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Author Topic: Diesel Pulse Adapter Info Thread  (Read 77381 times)

Reply #30February 10, 2014, 11:56:15 pm

TylerDurden

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Re: Diesel Pulse Adapter Info Thread
« Reply #30 on: February 10, 2014, 11:56:15 pm »
What's the white smoke when timing is retarded? Unburnt fuel methinks...

So, despite a hot injector and a flame-front from initial combustion, the flame goes out and unburnt fuel goes out the tailpipe?
(fuel heating from compression in the hardlines is negated upon release and atomization methinks)


TheMan53, you are following my drivel correctly, compression vs temperature is generally a constant, but the leakdown of bad rings makes it more tricky. Consider the recent topic on push-starting vs cranking.... push starting can spin the engine fast enough to reach autoignition before leakdown and before the air-charge cools on the metal surfaces. Slow crank a cold engine with low compression... no autoignition, no worky. Conversely, high compression allows earlier injection timing, earlier combustion that can continue across TDC until the fuel is entirely spent.



Reply #31February 11, 2014, 12:33:21 am

libbydiesel

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Re: Diesel Pulse Adapter Info Thread
« Reply #31 on: February 11, 2014, 12:33:21 am »
There is always some combustion lag and I never tried to say there wasn't.  What I did try to say is that once normal operating temperature is reached the difference in time between start of injection and start of combustion on a fresh engine vs. one that is nearing the bottom end of spec is not significant.  
« Last Edit: February 11, 2014, 12:36:27 am by libbydiesel »

Reply #32February 11, 2014, 12:36:04 am

theman53

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Re: Diesel Pulse Adapter Info Thread
« Reply #32 on: February 11, 2014, 12:36:04 am »
What's the white smoke when timing is retarded? Unburnt fuel methinks...

So, despite a hot injector and a flame-front from initial combustion, the flame goes out and unburnt fuel goes out the tailpipe?
(fuel heating from compression in the hardlines is negated upon release and atomization methinks)


TheMan53, you are following my drivel correctly, compression vs temperature is generally a constant, but the leakdown of bad rings makes it more tricky. Consider the recent topic on push-starting vs cranking.... push starting can spin the engine fast enough to reach autoignition before leakdown and before the air-charge cools on the metal surfaces. Slow crank a cold engine with low compression... no autoignition, no worky. Conversely, high compression allows earlier injection timing, earlier combustion that can continue across TDC until the fuel is entirely spent.



I cannot count that fast.

Reply #33February 11, 2014, 07:30:43 am

TylerDurden

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Re: Diesel Pulse Adapter Info Thread
« Reply #33 on: February 11, 2014, 07:30:43 am »
Here's another way to look at it:
Without the cold-start advance of 5o (crank), a cold engine might run kinda crappy... that's from combustion lag due to low air temperature, IMO. The cylinders reach autoignition point later, and fuel goes out the tailpipe.

A 250psi engine might run pretty good with 5o advance of static timing. Insignificant?... Maybe not.

Reply #34February 11, 2014, 09:14:18 am

libbydiesel

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Re: Diesel Pulse Adapter Info Thread
« Reply #34 on: February 11, 2014, 09:14:18 am »
Your imagination is, in a way, interesting...  Your premise seems to be that, based on your imagination, compression that is half of spec might affect injection lag on a fully warmed up engine, making a more advanced timing spec beneficial.  If a more advanced timing spec might be beneficial on a vastly out of spec engine, then a pulse adapter, in all cases, is a worthless tool and everyone (seig heil) should (moral imperative) ditch all non-subjective timing tools and embrace hillbilly timing their engines.

If you want to argue the uselessness of a tool that you've never used on the basis that it can't optimize a thoroughly worn out engine, that doesn't seem either logical or useful to anyone.  Although, it is, arguably, entertaining.  If you have a particular beef against diesel pulse adapters, then I can probably help you imagine even more potential issues...  Let's consider the dynamic advance and case pressure.  If someone installs an IN bolt in the Out bolt location, the vane pump is worn out, the pressure regulator is whacked out of adjustment and the dynamic advance piston bore is gouged, the dynamic advance will not work correctly.  With the dynamic advance not doing it's thing, if you use a pulse adapter to set the timing at idle, then the timing will be progressively more and more off as the rpms increase.  In that case, hillbilly timing the engine so that it is timed properly for cruising rpms will return better performance and much better fuel economy.  When running a worn out injection pump with no case pressure and jacked dynamic advance, a pulse adapter is the wrong tool for the job...  What about injector pop pressure?  Maybe that affects the start of combustion even more than compression.  You might imagine that larger droplets of fuel take longer to ignite that a super-fine mist.  In that case, dropping compression would reduce injection lag as the pressure difference between pop pressure and cylinder pressure will affect atomization and a lower cylinder pressure will result in a greater pressure differential.  You could argue that with injector pop pressure 1/2 of spec, you imagine the tool would also be ineffective.  How about if the atmosphere had a reduced oxygen content.  That also might make the tool less useful.  You might imagine that if you were on a different planet then a pulse adapter wouldn't be nearly as optimal for timing your 1/2 compression, 1/2 injector pop pressure VW diesel.  What if you were running it on unicorn piss?  Everyone knows that the BTU content of unicorn piss is much higher than no. 2 diesel but the viscosity is proportionately lower.  How do you imagine that running on unicorn piss would affect the usefulness of a pulse adapter for timing your 1/2 compression, 1/2 pop pressure VW engine with worn out injection pump, while living on the planet Zuark with it's reduced oxygen atmosphere? 
« Last Edit: February 11, 2014, 09:58:34 am by libbydiesel »

Reply #35February 11, 2014, 09:58:29 am

theman53

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Re: Diesel Pulse Adapter Info Thread
« Reply #35 on: February 11, 2014, 09:58:29 am »
I think you have made your point. This tool seems very useful and needs discussion for those of us who don't have one yet.

Guys, I think this has enough information for us to get the basics on how it works now. If you don't think the thread does, why don't you wait a few days before firing it up again. There is nothing bad here...yet...I would like it to stay that way and we all be friends. So lets find some common ground and come back to this if we have to.


Reply #36February 11, 2014, 12:37:26 pm

92EcoDiesel Jetta

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Re: Diesel Pulse Adapter Info Thread
« Reply #36 on: February 11, 2014, 12:37:26 pm »
This is very entertaining! I think everyone loves to have a diesel pulse adapter but don't want to spring the $$$ for one just yet without fully understanding what it can and cannot do. Since you have not answered my question from before (copied below), can I assume it is not from the SnapOn diesel pulse adapter manual?


Quote from: libbydiesel on February 10, 2014, 11:49:01 AM
The piezo adapter fires at the start of injection.  The micro-expansion of the metal line is what charges the crystal pickup and it fires it's pulse when the line starts to relax which is at the actual start of injection which precisely coincides with needle lift.  Yes, the piezo pickup DOES detect needle lift very accurately.

......................

Is this info from the SnapOn pulse adapter manual? It would be interesting to verify  with an oscilloscope if the injection line pulse coincides with needle lift. Wouldn't be too difficult to set up on an engine with a needle lift injector. I think all TDI's have one. IIRC needle lift is on #3 cyl? Why did VW do that instead of on #1?

Your imagination is, in a way, interesting...  Your premise seems to be that, based on your imagination, compression that is half of spec might affect injection lag on a fully warmed up engine, making a more advanced timing spec beneficial.  If a more advanced timing spec might be beneficial on a vastly out of spec engine, then a pulse adapter, in all cases, is a worthless tool and everyone (seig heil) should (moral imperative) ditch all non-subjective timing tools and embrace hillbilly timing their engines.

If you want to argue the uselessness of a tool that you've never used on the basis that it can't optimize a thoroughly worn out engine, that doesn't seem either logical or useful to anyone.  Although, it is, arguably, entertaining.  If you have a particular beef against diesel pulse adapters, then I can probably help you imagine even more potential issues...  Let's consider the dynamic advance and case pressure.  If someone installs an IN bolt in the Out bolt location, the vane pump is worn out, the pressure regulator is whacked out of adjustment and the dynamic advance piston bore is gouged, the dynamic advance will not work correctly.  With the dynamic advance not doing it's thing, if you use a pulse adapter to set the timing at idle, then the timing will be progressively more and more off as the rpms increase.  In that case, hillbilly timing the engine so that it is timed properly for cruising rpms will return better performance and much better fuel economy.  When running a worn out injection pump with no case pressure and jacked dynamic advance, a pulse adapter is the wrong tool for the job...  What about injector pop pressure?  Maybe that affects the start of combustion even more than compression.  You might imagine that larger droplets of fuel take longer to ignite that a super-fine mist.  In that case, dropping compression would reduce injection lag as the pressure difference between pop pressure and cylinder pressure will affect atomization and a lower cylinder pressure will result in a greater pressure differential.  You could argue that with injector pop pressure 1/2 of spec, you imagine the tool would also be ineffective.  How about if the atmosphere had a reduced oxygen content.  That also might make the tool less useful.  You might imagine that if you were on a different planet then a pulse adapter wouldn't be nearly as optimal for timing your 1/2 compression, 1/2 injector pop pressure VW diesel.  What if you were running it on unicorn piss?  Everyone knows that the BTU content of unicorn piss is much higher than no. 2 diesel but the viscosity is proportionately lower.  How do you imagine that running on unicorn piss would affect the usefulness of a pulse adapter for timing your 1/2 compression, 1/2 pop pressure VW engine with worn out injection pump, while living on the planet Zuark with it's reduced oxygen atmosphere? 

Reply #37February 11, 2014, 12:54:04 pm

libbydiesel

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Re: Diesel Pulse Adapter Info Thread
« Reply #37 on: February 11, 2014, 12:54:04 pm »
This is very entertaining! I think everyone loves to have a diesel pulse adapter but don't want to spring the $$$ for one just yet without fully understanding what it can and cannot do. Since you have not answered my question from before (copied below), can I assume it is not from the SnapOn diesel pulse adapter manual?


Quote from: libbydiesel on February 10, 2014, 11:49:01 AM
The piezo adapter fires at the start of injection.  The micro-expansion of the metal line is what charges the crystal pickup and it fires it's pulse when the line starts to relax which is at the actual start of injection which precisely coincides with needle lift.  Yes, the piezo pickup DOES detect needle lift very accurately.

......................

Is this info from the SnapOn pulse adapter manual? It would be interesting to verify  with an oscilloscope if the injection line pulse coincides with needle lift. Wouldn't be too difficult to set up on an engine with a needle lift injector. I think all TDI's have one. IIRC needle lift is on #3 cyl? Why did VW do that instead of on #1?

I read up on the function of the diesel pulse adapter before purchasing mine several years ago.  I do not recall if the Snap-on manual specifically includes that info.  At the risk of sounding redundant, if you doubt it, then I would welcome you to do your own research.

I happen to have a TDI (actually three), a pulse adapter and an oscilloscope but am not inclined towards accommodating your test for two reasons.  The first is that it is a waste of my time as I already did do my research on the function of the piezo pickup and the diesel pulse adapter and have no reason to doubt what I previously read.  The second is that I have not read up on the function of the pintle lift sensor and how it produces it's signal and so hooking up the scope to it would not give me any helpful info.  

I did previously give my best best guess as to why they used #3.  Which injector sends the signal to the ECU is irrelevant provided the program accommodates for which one is sending the signal.  The metal lines all have to be the same length and maintaining that equal length with a tall #1 injector would be harder than doing so on the #3 which is closest to it's delivery valve.

Reply #38February 11, 2014, 01:22:20 pm

92EcoDiesel Jetta

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Re: Diesel Pulse Adapter Info Thread
« Reply #38 on: February 11, 2014, 01:22:20 pm »
I agree that with an ECU, which injector to put the needle lift on does not matter. I like your explanation that it's easier to do on #3 since it's closest to the delivery valves.

I think the needle lift sensor is a variable reluctance type. If it has 2 wires and is between 30 to 1500 ohms, it most likely is VR. If it has 3 wires, it is hall effect. Wouldn't be hard to set up an O-scope to look at the outputs of the needle lift and piezo of the pulse adapter dual trace and see their relationship. If I have all the pieces, I would definitely do the test.

This is very entertaining! I think everyone loves to have a diesel pulse adapter but don't want to spring the $$$ for one just yet without fully understanding what it can and cannot do. Since you have not answered my question from before (copied below), can I assume it is not from the SnapOn diesel pulse adapter manual?


Quote from: libbydiesel on February 10, 2014, 11:49:01 AM
The piezo adapter fires at the start of injection.  The micro-expansion of the metal line is what charges the crystal pickup and it fires it's pulse when the line starts to relax which is at the actual start of injection which precisely coincides with needle lift.  Yes, the piezo pickup DOES detect needle lift very accurately.

......................

Is this info from the SnapOn pulse adapter manual? It would be interesting to verify  with an oscilloscope if the injection line pulse coincides with needle lift. Wouldn't be too difficult to set up on an engine with a needle lift injector. I think all TDI's have one. IIRC needle lift is on #3 cyl? Why did VW do that instead of on #1?

I read up on the function of the diesel pulse adapter before purchasing mine several years ago.  I do not recall if the Snap-on manual specifically includes that info.  At the risk of sounding redundant, if you doubt it, then I would welcome you to do your own research.

I happen to have a TDI (actually three), a pulse adapter and an oscilloscope but am not inclined towards accommodating your test for two reasons.  The first is that it is a waste of my time as I already did do my research on the function of the piezo pickup and the diesel pulse adapter and have no reason to doubt what I previously read.  The second is that I have not read up on the function of the pintle lift sensor and how it produces it's signal and so hooking up the scope to it would not give me any helpful info.  

I did previously give my best best guess as to why they used #3.  Which injector sends the signal to the ECU is irrelevant provided the program accommodates for which one is sending the signal.  The metal lines all have to be the same length and maintaining that equal length with a tall #1 injector would be harder than doing so on the #3 which is closest to it's delivery valve.

Reply #39February 11, 2014, 05:10:03 pm

Toby

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Re: Diesel Pulse Adapter Info Thread
« Reply #39 on: February 11, 2014, 05:10:03 pm »
I think you guys are working from a bunch of unfounded assumptions and confusing some different concepts.

First of all being able to "set" the timing with a fancy piezo sensor or a luminosity probe only gives you a more repeatable way to set the timing at the same point. This does not correlate to the "best" setting in any way.

If you think that you have found the holy grail if injector timing you are deluding yourself. I have played with the IP timing on close to 100 IDIs over the years and I can tell you that each one has its own sweet spot. I can also tell you that when you find the sweet spot it will run better that it ever has before. Setting with the IP dial indicator or the luminosity probe won't find the sweet spot. However, once you find the sweet spot, it can help you repeat the setting ON THAT ENGINE. The sweet spot on the next engine is most likely somewhere else. In other words, you need to find the sweet spot on one particular engine and then find out where it is set with you timing tool, what ever it is. Then you can always go back to it.

As I said before, its all relative....

Now, you can piss and moan about worn engines and pumps lousing up your perfect world of IP timing, but we live in the real world. A world where compression is uneven, pop pressures are uneven, internal leakage in the head differs. You holy grail of IP timing will not help you there, until you find the sweet spot and figure out where your tools says it is.

FWIW IDIs will start fairly well at 250 psi compression as long as it doesn't get too cold. Say below 45*F. There were also lots of then running around with horrible injectors.: widely varying pop pressures, squirting rather than spraying, sticking pintles,etc. And they were still running around getting 35 mpg.
So the idea that we are only dealing with things as they should be is a fallacy.

In addition, if you think that air temp, spray pattern, and compression do not greatly effect the start of combustion you need to pay a bit more attention. It is quite common to see a diesel with a good glow plugs but lower compression in one cylinder to carry that hole on start up for 30 seconds or a minute in very cold weather. So it seems that the delta here between compression temps is significant at any given point in the cycle.

FWIW I used to have the Snap On luminosity probe set up, but I sold it years ago, because it was not telling me what I needed to know in terms of making the cars that I was working on run better. I wish I still had it to play with for hobby stuff. I piezo set up would be the most fun, though.

 

Reply #40February 12, 2014, 12:27:34 pm

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Re: Diesel Pulse Adapter Info Thread
« Reply #40 on: February 12, 2014, 12:27:34 pm »
I see the benefit of the pulse adapter over the dial indicator, and I also see how different engines in different states will have different sweet spots, making setting 'by the book', with either method above, of limited value. But, how close is the book value to the typical sweet spot?

Toby, in the 100's that you've timed up, was the sweet spot always pretty close to the by the book setting, or could it be different by a fair margin? What range from extreme to extreme are we looking at?

And again, what output would you see if you monitored the needle lift and crank sensor? Simply a voltage spike?
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Reply #41February 12, 2014, 12:43:09 pm

libbydiesel

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Re: Diesel Pulse Adapter Info Thread
« Reply #41 on: February 12, 2014, 12:43:09 pm »
But, how close is the book value to the typical sweet spot?

In testing a wide variety of engines/pumps/injectors with the diesel pulse adapter, provided the dynamic advance is working properly, the 'sweet spot' is within 1/2 of 12BTDC with my setup.  That wide array of engines/pumps/injectors includes both fresh and well-worn VW IDI, VW TDI and Mercedes IDI engines with both fresh and well-worn pumps/injectors.  On the VWs, I have also checked the plunger lift on several setups in order to find what the plunger lift measurement coincides to with a particular pump or set of injectors.  The plunger lift setting can vary fairly significantly but the 'sweet spot' with the pulse adapter does not. I also recently used the pulse adapter to time a freshly rebuilt 1.6TD injection pump on a good condition engine with freshly rebuilt injectors set to spec opening pressure.  Because I was sending the pump and injectors to a friend who does not have a pulse adapter, I tested the plunger lift with the dial indicator so he could repeat it.  It came out to exactly 1.05mm which coincides conveniently with the VW spec.  Several years ago I did the reverse on another friend's engine.  We installed a freshly rebuilt injection pump with fresh injectors on his freshly rebuilt engine and then timed it using the dial indicator to 1.05mm.  I then checked his timing using the pulse adapter and strobe and it was precisely 12.

Reply #42February 12, 2014, 01:05:33 pm

monkey magic

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Re: Diesel Pulse Adapter Info Thread
« Reply #42 on: February 12, 2014, 01:05:33 pm »
Kind of what I expected really. So, setting by injection pulse timing is preferable to the dial indicator (we are trying to time injection after all, dial indicator isnt necessarily telling us this due to breaking pressure etc), and it gets it very near to the sweet spot. So using a device like this for initial setting, then testing (a la hillbilly/ norwegian dyno run etc) either side of initial setting would be the best way for us to time these mtdis up well.

The 1st time I set up an mtdi i messed with the timing a lot, using the dial. The 2nd time, i did it by ear and it runs fine. Id like to find that sweet spot for sure tho, and being able to measure with a device like this has to be the most convenient method.
« Last Edit: February 12, 2014, 01:10:46 pm by monkey magic »
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Reply #43February 12, 2014, 01:11:07 pm

bbob203

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Re: Diesel Pulse Adapter Info Thread
« Reply #43 on: February 12, 2014, 01:11:07 pm »
Hillbilly timing on MTDi engine i don't find as easy as an idi.
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Reply #44February 13, 2014, 09:36:09 am

theman53

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Re: Diesel Pulse Adapter Info Thread
« Reply #44 on: February 13, 2014, 09:36:09 am »
But, how close is the book value to the typical sweet spot?

In testing a wide variety of engines/pumps/injectors with the diesel pulse adapter, provided the dynamic advance is working properly, the 'sweet spot' is within 1/2 of 12BTDC with my setup.  That wide array of engines/pumps/injectors includes both fresh and well-worn VW IDI, VW TDI and Mercedes IDI engines with both fresh and well-worn pumps/injectors.  On the VWs, I have also checked the plunger lift on several setups in order to find what the plunger lift measurement coincides to with a particular pump or set of injectors.  The plunger lift setting can vary fairly significantly but the 'sweet spot' with the pulse adapter does not. I also recently used the pulse adapter to time a freshly rebuilt 1.6TD injection pump on a good condition engine with freshly rebuilt injectors set to spec opening pressure.  Because I was sending the pump and injectors to a friend who does not have a pulse adapter, I tested the plunger lift with the dial indicator so he could repeat it.  It came out to exactly 1.05mm which coincides conveniently with the VW spec.  Several years ago I did the reverse on another friend's engine.  We installed a freshly rebuilt injection pump with fresh injectors on his freshly rebuilt engine and then timed it using the dial indicator to 1.05mm.  I then checked his timing using the pulse adapter and strobe and it was precisely 12.

I am going to pull the trigger on this eventually, but I am wondering what affects an injection pump with the advance section modified would have? On these pumps that we new or rebuilt, did you have one with the advance section modded to give more dynamic advance into the pump? I ask as I have that Giles pump and that is where I am at with that.

 

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