isn't, the pulse reading will be very erratic.  If the lines need it, I sand a patch of line right by the #1 injector for both the pickup and the ground connection.

All the pumps I have dealt with have adjusted without undo fuss.  I have not adjusted them on 30 different engines.  The vast majority have been installed on eithe my AHU mTDI Vanagon or my 1.6TD Rabbit.  I have checked the first stage on the AHU injectors and have callibrated the injectors on the 1.6TD so they are very close in break pressure.  Many of those pumps were new and so the internal pressure did not require adjustment.  I have adjusted the internal pressure when needed, but do not find that it affects the idle timing unless it is too high because at idle pressure, the advance plunger should be resting on its stop.   

[92EcoDiesel Jetta]

Yes "cycle", not "cyl", which makes no sense. I did set the injector pop and internal pump pressures to spec a few years ago. I will check them again and clean the inj. line better and try again. I don't think the issues I am having are timing light related.

Last time I tried to use my pop tester (Ford Rotunder commercial unit), I couldn't get it primed. Replaced the o-ring and still wouldn't prime. It has a big fuel reservoir on the base and must work against gravity to prime itself. I will try to rig up an external reservoir above the pump to gravity feed it and see if that works.

[TylerDurden]

Did you measure both the overall height and the shape?  What method of measuring did you use? 

http://www.vwdiesel.net/forum/index.php?topic=33196.0

[libbydiesel]

That is a nice way to test the camplate.  It does show the NA and TD camplates to be the same.  It does not show anything about the 1.5 camplate.  Have your comments in this thread and elsewhere implying/stating that VW used different start-of-injection timing specs been solely based on the erroneous belief that the break pressures were the same between the 1.6 TD and NA engines?