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The Trouble with Stuck Actuators..*with graphs!*

ragpicker

Well-known member
Joined
14 Apr 2013
Messages
4,062
Hey,

After my cars dismal display at Vmax I've been thinking about things. I did a few datalogs which were depressing to say the least and (to my mind) showed a boost leak because the requested boost would not ever be delivered. I dismissed this because I'd checked for leaks the day before travelling down to the event.

Anyway yesterday I finally got time to re-check. Sure enough, the bottom pipe off the T-Piece which leads to the DV's had come off completely. With this fixed I went out to do some more logging.

The car felt immediately noticeably more powerful but was reading more boost than ever before. After a couple of pulls I heard some knocking and then all power was lost but with the engine running. Suffice to say that I coasted to a standstill with the car struggling to idle. I thought I'd blown a hose but turning the ignition off and on again restored the car to its former glory. I presume the ecu detected some severe knock and pulled the plug.

I got the car back home and found the previously un-siezed passenger side actuator, completely seized again.

Heres the graph of what happens to your boost when your wastegates don't open. Obviously this causes the engine to run very lean and risks knocking and potentially grenading the engine. I'm going to try to unseize it again but I'm going to get the rod into the exhaust housing (where it has seized) drilled out and replaced asap.

16576130623_eed557981f_o.jpg


ETA: The X-axis is RPM. The Y-axis is pressure in mbar. To figure out the 'bar' of boost requested, take 1000 off the value and then add a decimal after the '1'.

Requested boost is usually around 1-1.2bar, actual boost is 1.5ish bar (because the one working wastegate cannot dump enough boost to bring it back down to requested levels)
 
Loving this logging this morning!

Here is a graph of the engine load in arbitrary units vs RPM. This can be used to compare the power outputs of various cars as the ECU units are always the same (as opposed to dyno's units). As far as my limited knowledge goes there is no real way to convert to torque but it closely matches a torque curve.

Anyway, you can see what a massive difference a small boost leak makes!

17010375329_d521e979fb_o.jpg
 

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