Diesel Pulse Adapter Info Thread

[ORCoaster]

Nice summary and results.  I think we are learning something here about our pumps and age and equipment matching.  I would have not gone to 1.4 either.  But that is what it takes to get to the 12 degree mark where things seem to be designed to work best.

[vanbcguy]

Interesting!  I had read elsewhere that the Rover pump should be set at 1.45mm - which is pretty darn close to your measured 1.40mm.  Excellent!

[rbremiller]

Great info. Another 'confirmation'.

[smokeinmirrors]

 This experiment has made me see why people spend $$ on professionally tuned engine specific pumps. The fact that I lost bottom end power by moving the pump's max advance point closer to the sweet spot of the engine tells me that a pump with a slightly wider advance range would be a great improvement. Oddly though, from what I've seen the 300TDI engine that this pump was originally on doesn't redline very much lower than the VWs.

[vanbcguy]

Don't forget about the big "E" word - emissions. Advance causes NOx levels to rise. As a result the "factory" timing curve doesn't necessarily have as much advance built in to it as it would if performance was the only concern.

And yeah, this is exactly the point where a pro with an electronic pump calibration bench PLUS extensive experience with the engine in question becomes very very valuable. Or alternatively where suddenly the e-TDI starts to shine.

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[92EcoDiesel Jetta]

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I've found the pulse adaptor does not work very well past 1500rpm, and even....  you need to take into consideration the load on your pump when you check the timing, it's impossible to do at neutral, you have to drive the car at various rpm and load.

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Tintin, can you provide more details on this please? Is this 1500 rpm limit on any particular brand of pulse adapters, or all of them? Is this limit applicable to rpm measurements only, or strobe measurements, or both? And finally, why does it have this limitation? Is it due to the timing light, or the pulse adapter, or something else?

[vanbcguy]

Someone alluded above that the lines don't have time to relax properly between injection events at higher RPMs. The piezo clamp works based on physical changes to the line itself (it expands slightly when pressurized) so this is an easy one to imagine.

As to the second part (load) these pumps have load dependant timing. The amount of advance at say 2500 RPM with low load is not the same as when the accelerator is pressed down. So you can't really measure the actual timing under load with a strobe in neutral.

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[vanbcguy]

Finally used my pulse adapter on my engine today.  And yes I can confirm that the $50 TinyTach clamp works fine with the Snap-On box, so if you have a Snap-On box and don't want to pay them $300 for a new clamp the TinyTach one is great!  I found that the clamp did not work reliably at all near the pump, but works great when attached to the #1 line near the injector.

I actually dropped my timing back from 1.40 to 1.30 today as the clatter was overwhelming.  I think my great big .275 injectors have the same effect as advancing the timing a bit since the actual injection duration is probably extremely short versus stock nozzles - the entire injection event likely only takes a fraction of the time of stock .183 or whatever nozzles.  With my timing at 1.30 I read 8º advanced, so it was probably pretty darn close to 12º when I had it set to 1.40 initially.

[ORCoaster]

Yes!!!   That Tinytach clamp has to go towards the injector.  Now that you have it purring and have the two measurements mech dial and strobe degrees you can play around with it a bit.  With those big wide nozzles going I wonder if the fuel cycle is that much different than stock.  You build pressure against the needle same as stock before it pops right.  Still 130 or something BAR?  So the delivery time is still controlled by the pressure that way.  It would be the shut down time that would be different.  All that volume going through a bigger opening would do so much faster.  So the swirl time would be longer and the mix better.  Detention occurs when compression gets high enough to light it off.

Or am I in need of drink?
 

[vanbcguy]

Combustion begins with the pilot spray (the first "pop" of two stage injectors) and continues until all fuel is burned - if the injector sprays longer then you keep burning longer. There's not really any mixing time after injection, combustion starts as soon as the fuel hits the hot air. That's why the timing adjustment is so picky.



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[92EcoDiesel Jetta]

Finally used my pulse adapter on my engine today.  And yes I can confirm that the $50 TinyTach clamp works fine with the Snap-On box, so if you have a Snap-On box and don't want to pay them $300 for a new clamp the TinyTach one is great!  I found that the clamp did not work reliably at all near the pump, but works great when attached to the #1 line near the injector.

I actually dropped my timing back from 1.40 to 1.30 today as the clatter was overwhelming.  I think my great big .275 injectors have the same effect as advancing the timing a bit since the actual injection duration is probably extremely short versus stock nozzles - the entire injection event likely only takes a fraction of the time of stock .183 or whatever nozzles.  With my timing at 1.30 I read 8º advanced, so it was probably pretty darn close to 12º when I had it set to 1.40 initially.

Can you post a pic of the Tinytach piezo? Is the opening round or square? I picked up a used MAC Tools ET18DPM diesel pulse adapter. It looks like it's had very little use once I cleaned off the dust and dirt on the case. Manual still inside. Works fine on my Mercedes with nice and steady RPM and strobe readings but on my Jetta, it jumps all over the place. I am going to clean the #1 injector line better and remove the injector line clamps and see if that helps.

[ORCoaster]

I will try and pic one tomorrow if it isn't raining.  I want to do the compare and contrast thing with the two adapters I have.  Been trying for a month or more on that.  I have a Tiny Tach and it is working well and the clamp is right on top so pic be easy to do. 

[92EcoDiesel Jetta]

Can you also get a pic of what the 12 deg BTDC mark looks like on the flywheel? On my 92 Eco, it's  rectangular 1/8 x 1/2"  but does not look anything like the pic Fatmobile posted earlier.

[ORCoaster]

I think the tab you are looking at is the 12 degree one.  Sounds like what I have.  Didn't get to doing the compare and contrast thing.  Mom needed a drive to the Ocean, a walk and a pizza.  Will go grab a picture before the sun goes down.

[ORCoaster]

OK, here you go.  One from the top looking down then the 45 degree view from the end of the block and then sideways for a look at height above the injector nut.  This is on the #4 cyl just in case you are wondering.  RPM is RPM don't matter which one I am measuring on the block.  I can see in the photos that I never did clean the fuel lines before attaching the take off.  Hasn't been a problem either.