Retarded timing at high RPMs on custom ALH 1.9

Long story short:

• GTB2260VK
• 0.370 injectors
• 12mm pump head
• Liftpump

For many months struggling with single issue - retarded timing after about 3k RPMs. It does run completely fine until full boost kicks in and rpms reaches ~3k, then actual timing drops and keeps jumping below requested.

If throttle is pushed just a little bit, i can get to max RPMS without any issues.

During all that time trying to find out root cause of issue changed like 3 pumps and broke 3 pump heads because plunger simply got seezed.

Main idea was lack of fuel at high RPMs. Since then fuel lines replaced from 8mm stock to 14mm, all restriction valves in tank completely removed. Now it is just clear 14mm hose from pump to tank.
All this work made slight improvements, but still timing is retarded, boost keeps flickering together with timing and totally no power because of that.

Case pressure in the pump is slightly above recommended. 8bar at idle and 13 WOT.
I believe that adjusting relief valve would improve timing performance, but then case pressure would be too high.

Did the tests without liftpump. With Mesmer 0.1bar 75LPH and pierbung 0.5bar 180LPH. Results are close to same except that pierburg produces to much pressure. at idle raised to 10bar with squeezing noise from pump. switched back to mesmer.

Timing without liftpump at all was close to the same, with only difference after 2/3/4 gears WOT pushing the clutch and engine stopped. had to roll in gear quite a big distance to get it up and running again.

Timing belt is set correctly.

Any ideas?

On the vp37 pump there is a pump pressure valve that need to be lifted up or it is broken and it is not working as it needs to.First you need to check if that valve is dissasambled and it if is not after that take it to it's place again and use small hammer to hit it just a little (FIRST 1MM)and after that check timming again if it if ok leave it like that if you need more use the hammer again and take it down to +1mm more

You are talking about relief pressure valve, and it is not broken.
Hitting it inside would make timing better, as well as it would increase case pressure in pump above 8/12 bar which is leading to seezing and broken plunger.
p.s. already broke one with 17bar pressure at wot.

three pumps doing the same thing?
rules out an awful lot of possibilities

Your case pressure measurement, is it while requesting full fueling or just no load max RPM?
Might find quite a difference between the two from the volume of fuel being injected.

I'd bet on insufficient supply side if you notice low case pressure at high fueling

Actually i already lost a count, but should be like 2-3 full pumps and additionally around 3 low pressure parts of the pump.
Behavior is almost the same upon all these changes.
Silly thing that first day or two after changing fuel lines to 14mm it was kinda fine, and in day 3 again problems.

Case pressure is 8 idle and 12/13 at full throttle in 3/4 gear.
Only time when it drops is after switching gears. then it drops to around 10 and quickly gets back up. Which could be explained with drop of RPMs.

It does look like insufficient supply, but... how? a lot of ppl are running even better sets with stock fuel lines, with all restriction valves without any problems.

could you have a clogged screen in the tank that has been there all along?

This was totally rebuilt with bigger hoses. Didn't made any big difference about timing.

Just like said it is hard to imagine what else could be a problem

Some additional thoughts:
* China pump head. Heard good and bad stuff. Well, i did tried like 3 heads already. But maybe indeed they are worse then OEM in tuff conditions. As known only upon @3k RPMS fuel pump starts to work at full power.

* Condition of pistons. It could and most likely IS affecting fuel burning process. Mine pistons have slightly melted fuel cams ( as far as it was able to see with camera ) Next week gonna change to PD bottom and will see actual condition. Overall it runs/starts/smokes fine. Compression also is normal.

P.S. don't buy HFLOX nozzles :/

I have no problems 12mm de143 dssr .360
Pd lifpump and 11 bar at 2000 rpm casepressure with 11mm timing cylinder and parts
18 degrees at 4000 rpm with 75 /80% dutycyle at wot runs

Yeah.. sounds good, also know a lot of projects that are running similar setups without any issues.
Hopefully bad engine block is RC of this issue.
I have 19deg@5300 RPM

Actually had a same issue with smaller turbo (1752) and .280 injectors.
After new turbo,injectors,exhaust with ecu map from previous one problem was gone.
aaand right after remap it is back again.

what pump you use the 12mmhead ?
the 11mm auto pump have better timing control sleeve inside pump

And mine casepressure is at 11 bar at 2000 rpm

the timing sleeve can get stuck by wear so dissamble the pump and check it

mine 18 deg till 5700 rpm no problems with reallt low dutycycle
at what basic timing you have im at 60, basic block vcds

try little more static timing block 4 vcds 3-4 degrees

what pump you use the 12mmhead ?
the 11mm auto pump have better timing control sleeve inside pump

And mine casepressure is at 11 bar at 2000 rpm

the timing sleeve can get stuck by wear so dissamble the pump and check it

mine 18 deg till 5700 rpm no problems with reallt low dutycycle
at what basic timing you have im at 60, basic block vcds

try little more static timing block 4 vcds 3-4 degrees

I think it had 10mm inside.
But well.. just like i said 3 pumps, i don't think that all of them were faulty.
Didn't tested pressure @2k, just know that idle it is 8 and WOT 12-13.

I'm kinda taking pump out of suspects, simply because this part was changed, repaired, checked like really A LOT.

If we would think about something else that could relate to timing?
What about needle lift? Crank speed sensor?
And yeah... no fault codes in ecu ofc.

12-14 bar is to low at wot mine see more like 16bar

if the pumpcase pressure drops than timing not good to hold, and high durty cycle.

try to raise case pressure a little bit and remove a remove a washer ring at the timing cilinder timing spring.
the spring holds back the sleeve and the case pressure pushing on it to get more advance timing

I have the same problem as yours.(1.9TDI 11mm, 0,216 and remap)
After installing 11mm pump head, I checked the timing and after 3k rpm is drop down. WOT with 4th gear 3k rpm - Duty Cycle is 91.1, 11 degrees, but 4k rpm - DC is 96, but timing going down to 9degrees.
I think this is my pump faulty, I changed the 11mm head together with pump, but still reading theses posts, I started to doubt it.
Case pressure is 6bar idle, WOT 4th gear 3.5krpm is 8bar. Too low?
Before installing 11mm, timing was perfect till 18degrees. Static timing 60.

Don't forget that the more effort you ask the pump to deliver fuel, the more counterforce it will have on the camplate, which will require more case pressure to rotate the carrier-to- timing piston. You can offset the pump mechanically with a special tune to go around this.

Hi guys any update? Im having the same issue with my AFN engine.... Can't pass the 330hp because timing goes down when i give it full throtle. I already have a external Pump installed...

im use dual pd liftpumps with Y piece, one pump im blockt the pressure valve and orther not.
Timing no problems. what timing you ask at high rpm
Mine frend do 350 hp vp with stock timing.