Boost issues

[DSM_TSI_95]

Im having a problem with my boost. I had it set at 10 psi but i turned it up to 16psi and ever since then it drops off to about 5psi but when i turn it up to twenty psi it drops down to 10 psi and it does this around 4000 to 5000 rpm. If anyone has any knowledge on this i would be very greatful.

 

[EclipseTrbo420A]

I would start wiht a boost leak test and also remove the MBC and see what happens

 

[DSM_TSI_95]

Yeah i have tried a leak test and came up with nothing i also removed the mbc and that didnt do anything.

 

[oldman]

Yeah i have tried a leak test and came up with nothing i also removed the mbc and that didnt do anything.

Describe your leak test process and results.

 

[DSM_TSI_95]

I tried the old soap and water method and i had a shop do the leak test for me as i do not have the tools for that. The results came back negative both ways. I dont think you toatally get my problem. Even if i set my boost back to 10 psi it will go to 10 and hold until the higher rpm range and then it will drop down to around 5 or so. I can turn it up to 16 to 20 psi and it will hold steadily there but once again at around 5000 it will die back down to around 5 to 10. I have never ran into a problem like this before and i have been around dsm's for awhile.

 

[EclipseTrbo420A]

If I were you I would not puch the stock fuel to 20 lbs especially on that 16g. as for your problem, It doesnt sound like you actually did the test...just spraying soapy water at idle of off wont show anything and to what PSI did them test the system I have seen leaks that brew only at a higher PSI. I would find someway to do a boost leak test on my own if I were you.

 

[DSM_TSI_95]

The tested it to 20 psi. Im not on a stock fuel system either. I know i dont have all of my mods listed on there. and i know you cant do a good soap and water method just at idle thats why i took it to the shop. Lack of tools is whats killing me on the prob and i wont get all of my tools back until sometime next week.

 

[DSM_TSI_95]

Okay well after performing the leak test myself and changing two mbc's I found out that is was the mbc. When i swapped the old one out the new one was bad also. Well thanx for all your help guys.

 

[EclipseTrbo420A]

What do you mean a bad MBC ? What was wrong with it >?

 

[DSM_TSI_95]

Well it was the turbo xs mbc. Those have problems. What it was doing was instead of allowing my boost to be constant at say 12 psi it would regulate it down even more. Its kind of hard to explain. I changed it out to a different mbc and it works perfect.