2.5 TD rattles, low power, low mpg

[67gtman]

Alfa Romeo TD engine although rated for 85 kW is hardly half of that. Completely mechanical.
- Very weak in hilly roads.
- Never gets under 8.5L/100 km.
- Rattles when accelerating.
Tore it apart last summer, everything in perfect condition. Valves, pistons,  hydraulic lifters, journals, bearings, oil pump. Turbo overhauled, newly balanced. After assembly, rechecked cylinder pressures, oil pressure with mech gauge. Timing is fine tuned from the basic setting. Injectors connected to fuel line spray fuel evenly while cranking the engine.
Still it has lack of power. Turbo pressure is hardly 0.5 bar even when wastegate is disconnected. 100% sure does not leak. Additional fuel at the top of injection pump rotated to the Max setting - yet other setting makes no difference. AUX fuel lift pump does not help too.
What else would your try?

[fatmobile]

Rattles when accelerating could mean the timing curve is wrong.
Rattle at higher RPMs?
 Might need to add a shim to the cold start piston.

[67gtman]

What timing curve? Your mean špring is too soft? Retarding it does not help. Hooked pwm controller to the pump timing solenoid, just lost additional power yet still rattled at acceleration

[fatmobile]

I'm not sure about the spring being too soft and allowing the piston to move to easy causing advanced timing.
 I had a 1.6 that got too clackity at higher RPMs and after I added a shim it stopped detonating.
 If setting the static timing more retarded didn't help I'm not sure the timing is causing the problem.

 Have you checked internal pump pressure @ 1000 RPM?
How's the flow rate coming from the pump, heading back to0 the tank?
Internal pump pressure drives the timing piston.
 
 Not familiar with this particular pump, is it computer controlled.
 Youy make it sound like the timing piston is computer controlled using PWM.

[ORCoaster]

If I remember correctly, there were different colored springs, green, red, blue and silver for the piston.  Green was the softest so it would advance sooner than the stiffer ones.  But just which one was the hardest to compress I don't remember. 

There might be something in the archives here or on the Hagar link. 

A stiffer spring would allow you to have more advance at idle without the fear of too much advance at the higher RPMs.

[67gtman]

Fatmobile... Your mean adding a pressure meter to the pump output will show its internal pressure?

The pump is mechanical, it has just this timing solenoid through which ecu momentarily cuts off fuel to the timing pistons to fine tune timing.

By the way, it would be nice to have a strobe timing light - flashing when current is induced in the 1st wired injectors (i.e. when nedele moves).

[fatmobile]

If you have a pulse detector you can use a timing light.
 That's what I use for setting the timing.

Yes, you can make a tool that allows you to see what the internal pump pressure is.
Basically a MK2 OUT bolt pedestal with a 1/8"NPT hole tapped into the side for the hose and gauge.
It's important to use the same OUT bolt as normal. You'll need a gauge that goes over 150psi.
 I think it's around 75psi @ 2000? maybe?
Since that's what determines the timing advance, it's nice to know.

 A Hagar trick was to measure the fuel flow out of the pump at idle and if the pressure is right, the proper amount will flow per minute.

The center of the pressure regulator gets tapped down to create more pressure. Probably not your problem.
 Also if the OUT bolt is clogged it will increase pressure in the pump, and advance timing.
Causing pinging at higher RPMs.

[67gtman]

It should read 75+- psi at the beginning of return line? Isn't it too much, especially for those little return hoses?

[fatmobile]

The pressure is on the other side of the out bolt.
 Before it goes through the restrictor hole.
If you put the gauge /hose on the pedestal the OUT bolt bolts into.