Hello, I just completed my AHU build with AAZ pump. I chose the AAZ pump for now because I had it laying around, in the future I will change the internals to stock 10mm TDI or use the land rover pump if I get my hands on it.
The car starts and works fine but the only thing that seems weird is that when I rev up the engine the revs don't come down as fast as they used to with my old AAZ engine. I've been searching online for the cause but haven't seen anything yet.
Could it be because the pump has a smaller plunger and a different camplate compared to the original TDI one?
At the very first start, I didn't notice it but when everything went back together then I realized it and it seems kinda odd. Also, the small bolt on the fuel advance lever broke behind the pump and the cable went in too tight now the lever inside the car does not go the whole way out, can it cause the problem?
The pump is timed at 1.30mm and I'm running a K14 turbo. Only a little black smoke when I rev it up high (i think that's because I'm running a 1.6 td air filter box and it's restricting airflow, but on the AAZ it was fine)
What else should I check?
I also made a video where you can see/hear the problem:
https://youtube.com/shorts/6vZLuhUzfVgBest regards
The bolt that broke in the lever behind the pump is only a problem if it is advancing the timing on you. That is what that whole set up is designed to do. It does not add fuel to the system, it adds advance degrees, generally only 2 or 3 to help get the engine started.
Once the engine is running the normal dynamic advance will over take the few degrees the lever adds. So it really only works near idle.
Well the small bolt that holds the cable in the bracket broke but before that i accidentally pushed the cable in too far and now its too tight compared to what it was before, but it still works, if i push the lever in then idle RPM drops to normal and when i pull it out (it does not come out all the way as it used to) but the RPM-s go higher like they did before and everything seems to work fine on that part so i think its not a problem untill the cable comes out of the bracket one day.
EDIT: Today i noticed that RPMS work fine when engine is cold, they drop as soon as i let go of gas lever. But when engine starts to warm up then the rpms hang for a bit and then drop, as shown in the video.
Are you getting white smoke when you rev?
If so it could be a pissy injector.
I like clear fuel lines. Makes it easy to rule out air in the fuel.
No smoke at all, not even when starting the engine. Only very little black smoke in high revs but i think thats caused by the fact that im running 1.6TD small filter box and its restricting the air flow a little bit right now. But thats it
For anyone with same issue as me. I turned back 2 full turns the bolt that gas lever rests on (i think its called 'residual pressure' screw) when gas pedal is released. It fixed my issue for now and i hope it never comes back.
