2G Boost Not Holding

SlipGear · Oct 2, 2006

For a week or so my Boost hasnt been constant. It runs at different levels in ever gear. I am going to do a Boost Leak Test tomorow. Any other ideas of whats causeing the problem?

nightspeed87 · Oct 2, 2006

Well depends on how much your running, but like sometimes it will do that because there is a different amount of load on the engine per gear. Like the load increases every gear so therefore boost will build normally quicker in higher gears than lower gears....
But depends on how bad these sympthoms are that you have , more detail would be nice, like how much boost per rpm/ gear for example...

( Checking for a boost leak should be as manditory as changing the oil with these cars. )

OverBoostinGST · Oct 2, 2006

Check your mbc, boost leak maybe? I need more info to tell you really...............

andymoraitis · Oct 2, 2006

If you're running an internal gate with an MBC boost will naturally vary by gear since the load on the motor rises as the gears increase numerically. I have an external setup with no MBC and this is what I get:

1st: 22
2nd: 24
3rd: 25
4th: 25
5th: 25

Torque multiplication in 1st and 2nd will never allow my setup to hit 25 psi (even if I rev it to 8000 RPM). Go ahead and check your MBC lines for holes or leaks, but keep in mind that minor variances are normal. Weather will also have an effect since a warmer air charge or one with a higher water grain content will be less oxygen dense.

If you'd post what your specific boost levels are in each gear, that'll help us understand the problem more effectively.

Andy

Apeximprt2nr · Oct 2, 2006

I'm running the stock T25, and a Joe P. MBC:
1st Gear: 12 lbs
2nd Gear: 12 lbs
3rd Gear: 13-14 lbs
4th Gear:12-14 lbs
5th Gear:12- 15 lbs

It varies depending what RPM I hit the throttle on and gear obviously, as well as the weather like Andy already stated.

SlipGear · Oct 3, 2006

Well i did a boost leak test and none came up.
The Psi are as follows (all at WOT):
2nd:9-10 Psi
3rd:10-12Psi
4ht:14.5 Psi
5th:14.5psi

I took the MBC off and put the stock WGS back on to see if that corrected the problem and it didnt. I was wondering why it did this, because before MBC, Downpipe, and Test Pipe install it ran around 15.5psi in every gear. Wastegate is working fine. I am trying to run 15.5psi. I am never 10feet above sealevel and it acts the same day or night.

nightspeed87 · Oct 3, 2006

andymoraitis said:
If you're running an internal gate with an MBC boost will naturally vary by gear since the load on the motor rises as the gears increase numerically. I have an external setup with no MBC and this is what I get:

1st: 22
2nd: 24
3rd: 25
4th: 25
5th: 25

Torque multiplication in 1st and 2nd will never allow my setup to hit 25 psi (even if I rev it to 8000 RPM). Go ahead and check your MBC lines for holes or leaks, but keep in mind that minor variances are normal. Weather will also have an effect since a warmer air charge or one with a higher water grain content will be less oxygen dense.

If you'd post what your specific boost levels are in each gear, that'll help us understand the problem more effectively.

Andy

Like I was saying; this has to do with the different load imposed on the engine correct?

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2G Boost Not Holding

SlipGear

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andymoraitis

Apeximprt2nr

SlipGear

nightspeed87

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