VCDS Injection Quantity Adjustments


Active member
Oct 9, 2012
Golden State
TDI- B3V, B4S, T4 , MK1
I started to play around with the IQ made sure I was starting at the 32768, then I hammer modded it. Now I am sitting around 3.2-3.4 mg. Now back in VCDS I adjusted it to 32686 which brought me to 4.6, but I can not lower the number anymore, won't let me save. Online I see others dropping the number lower and getting above 5.0 mg but I can't, are there other limiting factors?

Forgot to say the max I could get from the hammer mod was the 3.4 , maybe I'm doing something wrong there. Some people said there are getting 5.0 just with the hammer.

MK3 AHU stage 3 tune


That helpful B4 guy
Nov 10, 2007
Relocated from Maine to Dewey, AZ
Only the B4V left
The VCDS adjustment has limits, which is about 1.0 mg/L. Other than that you need to hammer mod it. I'm not sure why you could not, I have adjusted cars from 1.0 to 9.0 when hammer modding them without issue.


teh stallionz!!1
Nov 27, 2004
cape cod, ma
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
it will very much depend on the tune how much the "IQ" number changes for the amount of hammering, but the max range of IQ adaptation is from 32784 (maximum amount to LOWER IQ) to something like what you said - 32686 - which is the most you can RAISE IQ - with adaptation. the numbers you are changing are essentially injection durations (pump voltage), but its applied across the board. so -30 to IQ adaptation is basically like hammer modding UP by .03v. adding +30 is like hammer modding DOWN bye .03v - if you are looking at pump voltage in 001

the less pump voltage needed means the QA has been hammer modded to increase durations with less applied voltage (hammering down). when the tune sees this, it is then reported IQ to be lower. you have now effectively increased the fueling by a linear amount across the board