IQ, QA voltage, duration, and timing question

[robnitro]

I've been reading older threads regarding IQ, QA voltage, and duration and have some questions.

I put in an 11mm pump and have IQ at 3.8 with seeing max QA 4.44v, 19.5 BTDC at higher rpm. It runs a haze with 23 psi and .216 (sprint 502) nozzles.

I've seen in some older threads that its best to keep QA at 4.2 v max (around IQ 5 or 6 for my setup), to keep the injection window closer to stock. What would be optimal advance for that kind of window? I can adapt it down to 17 degrees.

I'm also confused regarding QA voltage and fuel flow. Let's say at 4.2 v IQ is 5, if I put in bigger injectors, would that automatically drop the IQ but keep the QA at 4.2v?

Thanks in advance!

 

[dieseleux]

The best way to ajust fuel is use O2 wide band sensor.
If you see black smoke with lean reading, you have some trouble with timming and/or injection window.
At high power, most time you get some light haze with bosch VE pump, PD engine are better on this because PD injection are better atomisation.




Dieseleux

 

[robnitro]

So does that mean that QA voltage has nothing to do with determining a good injection window?

edit;
Just did some testing. I've been hitting quantity adjuster error (going above 4.5v) since 11mm pump install. IQ was 3.6, w QA at 1.7 v.
If I adapt group 1 to 32718, no problem. So I tried to hammer to that same IQ (4) without adaptation, QA was 1.76v. Exceeded the quantity adjuster limit at 32768 setting. went to 32718 (IQ 5) and no QA fault code.

So, the hammer mod seems to not help to prevent "warp field collapse", while IQ adaptation allows to reduce max QA voltage to prevent exceeding 4.5 v.

QA voltage seems to have no link unless one considers the idle voltage. Is the difference between idle V and max V the real measure of duration???

 

[ArturCosta]

If you are getting the error its because the remap is asking fuel the pump can not deliver.
My car is running 4.64v with 18,5º SOI at 4000rpm with 230bars injectors and there is nearly no smoke at 1.65bars.

I also have made a second remap with 1.1bars stock SOI and 3,9v and car runs 100% clean and makes more power then a PD130

 

[robnitro]

I don't understand about the fueling issue, because I never got the code with the 10mm pump, which can push less and was weaker at same IQ. In logs @ 32718, QA maxes out at 4.44v. Without adaptation, it would cut out at 4500 rpm but the logs were not able to show the voltage in time due to slow sample rate. Timing is perfect with N108 never too high.

What do you have your IQ at idle and what QA voltage at idle?

 

[ArturCosta]

I don't understand about the fueling issue, because I never got the code with the 10mm pump, which can push less and was weaker at same IQ. In logs @ 32718, QA maxes out at 4.44v. Without adaptation, it would cut out at 4500 rpm but the logs were not able to show the voltage in time due to slow sample rate. Timing is perfect with N108 never too high.

What do you have your IQ at idle and what QA voltage at idle?

IQ at idle with stock remap is 5mg (cant remember voltage)... with proper remap is 3mg.(I also tune the remap to get 3mg at hot idle)

I also had that problem with some cars with bigger pumps and I had to ask less fuel in the remap they where not able to make the same voltage as a hammered 10mm pump. My pump without hammer mod I think maxed out at 4.4v too.

 

[robnitro]

Odd how the 11mm pump acts differently for us. I suppose I will leave it as it is instead of going for a remap, because then I'd have to mail ecu in and wait- which is difficult because I need the car for work.

I'm just really curious why the hammer mod alone doesn't prevent exceeding QA when the IQ is bumped up (less fueling). If I am running well now with 32718 (instead of 32768), I should be fine, right?

 

[Rub87]

The best way to ajust fuel is use O2 wide band sensor.
If you see black smoke with lean reading, you have some trouble with timming and/or injection window.
At high power, most time you get some light haze with bosch VE pump, PD engine are better on this because PD injection are better atomisation.




Dieseleux

True, PD with r783 can run as low as 15.5 afr and still very very little smoke.. with VE I get to see some smoke under afr 17

 

[bhodgkiss]

Digging up an old thread....

My pump seems to max out at 4.44v (VCDS voltage) with some new maps I am trying. This is the highest value in the 51mg column (3.65v but there is the 1.21x factor between the two). I am asking for 56mg which should be about 4.84v at 4000rpm. There is a 60mg column which I've modified the numbers in as they were the same as 51mg)

So why isn't the pump delivering 56mg please?
I think I've got rid of all limiters for 51mg.
Can the pump just not go any higher please without some 'modification'?

 

[robnitro]

I'm not sure but I've read from an older post by JSRMonster, that the max safe QA is limited by the QA mechanism itself. I believe the hard limit is 4.5v. To get more fueling beyond that, you run bigger nozzles, or higher pressure. The pump still thinks it's doing 51, but flows more.

http://forums.tdiclub.com/showpost.php?p=1876462&postcount=2

Hi,

Set the metric at 32768 and hammer the QA to read 3.5mg/stroke (engine hot, AC/defroster must be off, idle at 903). If QA is not adjusted correctly (hi or low), it throws off the max duty cycle for Q-adjustor (QA collar position - analogous to TBA adjustment with throttle body on gas cars). ie. when asked for 4v, it it has to make up 0.1 volt given by adaptation, it will only give 3.9v final position. This is no problem for part throttle, but full throttle will be cheated by incorrect full stroke/position. See the wot QA voltage in vagcom field 1, ie. 4.0v at 45mg/R, vs 3.9v at 40mg/R. Flip side is lowering IQ too much will give too much voltage, and can shut down (limp mode if more than 4.3v, like tuning boxes and evry mods, etc.) Just like gas injectors if you pull too much pulse witdth/voltage, it will kill ecu drivers from too much voltage/current. When the QA moves the collar and uncovers the piston fuel delivery hole, there is no way more voltage can uncover a hole more then it is already fully uncovered.

Please don't hammer mod unless you know what you are doing. I often have to fix this cuz some unknowing mechanic decided it was necessary to fix smoke. This doesn't fix smoke, it only detunes your car. Smoke is usually clogged intake/exhaust or boost/vaccume problems, unless someone has obviously mismatched heavy fueling mods to turbo's capability.

This is also true for timing and start of injection duty cycle.

You can see the duty cycles in vagcom.

Jeff

 

[bhodgkiss]

Thanks

I don't want to be messing with the pump hardware.
I guess if I'm at max fuelling with the 0.205 nozzles its time to put the R520's in??

 

[robnitro]

A BV43 can run some like 26-28 psi, right? If so, yeah normal 0.205 nozzles are too small. I'm on VNT 17 with 23 psi, and Titan .234 nozzles do well for me, upgraded from .216. What I was able to notice is that I was able to pull harder to redline than before.

Recently indigobluewagon got headwork done and dynoed his car. Because his PP520s were too small, it ended up flattening his HP curve compared to his last setup.

 

[brum]

So is there some voltage limiter in the ECU or not? AFAIK - no, as I've tuned ECUs to request up to 4.9V (EDC15v). But it looked a bit strange as I didn't saw much difference compared to 4.5V even the ECU reported proper pump voltages in 1st channel of the diagnostic data. When I tried requesting 5V the ECU went into limp mode for a moment and stored a fault.

And about the duty cycle for QA - there is a PID taking care for the deviations. All I've seen till now was a tunes to the pump voltage map without touching the precontrol maps. And the ECU was able to achieve the specified voltages easily.