quick injector/IQ question

[megaladon6]

i just swapped out my injectors stock for PP520's. they were balanced by Kerma. before the swap my IQ was 4.5, afterwards it was 3.5. this was without any computer changes.
is this normal? i thought the IQ was computer controlled and I had to change it, at least the computer value. i understand the actual amount of fuel will be different due to the larger holes.
thanks!

 

[Drivbiwire]

IQ is an "Assumed" value based on crank acceleration.

The Lower IQ number is the result of faster crank acceleration based on the original control collar position. The engine in effect is accelerating more efficiently than before to maintain 903 idle rpm, but having to use LESS control collar displacement (relative to range of motion) based on the fixed position of the control in the pump head.

Keep in mind that the new injectors are performing more efficiently than the older nozzles could, this is part of the reason the engine has to command less fuel to get the same engine rpm.

Make sure you do the following to "Complete" this tune-up:

-Advance the mechanical timing to the top of the range (70/110 in Basic Settings mode)
-Adjust the IQ using the hammer mod to around 4.5. (No haze to light haze no adjustment needed. Black smoke will require an increase in 1.0 increments until smoke is eliminated).

Perform a full throttle run, adjust IQ mechanically until you only see a light haze during full throttle acceleration. The actual IQ value will vary but the key point is to trim the fueling for the light haze. Black smoke is not acceptable. Generally the Flow is matched to your engine combination to permit an IQ range of 2.8-4.5 in your particular case.

The permissible range of adjustment on the IQ is 2.8-9.5 without creating any engine/ECU conflicts.

 

[megaladon6]

thanks for the great answer! i always thought the IQ was based on something like the physical QA position or the like.
unfortunately i now have a couple more questions.

when i did a quick test drive (IQ=3.5) there was no smoke or haze. i assume that i can lower the IQ to raise fuel until i get the light haze?

Also, as long as i can adjust to the proper range through VCDS, i don't need the hammer mod, correct?

timing--i've read the thread on timing. IIRC, the best place turned out to be where the actual and specified values were equal. does that hold/not hold true for bigger injectors? right now it's set just over the blue line, with actual/specified extremely close/equal.
thanks!

 

[Seatman]

There wil be a light haze, the exhaust tip bends down at the tail so you don't see it very easily but it'll be there. I wouldn't up the fuel any as I think that'll just be to much. As for the timing it's basically to get the torque band further up the revs, I had mine at about the 67 mark before and that gave me good power up near the 90 -100mph range, I've since knocked it back to around 55 or so and have lost that top end a bit but have more of a tendency to wheel spin. I'll probably go back further advanced in the near future though.
Here's a guide on the timing

http://forums.tdiclub.com/showthread.php?t=240450

 

[Bebuxa]

i my i.Q in my vp 90 hp alg is 2.8 in idle. i have changed noozles default to noozles tdi 110hp and my motor chakes, and because of that i reduce the value down...ist normal motor chake?

 

[sdeck]

I just had my injectors cleaned, pop-tested, pressures set, and new ULSD 520s installed on them from DriveBiWire. After they were installed by aNut, the IQ was set to around 4 via hammer-mod. Car had lots of power, but was a little loud and smoked some. It then failed emissions (55% opacity). It was black cloud under load on the dyno. Took it back to aNut and he whacked the IQ up to around 6.8. second emissions test was 5% opacity. Car is quieter, slightly more turbo lag, and has a very light haze under acceleration. NOTE: mine is an auto, so 11mm IP. Not sure if it makes a difference.

 

[Bebuxa]

why my motor is shakes if i set the adaption value 32768 and if i set the value to 32650 the motor dont shake? my idle mg/str is 2.8 mg str and the motor dont shake, but the value dont is low? i whant the value near 4 mg...any help?