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Mac Valve is it buggered


Matthew Ball

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hi ihave a plug in g4x on rb25det i have used the boost valve wiring harness aux8 i am attemting to set up open loop boost i have it set on high side driven as if its in low side i get fault come up if i try test it i get fault in the on position and if i use pwm i can get it to flash on and off its set at 20hz it will flash fault on and off when i set the test hz to 1 if its at 20hz same it just holds fault i tried putting the rpm to 0 and ive got the table on tps as per link instructions and rpm if i push the pedal it go green the fault red im not sure what im doing wrong or if i have a faulty mac valve it works with 12v applied to it 

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There is no point using high side drive mode as this ecu doesnt even have high-side drive hardware fitted.  Change it back to low side drive.  With the solenoid unplugged/disconnected, if you then set aux 8 test to PWM, does the aux status still show a fault?  Or only with the valve connected?

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20Hz would be normal.  If it only faults with the valve connected then it suggests an issue with the circuit, either too much current or the voltage is low.  If you have a multimeter handy, can you measure the resistance of the solenoid.  

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46 minutes ago, Matthew Ball said:

When I put the multimeter on each wire 0.02ohms

If this is with just with one multimeter probe connected to one solenoid wire and the other probe connected to the other solenoid wire, then that solenoid has a dead short inside, it is faulty/rubbish.  

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11 hours ago, Matthew Ball said:

make about the 5.2 to 5.7 out of the loom ecu is that normal

Yes, normal.  In PWM test mode the output will be pulsing between 0V & 12V at 50% duty cycle, the multimeter isn't fast enough to show this so it will display roughly the average of the two voltages. 

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Replaced Mac from advice that it was no good  still have fault showing when plugged in or on pwm test if I have it set to on in test fault goes away and I get active when I push the gas pedal  ??? I've set 0 rpm for active and 90 kPa  for activation so I don't have to keep starting the motor  it's a g4x plug in on a rb25det it is wired to the standard boost solenoid wires 

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If you set aux 8 test to PWM and set the frequency to 10Hz, can you hear the valve clicking?

 

1 hour ago, Matthew Ball said:

I've set 0 rpm for active and 90 kPa  for activation so I don't have to keep starting the motor 

The boost control function will only activate when the engine is running and all lockouts are met.  

 

1 hour ago, Matthew Ball said:

still have fault showing when plugged in or on pwm test if I have it set to on in test fault goes away

This would suggest it is failing the open load test.  The ecu checks the voltage on the aux pin when the valve is "off", it expects to see something close to battery voltage.  So iIt sounds like you dont have 12V on the supply side of the solenoid.  

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On 6/11/2024 at 10:55 PM, Matthew Ball said:

im getting 11.89 volts no valve clicking

Can you explain how/where you are measuring this?  The only explanation for the reported fault would be the incorrect voltage on the supply side of the solenoid.

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If the ECU is connected and powered on then you will see near battery voltage on any Aux output that is not pulled low, this means that if you measuring with a multimeter while the solenoid is unplugged you should see battery voltage or near it on both sides. If you set your Aux 8 output to test On and active low and then measure again you should have one pin as ground and the other as battery voltage.

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Hey there I'm after anything else I can do to get the Mac valve working I've tried everything that has been suggested apart from trying it on another aux position on the ECU I'll try that and get back to the forum mean while any suggestions would be great 👍 

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is it normal for aux8 to turn to active when the dbw is turned to run throttle even though nothing is connected to  aux8 it was for mac valve which still wont work by the way link plug and play external dbw module g4x rb25det still getting fault with mac connected 

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