Quantity Adjuster N146 Problem Solved!


Jul 7, 2015
Freeport, Illinois
2000 VW Jetta TDI
Hey guys, I wanted to share this in hopes that it will help somebody else down the road.

Last week a customer brought me a car needing an injection pump as it sounded like it was going to explode at any second with some very nasty clicking, clanking, and ticking. He supplied me with a used injection pump that he assured me was working well when it was removed from another car.

After installation of the pump with timing reset, and priming of pump and injectors the car started right up, but did not want to rev at all. I checked the IQ and it was sitting around 2.3mg/str (slightly lower than I like, but not crazy). I checked the injection timing and it was directly on the blue line. after about 5 minutes of mind boggling, it finally did something when I touched the accelerator. It revved up sporadically and started to idle terribly, surging and sputtering and revving uncontrollably. The IQ was jumping from 0.0mg/str up to 9.0mg/str and injection timing was jumping all over the place and a flashing glow plug light and check engine light.

It also produced the following:
3 Faults Found:
17970 - Quantity Adjuster (N146): Upper Limit Reached
P1562 - 35-10 - - - Intermittent
17971 - Quantity Adjuster (N146): Lower Limit Reached
P1563 - 35-10 - - - Intermittent
17969 - Quantity Adjuster (N146): Control Deviation
P1561 - 35-10 - - - Intermittent

I decided to pull the quantity adjuster cover off to watch the QA work as I cycled the key, and here is where I found the problem. The QA should quickly cycle to WOT and back to the starting position, this one did NOT move quickly, or even do the cycle that it should do. It slowly fluttered a little and settled to the starting position. I immediately found this to be weird so I tried to move it by hand and what I discovered explained the sporadic reaction to the accelerator. The QA was gummed up, it could barely be moved by hand and returned slowly, taking about 6 seconds to return from WOT to its resting position. It is supposed to just snap back immediately under spring pressure. This slow reaction by the QA was delaying the response from the computer and not allowing it to settle into a controlled state.

I removed the QA and was able to spray some WD-40 into the moving part from the bottom side and got it to limber up and snap back under spring pressure as it should. I assume that this pump had been sitting around a while and the biodiesel got gummed up as it is known to do in injectors when they sit. I re-installed the QA and started the car and it ran perfectly. I performed the hammer mod to get the IQ right at 3.5mg/str, slightly advanced the static timing closer to the green line, and when the customer showed up we took it for a test drive and his response was "wow, this thing is so quiet it is like a whole new car!" I told him that the way the previous injection pump sounded I actually pushed it by hand from where he parked it to where I was going to work on it because I didn't trust it's longevity, and did not want a broken timing belt under my watch. He assured me that he had driven it 50,000 miles with it making that noise! :eek::eek::eek:


Top Post Dawg
Mar 23, 2014
Abbotsford, BC.
2003 TDI 2.0L ALH, auto, silver wagon, lowered, Colt stage 2 cam, ported head,205 injectors, 1756 turbo, Malone 2.0, 3" exhaust, 18" BBS RC GLI rims. 2004 blue GSW TDI, 5 speed, lowered, GLI BBS wheels painted black, Malone stage 2, Aerotur
Its nice when a plan comes together. :cool:


Veteran Member
Apr 2, 2010
2002 jetta tdi auto converted to 5 speed. 2003 tdi jetta 5 speed.
I looked for bad wires visually, I did check resistance on pins 5 and 6 leading up to the ip. That checked out ok. I don't know much about injection pumps, but if pulling the top cover off would expose the QA then could I tell if it is jamed or something? I spent some time yesterday trying to learn how to read wiring diagrams on the Bentley witch came on the computer that I bought from the guy that sold me the 02 I still own and became quite frustrated. And the vag com is telling me that I need some kind of box tool to check some stuff to do with the p1562 code. And for some of the test the car needs to be running, well that's not happening yet. I have done a turbo, timming belt, cleaned intake on my other car but this one is turning out to be a real head scratcher. So I am glad it's not ergent to get it running soon as I am retired and have other transportation.