Boost fluctuation

[Erlend / bug66]

Hi

What causes the boost to fluctuate between 1.65 and 2.00 bar at WOT?

If related, I can see my fuel gauge is fluctuating one the boost gauge the same.

[spanners]

Erlend, it can happen when the boost signal line is right on the compressor housing, probably you have a rising rate regulator/ gauge line off the same feed point so that sees the same pulses, when I moved mine to the inter cooler, the pulsing was almost gone, it's a normal function of high energy fluctuations from wast gate, engine breathing demand and exhaust pulses and wast gate breathing, there a ton of energy going on there as you know!  if it's bothering you try a damper in the hose like a T3 fuel line pulse damper, or even a good quality high pressure fuel injection in line filter like a Gti or similar, Bosch quality! that will damp it right down,  it is harmless tho but mine was quite noisy.

[Erlend / bug66]

Hi

Boost solenoid was feed from the pressure piping, regulator from 1 intake below throttle plates. Boost gauge and map-sensor share the same feed from intake #3 below throttle plates.


Does line diameter and hardness affect the pulsing? Quite hard vacuum lines.

Boost solenoid has braided AN3 lines.

[Erlend / bug66]

Will it help to have all vacuum lines from a "vacuum-box"?

One line from pressure piping to a box, and all auxiliaries connected to the same box.

[richie]

To me 0.35 bar[5psi] fluctuation is to much to be just be pulsing, that is enough difference to hurt parts.

Just throwing some ideas out there,

wastegate to small
wastegate spring to small and using boost controller to try hold boost up
turbo past its limits and surging
boost controller not working properly[ or if a good electric one settings not correct]

cheers Richie

[Erlend / bug66]

To me 0.35 bar[5psi] fluctuation is to much to be just be pulsing, that is enough difference to hurt parts.

Just throwing some ideas out there,

wastegate to small
wastegate spring to small and using boost controller to try hold boost up
turbo past its limits and surging
boost controller not working properly[ or if a good electric one settings not correct]

cheers Richie

Regulator gauge is pulsing even on idle. (rock steady with just pump going, without engine running)

Boost gauge is pulsing before wastegate should start functioning.

Opened the WG yeasterday and large spring is without color, small is red. Tial wastegate (forgot to check size, but 38 or 44)
- Only thing I found was that the diaphragm was pinched by the housing on one spot. About 1cm was pinched together. 

[Trond Dahl]

Your WG is 38.
Have you checked the solenoid to see if it is malfunctioning?

[Erlend / bug66]

Your WG is 38.
Have you checked the solenoid to see if it is malfunctioning?

Thanks

Nope. Thats on the list.

[richie]

To me 0.35 bar[5psi] fluctuation is to much to be just be pulsing, that is enough difference to hurt parts.

Just throwing some ideas out there,

wastegate to small
wastegate spring to small and using boost controller to try hold boost up
turbo past its limits and surging
boost controller not working properly[ or if a good electric one settings not correct]

cheers Richie

Regulator gauge is pulsing even on idle. (rock steady with just pump going, without engine running)

Boost gauge is pulsing before wastegate should start functioning.

Opened the WG yeasterday and large spring is without color, small is red. Tial wastegate (forgot to check size, but 38 or 44)
- Only thing I found was that the diaphragm was pinched by the housing on one spot. About 1cm was pinched together. 

Disconnect boost pipe to regulator and see if it still fluctuates with engine running, if so its reg or pump, if not then vacuum/boost related

[Erlend / bug66]

Any difference in connection map-sensor, regulator and boost solenoid over or under throttle plates?

[richie]

Any difference in connection map-sensor, regulator and boost solenoid over or under throttle plates?

I put map sensor & pressure reg/ blow off valve after throttle plate, wastegate is plumbed before, usually out of turbo intake housing

cheers Richie

[Erlend / bug66]

Thanks Richie.

I'll try to tee all ports together and tee off the lines I need after all 4 ports are linked.

If that works, I'll get a vacuum manifold