VWDiesel.net The IDI, TDI, and mTDI source.
Engine Specific Info and Questions => IDI Engine => Topic started by: Toby on July 12, 2010, 02:55:33 pm
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What is the procedure for adjusting transfer pressure in the IP? What does this adjustment do? It looks like the transfer pressure increase advances the pump timing, but increased performance on a diesel comes with retarded timing. So what gives?
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There is a thread about Inj Pump pressure and how to adjust it - what pressure ranges are desirable, etc... in the FAQ section.
It might be what you're looking for.
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I have looked and can't find it. Perhaps it is among the myriad of dead links. If you could point me to it I would be very appreciative.
Jason
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I have looked and can't find it.
I can't find it on here either.
Thinking now it was actually on vwdiesel.net forum
Because Hagar was a contributor involved with it, and he doesn't post on this site. I read all over the place from time to time.
Libbybapa was also a contributor.
Its a very long thread of some good reading.
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http://www.vwdieselparts.com/forum/viewtopic.php?t=5936 (http://www.vwdieselparts.com/forum/viewtopic.php?t=5936)
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Toby you would have never found that without Vince stepping up.
lmao @ myself
I'm really going to be a mess after a few more years of this growing older every day crap. Anyone seen my car keys ?
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I have two of the old GTD's, the transfer pressures do go out of whack over time, one was about 80% of what it should be at 1000rpm and the other 60%, yes it was horrible.
Below are the pump pressures I use. At least as much as can be deciphered from a copy of the Bosch technician book on the forum. The pump settings by Hagar seem a bit different, unfortunately increasing the pressure is MUCH easier than dropping it again if you whacked the pressure regulator too hard. It is VERY sensitive. My injector nozzles were tempered sky blue, so I feel Hagers settings are too fierce. Have fun.;) It is like adjusting a Swiss watch with a lump hammer.
my best guesses for the 1.6 TD's are as follows...
36-46psi@1000rpm, 67-75psi@3000rpm, 94-103psi@4500rpm,
these are engine rpm's. Google "hagar" and "smileage" for how to check the pressures.
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Increased performance does not come from retarded timing on a diesel. Static timing advanced slightly beyond the stock setting will typically give better performance and fuel economy.
Really? What do you think happens when you use the so called "Euro spec" IP timing of .105 mm? (Or whatever you magic spec is.) You are measuring how far the IP piston has traveled down the bore on the injection stroke. A setting of .105 is .030 mm BEHIND .085 mm. All of this is at TDC, remember. The pump with the .105 piston position at TDC will start and complete its job later than than the .085 mm pump.
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and to think, this dude says he is a GM diesel master..
sad you gotta have a group of VW guys show you whats what. haha...
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You need to watch the dial indicator more closely. The plunger is coming UP not down at TDC. And it continues up as the motor rolls past TDC.
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Yup, coming up, as in pushing in. So a setting of 1.00mm means the plunger has pushed in 1.00mm by TDC.... a setting of 0.80mm means it's only pushed in to 0.8mm by TDC.
In order for the pump to have pushed in 1.0mm by TDC it would have to start fuel delivery earlier than a pump set to 0.80mm...the very definition of "advanced" timing. ;)
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Not so. Watch your dial indicator. On the pump stroke the plunger is moving toward the dial indicator. Not way from it.
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We agree... it's moving towards the dial indicator, to the right in this picture:
(http://i197.photobucket.com/albums/aa85/vwaldon/VE_cross_sectionlarge.jpg)
The plunger moving to the right, towards the dial indicator, forces fuel thru the centre of the plunger into the delivery valve and eventually the injector, until the pressure is released by the control sleeve. Here's a closer look:
(http://i197.photobucket.com/albums/aa85/vwaldon/VEpumpcrosssectioncloseup.jpg)
So, an plunger that has moved 1mm to the right by TDC has started delivering fuel earlier than a plunger that has only moved 0.8mm to the right by TDC.
Ergo: a pump setting of 1.0mm is advanced over a pump setting of 0.8mm.
It's the hole up the centre of the plunger that sometimes confuses folks... the plunger is moving opposite towards the way you would think it needs to go to push fuel... but it's making the right hand side of the chamber smaller and so fuel travels up the centre in the opposite direction to the plunger and into the delivery valve ;)
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its just like gasser ign timing... just without the timing light and degrees of advance.
but why are we arguing that more timing is retarded, not advanced?
if you move the pump towards the engine, it advances the timing. makes it squirt sooner.
if you move it away from the engine, it retards it, makes it smokey, and gives you tons of useless boost.