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Engine Specific Info and Questions => IDI Engine => Topic started by: citigolf on March 01, 2009, 05:59:49 am
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i have read the FAQ, does anyybody know of a more detailed "how to" on the Govener MOD. - pics would be good.
i dont want to take it apart till i know what im looking for
cherrs
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This is about what it should look like when you get it back together. I went with more shims about 1/4" worth. Leave the smallest = idle spring and the middle = intermediat spring alone. Just do the big one. You can't really see it but there is a little E clip that holds everything together. Once you put the shims in it is very hard to compress the spring and put the clip on. I did one by myself without tools and one with some tools and the wife...much easier.
(http://www.66rover.com/TDIswap/TDI%20Parts%20121307/slides/PICT1779.JPG)
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i can only see 2 springs??
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Its ABOUT what it should look like. It has been awhile since I have had it open. If I remember correctly the littlest spring isn't pictured and should be at the end where the floppy looking peice is. I know it is a technical term but the end on the right side of the peice.
Also if you do take it off scribe lines and take pictures of how the pump came apart, springs, arms, and basically anything to do with the top of the pump. That way you will be able to put it back the way it was and it will run correctly. If not it is a real guessing game.
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I have a complete how to if you want it. It's the best one i've found and I followed it, mine works great. PM.
please do share :D
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please do share
I second that!
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please do share
I second that!
Please. lol
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many thanks, but I would only shim the big one.
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not really, as they have different characteristics, the main idea of the governor is to create two different elongation VS force ramps.
shimming one of them changes only one of the ramps, that can be understood on the VE manual.
(or by working the governor by hand and feeling the different resistance profiles )
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correct if we're talking about static operation, I'll try to find a graphic of length VS force from the governor to illustrate.
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The spring seat has a clip under it, the main and intermediate springs have their own spring rate and allowed movement.
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As underpsi said the middle spring seat cant move...so shimming the main wouldnt be the same as shimming the intermediate the same amount.
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The spring seat has a clip under it, the main and intermediate springs have their own spring rate and allowed movement.
exactly!
As underpsi said the middle spring seat cant move...so shimming the main wouldnt be the same as shimming the intermediate the same amount.
correct
there are two (very)different spring rates on the governor, when pulled by hand the small one bottoms out long before the main starts to compress
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What does each spring control?
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The best way I've been able to get it together in my head is like this:
- Idle spring is pretty straight forward - idle speed is where the governor is balanced against the tension of the idle spring. As soon as you go above idle, the idle spring is fully compressed and no longer functional
- Main spring, also pretty straight forward - main spring is uncompressed until you start getting to around 4K RPM at which point it starts cutting fuel off very quickly
- Intermediate spring - this is the tricky one... Ever notice how you can hold a really precise RPM on your diesel really easily without too much trouble? My understanding is the Intermediate spring "cushions" the throttle. The actual control collar movements involved between full throttle and zero throttle are so tiny you really don't want a direct connection to your foot. If you look at how much total movement is allowed by the intermediate spring versus how far the actual accelerator linkage can pull on the entire works, your foot can easily override the intermediate spring.
My favorite video to wrap my head around all of this: http://www.youtube.com/watch?v=6j0vrfaXPmw
If you watch how much movement there is due to the idle spring, and how much movement there is due to the main spring, and the compare that to the intermediate spring you can see the intermediate spring really isn't costing any power, or at least nothing that you can't easily overcome by putting your foot down a little further. What I think it is doing is making drive-ability a lot better... I think in the normal driving range (1500 to 3000 RPM) the intermediate spring should be partially compressed. If you start going uphill a little and the RPMs drop a tad it's going to add fuel, likewise if you start going downhill a touch and RPMs increase without a corresponding change in where your foot is at it will cut fuel a bit... Just small amounts, enough so you don't really notice but you DO notice how much easier it is to keep the car going at a particular speed versus a "touchy" gas motor.
It's always tough to get my head around how the whole accelerator thing works on a VE pump... Your foot really isn't connected to anything other than a bunch of springs - the pump knows what it's doing far better than we do!
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Excellent post Vanbcguy... great description of a pretty complicated control system.
It's always tricky to balance power and drivability on a daily driver. I get the feeling that folks are tending to leave the intermediate spring alone and just mess with the main spring when doing the governor mod these days... and your explanation helped show why that might be the case.
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Thanks vanbcguy, as vince says a good explanation of how it works...
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wow, that was a masterpiece of a post! :D
I found what I was looking for: page 89 of the 1.5D SAE paper it explains what each spring does to the control collar VS rpm.
there is a difference thou, there are 5 springs:
-idle(part of the linkage) (500rpm to 1000rpm)
-intermediate (the really small one, outside the cage on the governor)(1000rpm to fuel cut)
-part load (small one inside the cage) (the one that makes the car behave more civilized)
-main (the big one, the one we should shim in order to raise fuel cut rpm)
-excess fuel spring (used while cranking, below 500rpm)
rpm is pump rpm
EDIT: cleared some things, there was a mistake
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Hey, I owe pretty much all of it to the various VW diesel forums and a LOT of reading!!
You can see why totally disabling the intermediate spring wouldn't really make the car un-driveable, but it really wouldn't help anything. Adjusting the accelerator lever stop a fraction of an inch makes up for anything that spring can do. But I've read a bunch of posts with people saying that they had problems controlling engine speed properly after doing the governor mod - things like RPMs hanging when they got off the power pedal. That really seems to be what the intermediate spring's "purpose" is. The main spring on the other hand has enough travel to more or less completely negate any throttle input you're giving the engine... The "best" way to get the RPM range you want would really be to find the spring tension that accomplishes that, but unless you've got a cutaway pump like in that video and can do a lot of testing it'd be pretty hard to figure out exactly what spring you need. Master pump rebuilders like Giles no doubt have the knowledge to just put the right parts in - I'd bet a 6-pack that a Giles Superpump doesn't have any shims on the main spring!
-Bryn
edit: w00t - this was post #100 for me!