MKIV-Will Injector balance net better MPG

KERMA

Vendor , w/Business number
Joined
Sep 23, 2001
Location
here
TDI
99 beetle and 04 jetta
actually they do not close between pilot and main injection, they open to pilot needle lift (iirc around .1mm of needle lift off the seat, ......
for the injector to close between injection periods there would need to be two lobes on the camplate so pressure would decrease before increasing again

This is 100% correct
 

[486]

Top Post Dawg
Joined
Mar 1, 2014
Location
MN
TDI
02 golf ALH
486, as an example, you realize that some common rails injectors can have up to 5 independent injector firings? They are piezo-electric timed in milliseconds, and very much separate.

Sure, we are firing the nozzles mechanically, but the 2-stage do operate very quickly. The first stage's intent is only to reduce the 'marble' noise and make the engine run more quietly. That amount of fuel is injected in an advanced position.
I don't know CR injectors too well, but I'd assume they've got a separate valve in there controlling fuel flow. Open and close that valve and the nozzle will do whatever it does just as fast as the valve will operate.

Whereas these are opened only by pressure from the injection pump, which does not let off pressure from pilot injection to main injection, in fact it is rapidly ramping up pressure as the transition is occurring.
The initial opening is from the inlet pressure acting on the portion of the needle's diameter that is outside the seat of the nozzle. The portion inside the nozzle's seat only has the pressure of compression on it, so negligible. Once the needle lifts a small amount then injection pump pressure builds in the portion of the nozzle right before the holes, acting on the full area of the injector needle driving it upwards with rapidly increasing force. This is why you see injectors closing at a much lower pressure than they open at.
 
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Franko6

Vendor , w/Business number
Joined
May 7, 2005
Location
Sw Missouri
TDI
Jetta, 99, Silver`
There are some who comment that if they told me the sky was blue, I'd have to go outside and check.

The comment, coming second hand from someone who doesn't always get their facts straight, is just another opinion, and not necessarily correct. For example, we recently read from a performance thread that,"..extrude honing destroys injector nozzles...", which we have seen people take the honing to an extreme and wreck them, but there is this information from a Bosch website...

When Bosch says they use 'hydraulic grinding', it's because they can't say Extrude Honing, as that is a registered copywrite name. Not only does honing improve flow, there are two methods; a clay compound pressed through the passages and an oil slurry, that can be pushed and pulled through the orifices. These methods reduce cavitation and increase flow by smoothing out the injector fuel bore. A Michigan company we know uses both methods to make some of the best Cummins race nozzles around.

When we say they must pop and stop, and I don't know who has actually seen the spray pattern operated with high-speed photography, under actual operating conditions. But I know that common rail injections are separate injections, as seen on our oscilloscope.
No matter, if we are testing nozzles and the nozzle's pop pressure are individually tested for NOP1 and NOP2. If the nozzle does not control fueling without leaking or spraying, that nozzle may perform well in emulation on some test equipment, but fail in actual operation. Much changes compared to spray patterning into ambient air pressure or the extreme pressure of a charged cylinder.

We usually see only the worst of the nozzles which have melted or cracked pistons, when we get an engine to overhaul that has blown up. When we check them, the offending cylinders always have an injector that are near runaway fueling. I can fix some of these injectors, but most of the time, even injectors with less than 1,000 miles, these are injectors that never should have been installed, as they are faulty.

I don't expect anyone to follow our protocol, but we now install injectors in a vehicle with an engine in excellent condition, a great injection pump and 500 psi compression across the board. We check idle balance, fuel economy and drive them for effect. This has all but eliminated claims that 'these injectors don't work right.'

Nevada_TDI,

As I just said, getting idle balance and FE readings are the proof the injectors are working correctly. However, this is based on injectors that are popping at pressures at least, close to normal 220/ 300 bar. If the pressures are low, the idle balance will be close, regardless of disparity of fueling. There is a bell curve of fueling that you can plot by running NOP2 through a range of pressures, usually becoming more stable above 280 bar and losing consistency above 330 bar. Our opinion for setting injectors 'hot' at pressures above optimal settings will strain the injection pump and the injector will become more erratic. One of the benefits of hydraulic honing is to reduce cavitation as fuel enters the injector hole, but extreme pressures will negate the honing benefit.

We do not subscribe to the 'one size fits all', from 100-200hp nozzles.

I might add, the 1019/955 nozzles that we popularized have little, if anything, to do with the sizing of the a nozzle sold by the same number. You can just about say that about any of the nozzles copied by others who use Bosch numbers to hawk them. Call them clones, copies or even fakes, they rarely act the same as the original.
 
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Nevada_TDI

Top Post Dawg
Joined
Aug 17, 2008
Location
Reno, sort of...
TDI
2001 Jetta TDI
Frank, here are my Group 13 readings:
0.09/0.14/-0.02/-0.28
How do these look? They were set at 220/300 just like you suggested.
Granted, my engine may not have been up to normal operating temperature as the numbers were moving around slightly.
 
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Turbodude1

Veteran Member
Joined
Aug 16, 2005
Location
Auburn Maine
TDI
1999.5 Golf 2dr. RCII, sprint 520s, shine susp
Ok, finally got a free minute to hook up vcds. IQ was 4 and injector balance was -0.15, -0.16, 0.05, 0.26. I believe these are in spec?

I did change a faulty N75 valve and the the car seems smoother. I have no idea if it will affect mileage.
 

eddieleephd

Top Post Dawg
Joined
May 27, 2012
Location
Battle Ground, Wa
TDI
2002 jetta Wagon
Who did the tune?

PP520s aren't too big with a stock pump and a VNT-17 on an ALH. Common setup. But it depends on the tune (and the tuner).

40 MPG isn't horrible, but it's not great. I just filled my wagon tonight (PP357s with an 11mm pump and stock turbo, RC3+) and got 46.8. And I typically drive 75-80 on the highway. I'm in MA so weather is pretty similar.

I'd look at how the car is set up. Make sure static timing is perfect, and that timing is advanced (65-70 in VCDS Basic Settings block 2). You may want to advance the timing a bit in VCDS as well, but ask your tuner about that. These little things all add up.

You should also run some logs and make sure your turbo is responding to boost requests correctly. And look at injector balance. If it's way off you may want to send them out, but if not I'd work on other things first. Also look at MAF function. Sometimes MAFs do a slow fade and affect performance in minor ways, but the car seems to drive fine.
IBW is absolutely correct.
IQ at 5-6 definitely isn't helping, however, static timing is one of the most important aspects of the setup and another thing to consider is the hammer mod.
If your start of injection is off then your efficiency is off.
My car likes it a touch under the center line, after timing set the IQ and see what happens.
Took me a while to dial in.

Sent from my Armor_2 using Tapatalk
 

Andyinchville1

Veteran Member
Joined
Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
Something is wrong...if it isnt driving style(and I suspect it isnt as you get better mileage on the other cars) then there is something awry with the car. As a for instance, MY 03 wagon only gets 40 MPG in regular driving. And thats with a 6 Speed(ouch!). However, between custom nozzles and pump, a 2265 turbo and a ton of internal engine modifications...added to that winter tires 16 inch (blizzaks)at about 40, summer tires 18 inch (pilot supersports)....you should get waaaaay better mileage. Now, with either of my setups, I can get 46 or so...but big turbos like fuel...so it isnt as easy. Your 17 with pp520 setup and 5 speed is good for 48-59 MPG as measured on my own cars with the same mods as you.Clearly you are looking for the problem, which is good, however, I would look at the engine itself to be sure nothing is awry...and switch tunes at least temporarily to see if that tune is just too much for your style.
HI,

I found it interesting that in one of the posts above the poster said his fuel mileage went up each time he got a bigger turbo (I often suspected a freer flowing turbo could help with volumetric efficiency and hence MPGs at steady cruise)

Just curious, but what is your recipe recipe for fuel mileage on the higher end of your 48 to 59 MPG scale ?

Thanks

Andrew
 

Andyinchville1

Veteran Member
Joined
Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
I don't think new bodies are at all necessary for a good fuel economy nozzle. Good nozzles are necessary. Still don't know what nozzles except they are Bosio.

We run a very good Bosch nozzle DSLA P150 520, that includes the intermediate element and the stop collar. That makes for a very easy and accurate nozzle setup. We regularly get those nozzles to exceed 50 mpg, but mostly, the average driver is in the high 40's. One customer who we built the engine with mileage as the purpose, regularly exceeds 60mpg. That is exceptional. I am happy driving 80 and getting 40.

In the last year alone, we have rebuilt many engines with cracked or melted pistons that were due to runaway nozzles that were either not set or set very poorly. Of the blown up engines we rebuilt, we did condemn a number of Bosio nozzles because of uncontrolled fueling. This may be attributable to lackadaisical calibration or simply no calibration. When we attempted to repair these sets of nozzles, we could not and condemned them. We have, will and do regularly condemn nozzles that will not balance out. This is not directed at any particular company, but we all know the Chinese nozzles JBMorrison, for example, that were Bosch knock-offs.

We have developed a method of checking the accuracy of a nozzle install. This method does not work unless the injectors are firing at proper pressure. It is the VCDS Engine Module/ block 13 idle balance. Numbers that stray +/- .5 mg/str. are excessive and should be corrected.

The 'smell test' or even the EGT test are very weak ways to determine injector balance.
For example, we had one person say their EGT's were slightly high, 1000 degrees, but the exhaust gasses mix in the manifold and one cylinder was wildly hot with a runaway injector that was running -1.4 mg/str. compared to the other injectors. That is into piston-melting territory.
HI,

I've heard good things about you and your injector work and on my next go around I may reach out to you for that.

I did not know that you build engines as well .... what is the recipe for the 60 MPG engine you mentioned? .... I'm sure good injectors / balance for starters is a given ....

Thanks

Andrew
 
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