TD5 waste gate actuator operation

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Originally Posted by sierrafery

Where did you pick up the boost for the gauge?

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At the moment my WGM is bypassed and the boost gauge is connected to a 'T' before the MBC. After a few failures in the past (hoses softening and splitting or slipping off) I switched to using fuel hose for all waste gate related piping. For the boost gauge hose I used black nylon pipe and brass connectors from a VDO oil gauge connection kit.

As we can see this boost controll thing is more complex than it appears, i made many live tests on my car with all kind of setups(even MBC+WGM) and even though at the beginning i started with shortening the rod untill the overboost limit i realised in time that it's a crude solution and the longest the travel of the diaphragm is the smoothest the boost curve is as well, that's why i went for the forge actuator which has a more ''gentle'' actuation and my car runs better with the Forge - WGM setup than with any other

i asked about where the boost gauge is getting the input from cos i observed that the best is to pick it up from the EGR bypass pipe cos if it's close to the actuator the difference in reading compared with nanocom is greater

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Originally Posted by sierrafery

i asked about where the boost gauge is getting the input from cos i observed that the best is to pick it up from the EGR bypass pipe cos if it's close to the actuator the difference in reading compared with nanocom is greater

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But if its hooked up on the hot side this can allow you to measure pressure drop across the intercooler, so you'll be able to gauge when it should get a cleanout, or if an upgraded intercooler worked well ( as long as no boost box fitted :-)

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Originally Posted by onebob

Thanks for the input Offtrack, the 'early opening' is i think otherwise referred to as 'waste gate creep' and that's what i was alluding to in my 2nd post re shorting the rod being a crude solution that worked somewhat!...'somewhat' alluded to the waste gate creep that i suspected was occurring. Pre MBC the boost gauge needle would rise to a level relevant to my throttle position and then fall back a few psi now with the MBC the needle rises swiftly and holds position and boost is sustained until throttle position or engine load changes.

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It's not really "wastegate creep".

The plot below show what I'd call wastegate creep. This is with the WGM switched off in the map, and 13 threads exposed.
You can see the boost climb steeply until about 100kpa/14.7psi then as the waste gate creeps open, boost slowly continues to increase to 124kpa // 18psi.

Attachment 129701

The next shows the kind of peak and droop that you get with stock WGM configuration and arm wound up a few turns.
It happens because the boost peaks when the WGM duty is at maximum meaning the actuator is seeing reduced pressure. As the WGM controller corrects what it considers higher than required boost it allows more pressure to reach the actuator resulting in a drop in pressure. So it's not creep - the final pressure is where you have actually set your waste gate to open, and the peak boost is overshoot.

Attachment 129702

What I'm playing with at the moment is adjusting the maps to control the wastegate using the modulator as a EBC.
At the moment I still have part of the controller disabled as I'm trying to establish a baseline for duty cycle.


Attachment 129709

It's working quite well, but is a long way from done.

Just a quick question if I may regarding installing a MBC
Tee off in the line between waste gate module and waste gate??
Like this??
https://www.aulro.com/afvb/images/im...017/09/528.jpg

I did try MBC in line but just couldn't set with out going into over boost??

Cheers Lemo

No .... that's not how an MBC is intended to be installed. Sorry but unable to respond with more detail until this evening...

If you want to mix the MBC with the WGM install it before the WGM on the pipe which comes from the intercooler, then it should work.... at least worked for me when i made various tests but i used a ball/spring type like this TURBO MANUAL BOOST CONTROLLER - BALL AND SPRING VALVE! | eBay not the bleeder version

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Originally Posted by sierrafery

If you want to mix the MBC with the WGM install it before the WGM on the pipe which comes from the intercooler, then it should work.... at least worked for me when i made various tests but i used a ball/spring type like this TURBO MANUAL BOOST CONTROLLER - BALL AND SPRING VALVE! | eBay not the bleeder version

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^^ That or bypass the WGM entirely.
Given the WGM is doing nothing useful in this configuration, I'd be inclined to bypass.

Bypass is what I've done ...

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Originally Posted by OffTrack

^^ That or bypass the WGM entirely.
Given the WGM is doing nothing useful in this configuration, I'd be inclined to bypass.

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Maybe in theory it doesnt but in reality it does cos i tried both ways with drive tests and with the WGM in situ the throttle response at low revs was better and the boost built up faster than without it also with the MBT set as the final MAP reading with WGM + MBC to go up to 240 without touching the MBC just bypassing the WGM the MAP never got above 225 in the same driving conditions, i can't explain why, maybe there is a certain restriction through the fully opened WGM too...IMO the WGM does it's job the same way just that the actuation boost is lower as restricted by the MBC... i can't and i dont want to contest your research but that's how it happens i can vouch for that

what i can tell based on my drive tests is that the actuator's spring load is also very important and makes a difference even with small adjustments... at least that's obvious with the forge actuator cos all my tests were made with it