Boost Issue - Builds, Drops, Builds Again?

[1991TurboTalon]

I have a boost issue that I've noticed more in third or fourth gear. While WOT or Partial Throttle, my boost gauge (I have a an aftermarket GloShift, not the stock gauge.) reads that I build to 20-22 psi, it then falls off to around 15-16 psi, then builds again to 18-20 psi. What could be causing this issue?

 

[spawn87]

my stock t25 did that with my fmic in i switched it to the stock sidemount and it took care of it... but in your case it sounds like ## spiking and getting boost creep do u have a mbc? also have u done a boost leak test to make sure your system is not leaking?

 

[e85_4g63]

Yeah as strange as it may be, I also am thinking your getting a boost spike, and creep.

 

[1991TurboTalon]

Yes, I do have a MBC, its a homemade one, but always seemed to work no problem. My brother uses one built identical to it on his 2g. I have had a chance to do a boost leak test, my BOV was bad and replaced it the other day. I am going to get with my brother this week to do a boost leak test, he is in the process of moving. I have a EVO III 16g that is ported. Do you think my MBC could possibly be sticking?

 

[Drvlikeustoleit]

I think theres a good possibility that your MBC could be messing up. Did you use the aquarium valve procedure? I didnt trust the homeade method so I took it a step up and spent $15 or $20 on ebay

 

[spawn87]

i would agree the cheap ebays might be more reliable i went that rout and mine is still running strong...but get that boost leak test done to make sure everything is ok.

 

[1991TurboTalon]

Thank you for your responses. I will do a boost leak test, and change out my MBC with another one that is working... if it fixes my problem i'll have to step up as well. I'll keep ya posted after I test it out.