Injection Quantity (IQ) – Nozzle Size - Quantity Adjuster (QA) relationship

mnorton

Member
Joined
Nov 28, 2011
Location
Lethbridge AB
TDI
2000 Jetta
After a great deal of reading about all three of these topics and their interdependencies, I still need some clarification on a few points.

1. Why is a lower IQ number actually increasing the amount of fuel? My understanding is that the mg/str measurement is milligrams of fuel for every one stroke of the pump. In my mind, fewer mg of fuel is exactly that – less fuel for the same stroke.

2. Can adjusting the QA via the hammer mod allow small injectors to act like big injectors and visa versa? In other words, hammer the pump to greatly increase fuel delivery to my stock .170 nozzles until it’s hazy vs. hammer the pump to greatly reduce fuel delivery to my new .216 nozzles to reduce the smoke until it’s hazy. Having read about the “Evry mod” can I assume that there is much more to come with stock injectors? Maybe the crux of what I’m getting at is part of the magic (from a fuel perspective) within a Stage 1 tune on a stock engine?

3. Follow up to question 2, it is my understanding that larger nozzles can deliver “X” amount of fuel more quickly (earlier) than smaller injectors (takes a longer period of time to deliver the same “X” amount of fuel). I believe this helps to reduce exhaust gas temperature (EGT’s) because the fuel is burned sooner at the end of the compression stroke/beginning of the power stroke vs. later on in the power stroke. Am I correct in my thinking?

4. Is the IQ range within the VCDS software always the same (2.2 to 9.0) regardless of the position of the QA? For example, I’m at 3.9 with my stock nozzles. I install .216 nozzles and my IQ drops to 1.8 Will the VCDS actually show 1.8 or will it show 2.2 and only allow a change to say 3.0 at which time I will need to do the hammer mod to allow for an increased IQ which translates into less fuel for my larger nozzles?

5. How does the IQ range effect the output at wide open throttle (WOT)? Are the two independent of each other (less fuel at idle doesn’t mean less fuel at WOT – WOT fuel deliver is adjusted somewhere else) or is it a linear relationship (more fuel at idle = more fuel at WOT)? Is the answer to this question the same for QA?

Forgive me if these questions seem “newbie-ish”. I appreciate any insight that the community can provide.

Thank you.
 

arne487

Veteran Member
Joined
Jan 16, 2008
Location
Fort Collins, CO
TDI
'03 Golf TDI, '10 TDI Cup Jetta
Forgive me if these questions seem “newbie-ish”. I appreciate any insight that the community can provide.
It's exceedingly rare that we see someone new with such well thought out questions in my opinion. I could answer with my best guesses, but I'll wait on the experts.
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
It's exceedingly rare that we see someone new with such well thought out questions in my opinion. I could answer with my best guesses, but I'll wait on the experts.
It's my opinion as well and I too await better answers than I can give.
 

dieseleux

Théoricien -TDIClub Contributor
Joined
Nov 14, 2006
Location
Pas assez loin pour vider ma tank!
TDI
Jetta TDI 02
To understand, IQ is number to regulate engine idle at 903rpm...
Bigger nozzle, more fuel per injection, ecu compensate by decrease IQ to stabilise idle at 903rpm.
IQ is a good relative indicator for injection, not a absolute value.




Dieseleux
 

Drivbiwire

Zehntes Jahr der Veteran
Joined
Oct 13, 1998
Location
Boise, Idaho
TDI
2013 Passat TDI, Newmar Ventana 8.3L ISC 3945, 2016 E250 BT, 2000 Jetta TDI
After a great deal of reading about all three of these topics and their interdependencies, I still need some clarification on a few points.
1. Why is a lower IQ number actually increasing the amount of fuel? My understanding is that the mg/str measurement is milligrams of fuel for every one stroke of the pump. In my mind, fewer mg of fuel is exactly that – less fuel for the same stroke.
IQ, This is a "Calculated" value predicated on "Assumtions" made by the ECU based on sensor input.

In the injection pump you have a control collar that is positioned by an electronic servo. This servo is regulated by increasing or decreasing the voltage to overcome the return mechanism. Based on the voltage, a position is derived, a major "assumption" is that if the collar is at position X based on a specific voltage, then X quantity of fuel is being delivered...BUT

We can re-position the control head, thus affecting the position of the collar and change the voltage required to maintain a specific load (fuel output). Therefore, the "IQ" being a "best Guess" by the ECU will change.

If the Control collar requires less range of motion the "IQ" value will be lower thus a "lower Quantity" of fuel is presumed to be injected per stroke of the plunger. If the collar requires a greater range of motion, the "IQ" will be higher.

The "Calculated" IQ value will also affect how the ECU calculates boost and other mapping values, so this will affect the engine output across the whole performance spectrum.

The range is 2.8 to 9.0, ideally if everything is working in good harmony an IQ value of 4.0-5.0 should net you no smoke output and best overall performance in respect to power and fuel economy.

A Lower IQ value shifts the performance in favor of power, and fuel economy will suffer, and visa versa.


2. Can adjusting the QA via the hammer mod allow small injectors to act like big injectors and visa versa? In other words, hammer the pump to greatly increase fuel delivery to my stock .170 nozzles until it’s hazy vs. hammer the pump to greatly reduce fuel delivery to my new .216 nozzles to reduce the smoke until it’s hazy. Having read about the “Evry mod” can I assume that there is much more to come with stock injectors? Maybe the crux of what I’m getting at is part of the magic (from a fuel perspective) within a Stage 1 tune on a stock engine?
This depends...

The injection pump produces a single pressure pulse, this single pressure pulse is broken up into two very distinct injection sequences. These sequences determine the "Injection Window". In a stock car, the injection window is predicated on a very low flow nozzle, installing a higher flow nozzle completely negates the original "injection Window" and increased smoke, excess heat, nozzle damage, poor fuel economy, poor performance and incorrect sequencing of the injectors will occur. No amount of adjusting the "IQ" can affect the actual injection window and how the injectors break up the single pressure pulse aside from having the nozzle properly and precisely calibrated.

Even if you "lower the IQ Value" this will not change the original settings of the injectors, this can only be done mechanically and again your limited by the actual flow characteristic of the OEM nozzles. Put another way, no matter how hard you push you can't force an elephant thru a hole made for a mouse...Same applies to the fuel flowing thru the stock nozzle.

Stock nozzles are designed to inject relatively slowly, this allows a slow complete mixing of the fuel and air to minimize emissions, however you sacrifice efficiency since the loss in efficiency drives down NOx formation due to lower peak cylinder pressures and peak combustion temperatures in the combustion bowl. Combined with EGR and the net affect is cooler combustion temperatures but also a resulting loss in overall engine efficiency.

3. Follow up to question 2, it is my understanding that larger nozzles can deliver “X” amount of fuel more quickly (earlier) than smaller injectors (takes a longer period of time to deliver the same “X” amount of fuel). I believe this helps to reduce exhaust gas temperature (EGT’s) because the fuel is burned sooner at the end of the compression stroke/beginning of the power stroke vs. later on in the power stroke. Am I correct in my thinking?
You are correct. With a larger nozzle you can deliver X quantity of fuel significantly faster. This allows more time for that fuel to burn. You now have options, you can either inject more fuel and increase output, OR inject less fuel and trade performance for fuel economy. With a lower quantity of fuel being injected in a shorter period of time (relative to crank rotation), thus you give the fuel more time to bond with the air and burn more completely. You also get a reduction in EGT since the crank is able to better convert that gas energy into real mechanical work. Since less energy is being wasted, the more complete combustion lowers the EGT (TIT - Turbine Inlet Temperature) despite a higher actual combustion bowl temperature due to higher peak cylinder pressure.

Keep in mind that anytime you inject fuel later in a combustion stroke, you have less time to take advantage of the gas energy being generated, earlier (to a point) is always better. And again this takes us back to how the injectors break up the single pressure pulse on an engine in respect to the precise metering and sequencing and commencement of the combustion event's (Pilot and Primary).

4. Is the IQ range within the VCDS software always the same (2.2 to 9.0) regardless of the position of the QA? For example, I’m at 3.9 with my stock nozzles. I install .216 nozzles and my IQ drops to 1.8 Will the VCDS actually show 1.8 or will it show 2.2 and only allow a change to say 3.0 at which time I will need to do the hammer mod to allow for an increased IQ which translates into less fuel for my larger nozzles?
It should read 2.8, less than 2.8 creates a conflict in the ECU software between the "Idle control" and "Load Control". Less than 2.8 and the engine has a hard time transitioning from Load control to Idle control when decelerating below 1500 rpm...this causes the proverbial "Idle Stumble" which is a direct result of this conflict in software.


5. How does the IQ range effect the output at wide open throttle (WOT)? Are the two independent of each other (less fuel at idle doesn’t mean less fuel at WOT – WOT fuel deliver is adjusted somewhere else) or is it a linear relationship (more fuel at idle = more fuel at WOT)? Is the answer to this question the same for QA?
I think I explained this in the earlier answer above, let me know if it's cleared up?

Forgive me if these questions seem “newbie-ish”. I appreciate any insight that the community can provide.
Thank you.
Great questions!
Happy New Year!
DBW
 
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whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
The fuel quantity is a closed loop, though. There is the N146 Quantity Adjuster which moves the QA collar, then there is the G149 which is the Modulating Piston Displacement Sensor that gives the feedback to the ECU. This just means that it's not a "calculated" value, but an "assumed" value. The "assumption" is that the ECU knows that a certain point of feedback equals a certain amount of fuel. But we can fool the ECU.

By moving the top (Hammer mod) you are moving the position of the feedback sensor, so that a given voltage to the QA gives a different feedback signal.

At least that has been my understanding.
 

Seatman

Top Post Dawg
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Apr 23, 2010
Location
Scotland
TDI
2014 Skoda rapid elegance 1.6 cr tdi
Holy cow dbw, I can feel my brain melting out my ears lol :D
 

ymz

Top Post Dawg
Joined
May 12, 2003
Location
Between Toronto & Montreal
TDI
2003 Jetta TDI Wagon, 2003 Jetta TDI Wagon
Aren't you glad you asked, Matt?

Feel free to drop in on your way back home... I have a large supply of Aspirins...

Happy New Year !!!

Yuri
 

KERMA

Vendor , w/Business number
Joined
Sep 23, 2001
Location
here
TDI
currently 99 beetle and 2011 335d
After a great deal of reading about all three of these topics and their interdependencies, I still need some clarification on a few points.
1. Why is a lower IQ number actually increasing the amount of fuel? My understanding is that the mg/str measurement is milligrams of fuel for every one stroke of the pump. In my mind, fewer mg of fuel is exactly that – less fuel for the same stroke.
Keep in mind, the ECU doesn't actually measure FUEL, it measures VOLTS at the fuel pump positioner. There is a map in the ecu that translates between volts and fuel. This map is calibrated for stock injectors.

There is no fuel meter measuring actual fuel flow, only feedback volts from the IP positioner. The ECU has to look at it's calibration map(s) to figure out how this voltage actually translates to the amount of fuel per injection event. The "IQ" number you see when you look at VCDS only relates to the feedback volts, and the ECU assigns an "IQ" number based on the value it finds in its calibration map.

To reiterate: The ecu IS NOT measuring fuel, it is measuring volts, and correlating that volts with a fuel number based on it's maps.

The idle control in the ECU sets a target engine speed. The ECU will then adjust the pump volts according to its closed loop feedback signal as needed to maintain that target idle speed. IOW, it will change VOLTS up or down to achieve the target engine speed.

If it needs less volts to maintain engine speed, the ECU reports less mg/r when you look at diagnostics using VCDS. If it needs more volts to maintain engine speed, the ECU reports more mg/r. When you "hammer mod" you are only changing the CALIBRATION or correlation between volts and fuel mg, and the ecu simply reports what it sees according to the calibration it finds on its maps. The actual physical amount of fuel doesn't change, because it takes a fixed amount of fuel to maintain a fixed idle speed, generally speaking.

SO, why does lower IQ (displayed number) at idle mean more full load power ("more fuel")? Because when calculating off-idle volts, the ECU doesn’t subtract the idle volts. It simply "goes" to whatever the IQ limit is. If 6 mg are already "taken up" by the idle, there's less collar travel available, and therefore less power than if the idle only "takes up" 2 mg.

For (another hypothetical) example, a good full-load number for a stock ALH might be 38 mg/r. On the pump volts map, this may correspond to 3.5 volts at full load. Idle volts may indicate 1.2 volts at idle, corresponding to 6 mg/r. Therefore, the ECU has a dynamic range of 32 mg, or 2.3 volts to work with, which is the IQ difference between idle and full load. It can move the positioner over a 2.3 volt range before it reaches the programmed torque limit of 38 mg/r

Now let's physically move the positioner ("hammer" mod) to "recalibrate" so that the positioner only needs 1.0 volts to maintain idle. ECU may report that lower voltage as corresponding to 2.0 mg at idle according to its map. However: NOW the ECU has a dynamic range of 36 mg, or 2.5 volts ! The positioner can move farther before reaching the programmed torque limit = more fuel delivery = more power!

To sum up our hypothetical example:

Limit fuel quantity = 38 mg = 3.5v on map

1.2v @ 6mg -> 32 mg @ limit = 2.3 volts
1.0v @ 2mg -> 36 mg @ limit = 2.5 volts

Hope this helps.

2. Can adjusting the QA via the hammer mod allow small injectors to act like big injectors and visa versa? In other words, hammer the pump to greatly increase fuel delivery to my stock .170 nozzles until it’s hazy vs. hammer the pump to greatly reduce fuel delivery to my new .216 nozzles to reduce the smoke until it’s hazy. Having read about the “Evry mod” can I assume that there is much more to come with stock injectors? Maybe the crux of what I’m getting at is part of the magic (from a fuel perspective) within a Stage 1 tune on a stock engine?
Not really. When you adjust the idle IQ, you are only changing the OFFSET of ONE MAP (pump volts) and changing the available range of positioner movement. The delivery rate at the limit will change slightly with idle IQ as discussed above, but the intermediate values and their relation, slope, etc won’t change. However, the positioner is on a feedback loop with the accelerator pedal , so the driver still gets exactly as much fuel as he wants within the available range, right up to the limit.

3. Follow up to question 2, it is my understanding that larger nozzles can deliver “X” amount of fuel more quickly (earlier) than smaller injectors (takes a longer period of time to deliver the same “X” amount of fuel). I believe this helps to reduce exhaust gas temperature (EGT’s) because the fuel is burned sooner at the end of the compression stroke/beginning of the power stroke vs. later on in the power stroke. Am I correct in my thinking?
This would be true, if the peak cylinder pressure occurs at the same crank angle as before (which it doesn't)

Lots of other engine parameters get their cue from the requested or actual IQ number, and different injectors throw everything else "off". It’s a lot of work and difficult to realign all these "other" parameters to bring everything back in calibration. Properly adapting bigger injectors is more difficult than a simple QA realignment



4. Is the IQ range within the VCDS software always the same (2.2 to 9.0) regardless of the position of the QA? For example, I’m at 3.9 with my stock nozzles. I install .216 nozzles and my IQ drops to 1.8 Will the VCDS actually show 1.8 or will it show 2.2 and only allow a change to say 3.0 at which time I will need to do the hammer mod to allow for an increased IQ which translates into less fuel for my larger nozzles?
Remember, the ECU is not measuring physical fuel, it is measuring VOLTS at the positioner feedback. When you change injectors, the calibration is "off" so the adjustment range is also affected.


5. How does the IQ range effect the output at wide open throttle (WOT)? Are the two independent of each other (less fuel at idle doesn’t mean less fuel at WOT – WOT fuel deliver is adjusted somewhere else) or is it a linear relationship (more fuel at idle = more fuel at WOT)? Is the answer to this question the same for QA?

Forgive me if these questions seem “newbie-ish”. I appreciate any insight that the community can provide.

Thank you.
You're welcome.

I believe this was answered already. Higher idle IQ means more fuel is "taken up" by idle, lower idle IQ means less fuel is "taken up" by idle, leaving more adjustment range for full power.
 
Last edited:

mnorton

Member
Joined
Nov 28, 2011
Location
Lethbridge AB
TDI
2000 Jetta
Happy New Year everyone!

After reading and re-reading the various responses I now have some answers and additional thoughts. See my responses in GREEN

1. Why is a lower IQ number actually increasing the amount of fuel? My understanding is that the mg/str measurement is milligrams of fuel for every one stroke of the pump. In my mind, fewer mg of fuel is exactly that – less fuel for the same stroke.

The notion of IQ as a measurement of voltage and not actually the metering of fuel is a critical point for this question.

Drivbiwire:
We can re-position the control head, thus affecting the position of the collar and change the voltage required to maintain a specific load (fuel output). Therefore, the "IQ" being a "best Guess" by the ECU will change.

If the Control collar requires less range of motion the "IQ" value will be lower thus a "lower Quantity" of fuel is presumed to be injected per stroke of the plunger. If the collar requires a greater range of motion, the "IQ" will be higher.

KERMA:
The idle control in the ECU sets a target engine speed. The ECU will then adjust the pump volts according to its closed loop feedback signal as needed to maintain that target idle speed. IOW, it will change VOLTS up or down to achieve the target engine speed.

If it needs less volts to maintain engine speed, the ECU reports less mg/r when you look at diagnostics using VCDS. If it needs more volts to maintain engine speed, the ECU reports more mg/r. When you "hammer mod" you are only changing the CALIBRATION or correlation between volts and fuel mg, and the ecu simply reports what it sees according to the calibration it finds on its maps. The actual physical amount of fuel doesn't change, because it takes a fixed amount of fuel to maintain a fixed idle speed, generally speaking.

These statements have helped me greatly in understanding that the engine only ever needs a certain amount of fuel to idle and how the ECU controls that is by a voltage reading (at the pump servo) that can be changed. It can be changed via the VCDS software, the hammer mod or by installing different nozzles.

So when I go back to my original question, I’m no longer thinking about the mg/s as a metered measurement of fuel but rather the amount of volts necessary to provide a certain amount of fuel to idle at a fixed rate i.e. 903/rpm.

I would also like to point out this important statement by KERMA.


SO, why does lower IQ (displayed number) at idle mean more full load power ("more fuel")? Because when calculating off-idle volts, the ECU doesn’t subtract the idle volts. It simply "goes" to whatever the IQ limit is. If 6 mg are already "taken up" by the idle, there's less collar travel available, and therefore less power than if the idle only "takes up" 2 mg.

For (another hypothetical) example, a good full-load number for a stock ALH might be 38 mg/r. On the pump volts map, this may correspond to 3.5 volts at full load. Idle volts may indicate 1.2 volts at idle, corresponding to 6 mg/r. Therefore, the ECU has a dynamic range of 32 mg, or 2.3 volts to work with, which is the IQ difference between idle and full load. It can move the positioner over a 2.3 volt range before it reaches the programmed torque limit of 38 mg/r

Now let's physically move the positioner ("hammer" mod) to "recalibrate" so that the positioner only needs 1.0 volts to maintain idle. ECU may report that lower voltage as corresponding to 2.0 mg at idle according to its map. However: NOW the ECU has a dynamic range of 36 mg, or 2.5 volts ! The positioner can move farther before reaching the programmed torque limit = more fuel delivery = more power!

I understand this to mean that you really want the lowest IQ number you can manage (with reasonable/appropriate idle qualities) to have the greatest possible power throughout the entire RPM range.

2. Can adjusting the QA via the hammer mod allow small injectors to act like big injectors and visa versa? In other words, hammer the pump to greatly increase fuel delivery to my stock .170 nozzles until it’s hazy vs. hammer the pump to greatly reduce fuel delivery to my new .216 nozzles to reduce the smoke until it’s hazy. Having read about the “Evry mod” can I assume that there is much more to come with stock injectors? Maybe the crux of what I’m getting at is part of the magic within a Stage 1 tune on a stock engine?

As stated by both Drivebiwire and KERMA, this really isn’t the case however the notion of the “injection window” which I presume is dictated by the ECU map and physical setup of the injectors (shims and springs) in my mind are essential pieces to the puzzle.

I suppose in an ideal world, every nozzle change should have a corresponding map change. I’ve read that the only difference between the 110 HP 1.9 TDI and the 90 HP TDI was the larger nozzles (.205 vs. .170) however I suspect that the 110 HP map is different as well.

Question - how does Injector Pump (IP) timing affect everything stated above? Can you have the “injection window” occur sooner by advancing the pump? Is this advantageous when installing larger nozzles?


3. Follow up to question 2, it is my understanding that larger nozzles can deliver “X” amount of fuel more quickly (earlier) than smaller injectors (takes a longer period of time to deliver the same “X” amount of fuel). I believe this helps to reduce exhaust gas temperature (EGT’s) because the fuel is burned sooner at the end of the compression stroke/beginning of the power stroke vs. later on in the power stroke. Am I correct in my thinking?

Drivebiwire’s answer is what I expected to see however I must admit that I’m confused by KERMA’s response:

This would be true, if the peak cylinder pressure occurs at the same crank angle as before (which it doesn't)

Question - maybe I’m over simplifying the issues but isn’t peek cylinder pressure always the greatest at the top of the compression stroke? Maybe KERMA’s statement is more about the criteria for engine load (boost, fuel, advance, etc.) than the basic operations of the four strokes.

4. Is the IQ range within the VCDS software always the same (2.2 to 9.0) regardless of the position of the QA? For example, I’m at 3.9 with my stock nozzles. I install .216 nozzles and my IQ drops to 1.8 Will the VCDS actually show 1.8 or will it show 2.2 and only allow a change to say 3.0 at which time I will need to do the hammer mod to allow for an increased IQ which translates into less fuel for my larger nozzles?

This has been answered by both Drivebiwire and KERMA – thank you.

5. How does the IQ range effect the output at wide open throttle (WOT)? Are the two independent of each other (less fuel at idle doesn’t mean less fuel at WOT – WOT fuel deliver is adjusted somewhere else) or is it a linear relationship (more fuel at idle = more fuel at WOT)? Is the answer to this question the same for QA?

This has been answered by both Drivebiwire and KERMA – thank you.

I greatly appreciate the sharing of the collective expertise of the forum. I hope with time I'm able to be the one giving the answers :)

Matt
 
Last edited:

Airstream

Veteran Member
Joined
Aug 17, 2011
Location
Asheville, NC
TDI
2000 Jetta; 2010 JSW
BUMP for excellent information in this thread.

I just got VCDS and have been testing these values. My stock vehicle's original IQ when I checked it was about 1.6 Given that point, I have never seen even a haze of dark smoke from my car, even when friends followed me at night. (However my timing was on the red retarded line up until a few days ago)

The lowest value in VCDS for IQ (36645) got me to 3.6/3.8 at idle and I noticed a definite drop in power. Today I went in and played at a few settings. I noticed however that as I lowered the IQ (i.e. lowered economy and raised power) the fuel consumption VCDS reported at idle kept dropping. So at an IQ of 3.8, VCDS showed idle fuel consumption to be .5 l/h and it consistently dropped at the IQ was lowered until at an IQ of 2.0 fuel consumption was .2 l/h.

I was greatly confused, but if I read this thread correctly it makes more sense now...at least I will take a stab:

Since a
Higher idle IQ means more fuel is "taken up" by idle, lower idle IQ means less fuel is "taken up" by idle, leaving more adjustment range for full power
then with a higher IQ the computer is reading that it is taking more fuel to keep the engine at idle thus it reduces the range of fueling allowed through the rest of the range with the effect of decreasing power and increasing economy.

With a lower IQ at idle, the computer (volts) reads less of the fuel range is required to keep the car at idle so there is a larger range of fuel allowed; thus more power and potentially less economy.

So my assumption is that even if the computer reads a higher fuel consumption at idle with a a high IQ it won't hold true throughout the range. (but is it true at the idle? Or is the pump just reading more volts at a higher IQ?)


All this is extremely helpful information, but I am still a little dim about where to set my IQ. the stock setting it is about 1.6; Pete says it shouldn't be any lower than 2.8, and at 3.8 the car was a pretty sluggish at the lower end. SO maybe I will set it at 3.0 and forget it....until I replace my old 200k mile nozzles...

Thanks all for the valuable information I may have completely mis-interpreted!
 

03Springer

Veteran Member
Joined
Mar 4, 2003
Location
Southern Nevada
TDI
2003 Golf GL+ 2013 A3 TDI
If you have your static timing in the upper portion of the graph then go perform the hammer mod. Prior to this make sure the IQ is set at 32768 then loosen the the four fasteners on the pump, tap with a mallet until the IQ is at approximatley 3.0, the engine can be running while you are doing this. Just remeber that when you tighten the four fasteners the IQ will change slightly.
 

Airstream

Veteran Member
Joined
Aug 17, 2011
Location
Asheville, NC
TDI
2000 Jetta; 2010 JSW
I understand that will change the possible range of the IQ but 3.0 is 3.0 whether I do the hammer mod or not correct?

I will definately need to do the hammer mod when I get bigger nozzles, but I don't see the need for it right now. 3.8 felt pretty weak to me given my stock nozzles.

Or am i missing something?
 

03Springer

Veteran Member
Joined
Mar 4, 2003
Location
Southern Nevada
TDI
2003 Golf GL+ 2013 A3 TDI
This is from Ross-Tech

Channel 1: injected quantity
  • Check the injected quantity at idle, engine warm and all power consuming devices turned off.
  • Specification is 2.5 to 9 mg/h.
  • To change the amount of injected fuel perceived by the ECU, go to adaptation channel 1.
  • If you have driveability problems, you may want to increase it to 3-4 mg/h.
  • For slightly improved throttle response, you may try to decrease the value.
I think if you hammer mod and get it set for approximately 3.0 then if you require a little more or less then you will be right in the middle of the adjustment area (electronically) as stated above. Make sense?
 

Evgeniy K.

Veteran Member
Joined
Apr 16, 2009
Location
Ukraine, Zaporozhye
TDI
1.9 TDi AHF AT 3DR 2000.
Ok.
Changing IQ number doesnt change real fuel at iddle.
The question:
But - Why if i change IQ from 4 to 7 the iddle change its sound to better?
I read here "if less then 2.8 = problem+shake iddle". Yes - if i make 2.5 - my engine shakes.

If hammer mod only change voltage response to ECU, we have:
1. Real Volts are 1.0v=5mg by voltage map. IQ=5. We ask for 3.2v, we have some travel in plunger, and it give us 53mg fuel.

2. And now we moved sensor from driver's side (hammer mod) = feedback now is 0.8v = 4mg. If we ask 3.2v feedback, the real travel of plunger will be more = 55mg fuel.
If we move sensor to driver's side - feedback will be 1.2v= 7mg. We ask for feedback 3.2V, plunger makes less travel than before, and we get only 50mg fuel.

Its clear and good.

The question:
Now we set 0.260 nozzle.
I dont remember, what was happend with my car with IQ value, but as i read here:
IQ from our stock 5 goes to IQ 2.7. ECU needs now only 0.7v plunger travel, search in voltage map proper IQ for 0.7V and show us IQ 2.7 (with 0.205 nozzle ECU need 1v travel= IQ 5mg).

As i remember, I had iddle shake untill i hammer mode it to IQ=5. So i trick ECU, and feedback now again 1v= IQ 5mg.

I dont remember exactly, what was happened, but trying to understand, why my Engine shakes when i make IQ=3 or lower with Bigger nozzles? ECU dont like output signal less than 1v?
 
Last edited:

Evgeniy K.

Veteran Member
Joined
Apr 16, 2009
Location
Ukraine, Zaporozhye
TDI
1.9 TDi AHF AT 3DR 2000.
Also can't understand, why stock or tuned car have better engine sound and smell with Higer IQ.
If real IQ don't changing, why if we trick ECU by hammer mode to show us bigger IQ - the engine sounds better? but if we hammer it to lower IQ it sounds bad and even shake at light load?

About Voltage Map calibration:
If i set big nozzles, Vag give 2.8 IQ, i have engine shake. You want "4"? OK! - I recal the Pump voltage map, saying that 5 mg now requires "1150", not "1290" - Vag com shows my my 4mg IQ again without any hammer mode. It seems to be allright. But not! - Engine has some shake at iddle or light load.
I hammer it for IQ 7 = all right now, but "7" is too high for the eye, because the car used the same 4mg in real. So i recalibrate low mg values to stock, and IQ change itself from 7 to 4. No shake.

Because of it, no matter that ECU show us IQ "4" if i recal the map for it, but voltare response does matter. It seems - ECU bon't like low volt signals?
Why it shake untill you hammer it to fool feedback signal?

So, without hammer mode I have Engine shake, untill i fool the ECU by rising output signal.
 
Last edited:

cidades

Veteran Member
Joined
Feb 17, 2010
Location
Portugal
TDI
Golf MK4 >> AHF(81kW)
I think the engine sound is different when IQ change due to SOI map.



Someone confirm that with vag-com, changing the IQ and then see if start of injection at idles changes.
 

mk3

Veteran Member
Joined
Sep 13, 2005
Location
Wisconsin, USA
TDI
03 Jetta GLS 5-speed
Great thread!

One thing that I don't think has been mentioned is the fact that the relationship between fuel flow and quantity adjuster position will be affected by temperature. This is why there is a very reliable and precise fuel temperature sensor built into the pump. I guess there must be some MAP and or calculations for temperature in the ECU. Temperature probably also affects timing so don't get any ideas about hacking the temp sensor!

I started a thread a few weeks back sort of related. I was trying to reverse-engineer the QA/ voltage / actual fuel / temperature / hammer mod relationship.


http://forums.tdiclub.com/showthread.php?t=350996

I need to redo some of it since I found I had an insanely plugged intake manifold just in case that fact skewed something.

I think the biggest problem with the IQ changes and hammer mod is that the adjustment is a simple offset - you/we are forcing the engine computer to have the wrong value for fuel at idle so that under load the relationships are more correct. I think this causes some problems with driveability (it stalls easier). It would be a little bit more correct to have a scale factor for the QA so one could keep the idle IQ reading the same and have the voltage/quantity relationship altered for different nozzles and/or pumps.
 

branger

Veteran Member
Joined
Jan 30, 2010
Location
Maple creek,sk, canada
TDI
2001 jetta alh tdi 1.9L (recently sold),2013 A6 jetta tdi 2 litre DSG
after reading this thread it got me thinking now about my current set up , i adjusted hammer mod down to 1.6 to achieve more power as it was around 5 before and was kind of gutless. This has greatly helped that end of the spectrum , no blue smoke yet at the setting so wasn't worried. Here is my question now tho after my newfound knowledge, Since the lower iq setting is less fuel at idle that would mean less fuel available for start up purposes? been having hard starts since adjustment am i correct in this thinking or has nothing to do with it?
 

robnitro

Veteran Member
Joined
Jan 19, 2004
Location
NYC area, NY
TDI
2001 Jetta TDI GLS silver
No, IQ number at idle doesn't mean actual fuel, just the "starting point" of the IQ range.
Idle is same fueling, without change in rpm or hardware. Whatever real number it may be, it is unrelated to this IQ number. Idle is purely set by how fast the engine is turning and the load on the engine at idle.

Hammer mod changes the voltage needed for a certain IQ. The range is 0-5v (but 5v is too much and causes errors). Your tune's pump voltage map sets this max.

So if you hammer the IQ down, you are actually changing the voltage needed for the same fuel, by mechanically changing the range that the QA adjuster uses to set up fueling quantity.

Example: original was IQ 4, with 1.56v. Top IQ lets say is 45 at 3.6v

example: hammered to 1.6, it says 1.36v, so now you have 0.2 more volts to play with on the pump map. Now top IQ of 45 is still 3.6v, but with the pump needing less volts to do the same real fuel (hammer mod), so really it only needs around 3.4v (-0.2v hammer mod) for that IQ 45.
So basically, you are virtually pushing 3.8v for that same IQ 45, meaning more fueling.

Too much hammer mod can cause the engine to run rough at idle (baby cummins sound, lol), why?
It is because if you adjust it too low, the mechanical adjustment is set where even zero volts is pushing fuel, so you lose the fine range ability for the pump to trim down fueling down low.
 
Last edited:

branger

Veteran Member
Joined
Jan 30, 2010
Location
Maple creek,sk, canada
TDI
2001 jetta alh tdi 1.9L (recently sold),2013 A6 jetta tdi 2 litre DSG
ok that makes perfect sense thanks for clearing any confusion up that i had all is well and right where i want it then
 

Houpty GT

Veteran Member
Joined
Aug 31, 2008
Location
South Carolina
TDI
Corrado TDI, 2000 Golf, 1996 B4 Variant
I just noticed this thread. I figured this out on my own in the last week or so but what I have not figured out is what changing the IQ in adaptation is doing. Does adaptation make changes to the fuel maps or is it more of a top end fuel cutoff? This would make it something different entirely from what the hammer mod does. Which is interesting because people often recommend one or the other.

So what is IQ adaptation actually doing?
 

robnitro

Veteran Member
Joined
Jan 19, 2004
Location
NYC area, NY
TDI
2001 Jetta TDI GLS silver
IQ adaptation changes the number IQ that is displayed for a voltage, at idle.

Let's say your pump voltage map specifies 1.56v for IQ 4, like in the last example.
Let's say your max IQ is 45, at 3.6v, like in the last example.
The difference in voltage between min and max

If you adapt IQ lower, you have same 1.56v, but IQ says 2. It shifts the IQ number instead of the voltage because originally on pump voltage map, 1.56v is IQ 4.

So, the original difference in voltage was 3.6-1.56v= 2.16v for the range. Now because you lowered the IQ in adaptation, there is 2 more IQ in the range (45-4=41, 45-2=43). So it will actually be fueling 47 IQ instead of 45 at the max, and everything else in between is shifted over by 2 IQ. Essentially it is asking for more voltage to get that, because when it moves over 43 IQ units, it asks the pump voltage map for 47 instead of 45. So where the map said 3.6v for 45, now its looking up a higher value on pump voltage, like lets say 3.8v.

So basically it is changing the way the ECU looks up the pump voltage map. Stock was looking at 45 column value for 45. Adapted down by 2 IQ it is looking at the map +2: example: 10->12, 20->22 , 45->47 ,etc
 
Last edited:

Mastef76

Member
Joined
Apr 13, 2012
Location
italy
TDI
A3 8L 1.9tdi AGR anno 2000
A> Audi A3 1997 >> AHF ALH> Unità di alimentazione> Autodiagnosi>
Autodiagnosi

Di lettura valori specificati per la pompa di iniezione

Mostra gruppo 01 il motore al minimo (motore caldo, la temperatura del liquido di raffreddamento non inferiore a +85 ° C)

Leggi blocco misurato valore 1 ⇒ ◂ indicato sul display
900 giri 5,6 mg / corsa 1,480 V 87,3 ° C
Temperatura del liquido di raffreddamento
▪ 85 ... 100 ° C ok
▪ <85 ° C: => Far girare il motore fino a caldo
Tensione di movimento del pistone modulante mittente-G149
▪ 1,250 ... 1,700 V ok
▪ <1,250 V: pompa di iniezione troppo ricca => sostituire
▪> 1,700 V: motore di carico => consumatori switch off, pompa di iniezione troppo magra => rinnovare la pompa di iniezione
Iniezione quantità
▪ 2,0 ... 6,0 mg / corsa OK
▪ <2,0 mg / corsa: pompa di iniezione troppo ricca => sostituire
▪> 6,0 mg / corsa: motore di carico => consumatori switch off, pompa di iniezione troppo magra => sostituire la pompa di iniezione
Regime del motore
▪ 860 ... 940 rpm OK
Mostra gruppo 01 con inizio tentato (se il motore non si avvia) 1)

Leggi blocco misurato valore 1 ⇒ ◂ indicato sul display
230 rpm 37,4 mg / corsa 2,780 V 14,3 ° C
Temperatura liquido di raffreddamento
Tensione dal movimento del pistone modulante mittente-G149 (regolatore quantità restituisce la posizione del pistone modulante all'unità di controllo)
▪ aumenti periodici di tensione: va bene (pompa iniezione)
▪ <1.000 V: controllo di misurazione chiuso => osservare visualizzazione zona 2, solo se specificato la quantità di iniezione ok => sostituire la pompa di iniezione
Quantità di iniezione specificato (unità di controllo di attivare il controllo di dosaggio in pompa di iniezione)
▪ periodici aumenti di quantità di iniezione: va bene (pompa è in corso di attivazione)
▪ 0,0 mg / Errore di sistema corsa => interrogare la memoria guasti, pagina 01-6
Regime del motore
1) Se la tensione del sistema elettrico scende al di sotto di 10,8 V durante l'avvio tentativo, il VAG 1551 lettore guasto verrà interrotta la diagnosi.

Mostra gruppo 19 con accensione

Leggi blocco misurato valore 19 ⇒ ◂ indicato sul display
0,780 V 4,150 V
Nessuna indicazione
Nessuna indicazione
Tensione al sensore per il movimento del pistone modulante con controllo di dosaggio alla fermata massima
▪ 3,800 ... 4,400 V ok
▪ Se fuori tolleranza: Controllare la resistenza di contatto nel cablaggio => Pagina 23-92
▪ pompa di iniezione di regolazione quantità disadattati => sostituire la pompa di iniezione
Tensione al sensore per il movimento del pistone modulante con controllo di dosaggio alla fermata minimo
▪ 0,600 ... 0,900 V ok
▪ Se fuori tolleranza: Controllare la resistenza di contatto elettrico => Pagina 23-92
▪ pompa di iniezione di regolazione quantità disadattati => sostituire la pompa di iniezione
Visualizza Gruppo 04 il motore al minimo (motore caldo, la temperatura del liquido di raffreddamento non inferiore a +85 ° C)

Leggi blocco misurato valore 4 ⇒ ◂ indicato sul display
900 giri 0.9 ° prima del PMS 0.9 ° prima del PMS 3%
Ciclo di lavoro (attivazione) della valvola di iniezione di inizio
▪ alcuna specifica
Iniezione Inizio corrente
▪ 2 ° dopo il PMS ... 4 ° prima del PMS bene.
▪ In seguito 2 ° dopo il PMS: temporizzazione di controllo iniezione bloccato
▪ Inizio della valvola di iniezione difettosa
▪ pompa di iniezione eccessivamente ritardata
▪ => Verifica tempi di iniezione gamma di controllo, pagina 23 -59
Iniezione iniziare specificato da unità di controllo
▪ 2 ° dopo il PMS ... 4 ° prima del PMS OK
Regime del motore
▪ 860 ... 940 rpm OK
Visualizza Gruppo 04 a tutto gas (test drive in 3a o in 4a, la temperatura del liquido di raffreddamento non inferiore a +85 ° C)

Leggi blocco misurato valore 4 ⇒ ◂ indicato sul display
4060 rpm 16.3 ° prima del PMS 16.1 ° prima del PMS 84%
Ciclo di lavoro (attivazione) della valvola di iniezione di inizio
▪ Nessuna specifica
Iniezione Inizio corrente
▪ Se, come specificato nel gruppo di visualizzazione 2 (tolleranza di ± 2 °) va bene.
▪ Se fuori tolleranza: pompa di mandata iniezione iniziare errato
▪ => controllare inizio dell'iniezione,
▪ Pagina 23-59
Iniezione iniziare specificato da centralina
▪ 14 ... 18 ° prima del PMS bene.
Regime del motore
▪ 3800 ... 4200 rpm OK
 

robnitro

Veteran Member
Joined
Jan 19, 2004
Location
NYC area, NY
TDI
2001 Jetta TDI GLS silver
I know its an old post, but I realized that I have an explanation for the shake.

The ecu n146 map doesn't differentiate much below around 0.9v, so if you hammer to use less than that, the engine shakes because it only knows 0 or 0.9, no smooth control to keep idle, you get up and down.

Also can't understand, why stock or tuned car have better engine sound and smell with Higer IQ.
If real IQ don't changing, why if we trick ECU by hammer mode to show us bigger IQ - the engine sounds better? but if we hammer it to lower IQ it sounds bad and even shake at light load?

About Voltage Map calibration:
If i set big nozzles, Vag give 2.8 IQ, i have engine shake. You want "4"? OK! - I recal the Pump voltage map, saying that 5 mg now requires "1150", not "1290" - Vag com shows my my 4mg IQ again without any hammer mode. It seems to be allright. But not! - Engine has some shake at iddle or light load.
I hammer it for IQ 7 = all right now, but "7" is too high for the eye, because the car used the same 4mg in real. So i recalibrate low mg values to stock, and IQ change itself from 7 to 4. No shake.

Because of it, no matter that ECU show us IQ "4" if i recal the map for it, but voltare response does matter. It seems - ECU bon't like low volt signals?
Why it shake untill you hammer it to fool feedback signal?

So, without hammer mode I have Engine shake, untill i fool the ECU by rising output signal.
 

Mastef76

Member
Joined
Apr 13, 2012
Location
italy
TDI
A3 8L 1.9tdi AGR anno 2000
Elsawin consiglia 5,6 mg
Voi quale valore --mg preciso mi consigliate di tarare con il martello?
 
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