My MCX 180 has always run about 9 psi boost at 6500'. This weekend the thing was a rocket and I was shocked when the boost gauge read 14 psi. I babied the thing for the rest of the day and checked things out when I got home.
The waste gate moved freely and compressed air will move the actuator so that part is working fine. I think the problem may be the TCV valve. With no power on the valve, air can flow through the valve and out the waste gate port. However, air also flows out the bleed port.
When I add a 12v source, the valve closes and boost pressure can no longer pass through. The connection between the waste gate port and bleed port are open which I think is correct. This would allow pressure in the actuator to bleed off through this port and the waste gate can close.
I think there must be something wrong with the valve that is allowing air to pass though the bleed port and waste gate port at the same time. I don't know how this valve is configured, but it may have been damaged and is not closing the bleed port when it should. This could cause higher than expected boost levels. I may be out to lunch here, but this is all I can come up with so far.
I also checked wire continuity from the MCX box to the valve and it checks out. However, with the sled running at an idle, the voltage at the valve is about 7.6 V and the valve is open allowing boost pressure to the waste gate. Does this voltage sound correct? Maybe this valve should pulse open and closed to control waste gate operation and boost according to the map based on baro pressure, rpm, throttle position, etc. Maybe 7.6V is the low part of the pulse signal and 12V is the high that closes the valve. Not sure??
Any thoughts?
The waste gate moved freely and compressed air will move the actuator so that part is working fine. I think the problem may be the TCV valve. With no power on the valve, air can flow through the valve and out the waste gate port. However, air also flows out the bleed port.
When I add a 12v source, the valve closes and boost pressure can no longer pass through. The connection between the waste gate port and bleed port are open which I think is correct. This would allow pressure in the actuator to bleed off through this port and the waste gate can close.
I think there must be something wrong with the valve that is allowing air to pass though the bleed port and waste gate port at the same time. I don't know how this valve is configured, but it may have been damaged and is not closing the bleed port when it should. This could cause higher than expected boost levels. I may be out to lunch here, but this is all I can come up with so far.
I also checked wire continuity from the MCX box to the valve and it checks out. However, with the sled running at an idle, the voltage at the valve is about 7.6 V and the valve is open allowing boost pressure to the waste gate. Does this voltage sound correct? Maybe this valve should pulse open and closed to control waste gate operation and boost according to the map based on baro pressure, rpm, throttle position, etc. Maybe 7.6V is the low part of the pulse signal and 12V is the high that closes the valve. Not sure??
Any thoughts?
Matsofatso
Newbie
Well if its the same boost solenoid thats used on the phazer, theyre available on ebay brand new and for fairly cheap.
http://www.ebay.com/itm/Volvo-S40-S70-V ... 3f&vxp=mtr
Doesnt hurt to have a spare!
Just shoot Erik Marklund at mcx an email, good guy and he has been helping me out. Im sure he could give you some insight.
http://www.ebay.com/itm/Volvo-S40-S70-V ... 3f&vxp=mtr
Doesnt hurt to have a spare!
Just shoot Erik Marklund at mcx an email, good guy and he has been helping me out. Im sure he could give you some insight.
Thanks for the link. The Nytro TCV looks a little different. Maybe it is just the metal bracket that is different on the Nytro. I will email MCX and see what they have to say.
Vmax4
TY 4 Stroke Guru
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As I have been told, if you put 10 PSI of pressure to the EFI box (and plug the vac hose that normally leads to it) then you will hear the TCV flickering and fluttering. This is the test that I know of for that valve. I have also been told that if that isn't working, you end up with low boost........... (for the 270 kit anyways)
I have been questioning if mine is working properly either, since it was pretty high on the boost until I lengthened that waste gate rod a TON! And now it seems to stay the same boost in most any elevation.
Keep us posted on what you find.
I have been questioning if mine is working properly either, since it was pretty high on the boost until I lengthened that waste gate rod a TON! And now it seems to stay the same boost in most any elevation.
Keep us posted on what you find.
Dimebag
TY 4 Stroke God
You have to adjust the base pressure on the wastegate rod. If you lengthened the rod the boost will be too low.
If you dont have a boost gauge I would recommend you to install one before you start the adjustments.
If you dont have a boost gauge I would recommend you to install one before you start the adjustments.
Dimebag
TY 4 Stroke God
SNAFU said:
Bypass the tcv too see if the boost level drops.
Vmax4
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Dimebag what do you mean by adjusting the base pressure before adjusting the waste gate rod?
Dimebag
TY 4 Stroke God
There is a adjustment on the wastegate rod which is used to set the base pressure. You want the base pressure to be as high as possible (set for the lowest elevation you ever ride). Lets say you ride at sealevel with 15 psi, and at sometimes at 5000 ft. Then you want the base pressure to be 15 psi.
You turn the adjustment "screw" in to shorten the rod and increase base pressure.
You turn the adjustment "screw" in to shorten the rod and increase base pressure.
Dimebag said:
I think I will try connecting the waste gate to the turbo discharge directly as you suggested. I think I have narrowed it down to the TCV. What I really need to know is if the valve is open allowing boost pressure through to the waste gate, should air also be exiting the valve's bleed port? This is how my valve is currently operating so I feel that some boost is bleeding off and the waste gate isn't opening early enough. If someone can confirm the operation of the valve that may solve my problem.
If this is the problem, I'd like to replace the valve instead of installing a manual boost controller.
Vmax4
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To set my waste gate rod, I went out on a trail that was good traction at 6,000 feet and was wide and straight and smoot........
I set it for 17 PSI at that elevation. Had to screw the rod out to lengthen it about 5 full turns...... I am questioning why, but the TCV should INCREASE PSI when it "flutters" so I am told. So I am puzzled why I had to lengthen my rod so many turns.
Sorry to hijack this thread, but the two issues are kinda related in a way.......
I set it for 17 PSI at that elevation. Had to screw the rod out to lengthen it about 5 full turns...... I am questioning why, but the TCV should INCREASE PSI when it "flutters" so I am told. So I am puzzled why I had to lengthen my rod so many turns.
Sorry to hijack this thread, but the two issues are kinda related in a way.......
twiz28
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2017 Sidewinder XTX 137
boost pressure
I'm having similar issues. I have KOSO guage pod that Ulmer sold me. I can run up to 5500 rpm and still have - negative boost numbers at times, if I hold the throttle wide open the boost readings shoot to 9 or 10 psi. I'm running always below 3000 ft. This is a 180 kit as well. Allen suggested putting a mechanical guage to see if the the KOSO isnt faulty.
I'm having similar issues. I have KOSO guage pod that Ulmer sold me. I can run up to 5500 rpm and still have - negative boost numbers at times, if I hold the throttle wide open the boost readings shoot to 9 or 10 psi. I'm running always below 3000 ft. This is a 180 kit as well. Allen suggested putting a mechanical guage to see if the the KOSO isnt faulty.
Can someone answer this. When you start the engine, does the TCV solenoid energize (close) right away or not?
Just finished going through some emails with Erik Marklund who was a huge help. When sled is at idle, solenoid valve should be de-energized (open) allowing air to pass though it to the wastegate. The bleed port at the bottom should be shut. Mine is passing which is causing boost pressure to bleed off resulting in an overboost condition. Time for a new valve.
Dimebag
TY 4 Stroke God
If you find yourself in Norway one day, let me know. You can have my tcv too.
Glad you solved it. Erik is very helpful and knowledgeable.
Glad you solved it. Erik is very helpful and knowledgeable.
