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About to play with quantity adjuster... any advice?

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Have just changed the injectors over and have cleaned everything inside the pump. New seals and everything is god to go. I was about to start messing with the QA settings (everything is still factory- but a bit out), but thought I'd see if anyone on here has ever been brave enough to get stuck in. I know you can change the injection start point, but the servo mech in the pump can be 'tweaked'.... Can't believe how much metal material was stuck to the magnet  (for the servo motor arm).

On the same subject, does anyone know how the adaption routine works?

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Well I've nudged the servo assembly over to the right and now we're idling at about 2000 rpm. Huge increase in power/torque. So I need to drop the revs using Skezza's adjusting thing... Will keep you posted.

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On a side note i have the SDI map and it's got all the maps needed for a turbo just sitting there, so shouldnt be too hard to turbo one. pump adjustment and voltage maps etc too obviously.

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I can't think how the other fuelling maps could be accessed on a SDI. I mean the only inputs are rpm, temps, pedal and injection begin/end. Looking at how the pump works, it doesn't take a rocket scientist to realise that the amount of fuel to inject per stroke is primarily determined by how far to the right the 'dump ring' (as i call it) is shifted. More right, more fuel. Left, less fuel. The rev limiter is 100% electronic. If i had a spare pump, i'd be tempted to rig up a cycle brake cable or somthing a make a manual throttle as an experiment. The ecu would throw a wobbly, as the engine would be doing exactly what was demanded by the driver..... i'm amazed at how simple it is.

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Ok, so I've tried to figure out if these settings are right (without any reference sources). See screen shot.

There's an adaption setting somewhere, which I believe can be changed to alter the sensitivity of the throttle servo- something like change 32768 to 32700? But where is it???

Right now the car is completely gutless, but the QA adjustment is right. I think the upper servo pickup reading is low however. Before I unscrew the top of the pump and adjust the sensor arm position, I'd like to try the adaption routine. Think it may do anything?

QA settings.jpg

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Pump volts and IQ look right.

pump volts.jpg

Copy paste from another forum for A4 tdi:

----------------------------------------------------------

Group 019 (Quantity adjuster)

Voltage from modulating piston displacement sensor: 0.500 - 0.970 V 
Voltage from piston displacement sensor: 4.150 - 4.740 V 
nothing
nothing

If specfied values are out of tolerance, possible malfunction of the injection pump quantity adjuster.

-----------------------------------------------------------

ideally you need the spec for your pump

 

Edited by Sausage

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That's a really useful plot. Awesome info!

Yeah the pump is the same across the entire range- i think the VE diesel pump is used for lots of makes and models. The only thing different physically are the addition of a turbo or different injectors. Our SDIs use 5 hole 0.170 size nozzles. The settings should be about the same as a 1.9 SDI or TDI, as at idle the engine drag is about the same. They all need about the same amount of fuel feed to keep the RPMs at about 920.

So maybe my measurements of 0.620V to 4.380V are ok after all. Before i shifted the servo mechanism to the left the readings were different, like 0.60 to 4.7. I had a lot more power, but the IQ was about 11 or 12, which is obviously wrong. The hammer mod is great, but it only tricks the position pickup sensor. I don't think the IQ quantities are measured at the no. 3 injector (even though though technically it would be possible)- the numbers shown in Vcds are calculated form the map. But i just don't know for sure. 

When i get time, i'm going to plug into my other SDI and get some readings (that car runs like brand new).

Do you know how adaption works, or where to change it?

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Just had a closer look at that map table... if you look at the max servo voltage, upper reading it measures 4.380 volts. On the map chart that equates to about 27 milligrams per stroke of fuel. The max fuel per stroke at top RPMs is about 51, which clearly explains why the car is gutless, running only about half power! To get maximum fuelling, that upper measurement 'has' to be at least 4.50 volts...

I'm not sure, but i think the only option is to adjust the servo pickup arm position, by moving it clockwise. Undo locknut, move then tighten up again and re-measure eveything.

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No not really, that is one of many maps that limit the engine, it will take the lowest of several maps under different loads and conditions.

Here is drivers wish (pedal %)

 

sdi DW.jpg

here's another Torque limit (to protect gearbox, clutch  etc)

 

sdi torque.jpg

Your engine is atmo so will only be able to handle around 27mg of fuel.

It may be that some of these maps are redundant anyway depending on how mechanical the pump control is, so just because there are maps for things doesnt mean they are doing anything on an SDI. (it has turbo maps after all in there)

Edited by Sausage

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Uh, ok. Any suggestions on how to get my power back to normal...? I'm sure its something to do with adaption, but i've never played wuth that on an SDI.

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Pump timing external and internal (if you rebuilt pump), pedal /TB, IQ adjustment? 

Here's the hammer mod but i assume you have read this or similar: http://www.myturbodiesel.com/wiki/injection-quantity-adjustment-fuel-pump-hammer-mod/

I assume it is similar on SDI pump.

Pedal / throttle body (dont know is SDI needs this): http://wiki.ross-tech.com/wiki/index.php/Throttle_Body_Alignment_(TBA)

Why have you done injectors and pump anyway? I assume a problem. You need a baseline before making changes otherwise you dont know what is wrong.

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So here's the history to explain all my madness... over the last year.

Engine sounded ok but occasionally when hot there was a distinct ticking or pinking sound, as if it was injecting too early. So after messing with pump timing (no effect), running a purge and changing all filters, came to the conclusion there must be a blockage in the tank. Engine was now down on power by a lot and ticking noise all the time (I have two SDIs so can compare easily!). So checked the strainer in the tank. No air leak in fuel lines either. All fine. Hmm.

Must be the injectors. So whipped them out and after giving them a good clean, took them to a local place that has an injector tester. All five ports on each injector just fine. All good there too. Chatted with the diesel specialist who thinks its dead cert that the pump has had it. After 92k miles?!?

So after much research things started to point to the quantity adjuster servo system being out of whack which can happen apparently (according to interweb).

Ok, so out with VCDS last week and sure enough the injected quantity reading per stroke was way too high at idle- like 10mg. Did the bump (hammer) mod thing (as it's called!?!)- or servo position adjustment as I call it, and nudged it down to 4mg. Drove cr and definitely an improvement, but still very much down on power. So as an experiment, nudged it right over to make it idle at 2000RPM when hot, and my god my SDi turned into a rocket ship. Way more power than stock. Ok, so IMHO the pump must be ok.

So, I conclude that there is a problem with the QA servo or something related to that. I'm guessing that the servo pickup is telling the ECU that the amount of fuel delivered is too high, so when I demand full power, it thinks I'm getting a full load of fuel, but in fact the pump is delivering probably less than half.

So this evening I whipped off the top of the servo head to see what s going on in there. All looks ok. Clean and no jams or anything. I watched how the ECU calibrates itself on powerup, to get the max, then min voltage limits, so it knows where the arm is sitting, in relation to the fuel dump ring on the pump shaft. So I thought if I can change those measurements, I should be able to shift the idle point and subsequently the max power point. There is a calibration reluctor ring on the left side of the horseshoe pickup which you can move to change the limits- see pic. Tried changing them to max then min, while doing the QA injection calibration to get idle back to 2.8mg, but still no change. I'm just about out of ideas!

So presently the idle setup is like below. I did notice that the injector variation is quite high which I'm a little concerned about- it might indeed mean my pump's knackered. other pic.

 

cal ring min max.jpg

variation.jpg

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