boost falling off

[ilikebigbutts]

so i got my mbc installed and i have it set at 9 psi for now.i notriced today that in second gear i'll get 9 psi at around 3500ish rpm but it will fall of to 5 by red line.in third it wont to it as much although i havent redlined third yet.what could be the problem?boost leak?i have a 3" elbow back exhaust, could my stock elbow be restricting me?or is it my tired wastegate?i got 5si max before i installed the mbc out of my wastegate.

actually, i just got all the parts to make a booost leak tester, i'm gonna try and finish it tonite.

 

[s383mmber1]

Sounds like a real tired wastegate to me....

 

[ilikebigbutts]

i switched this waste gate over from the blown turbo that came with the car because i didnt know if i trusted the waste gate that came with my "new" turbo.the guy blew the turbo cus he was running 14.5 psi with it.i'm guessing shitty wg too

 

[gravesdu_99]

Does anybody make new springs for the ct-26 or has anybody justed a spring from a different wastegate.

 

[GuNDeZZZ]

Try shimming the wastegate and see if that conforms the bad wastegate idea

 

[MKIIINA]

if you are running the stock dp and a stock turbo and have an old tired wg its a triple threat boost issue.

1 shim the wg as suggested
2. get a widemouth elbow
3. get a bigger turbo as the ct tends to run out of breath up high

 

[GuNDeZZZ]

if you are running the stock dp and a stock turbo and have an old tired wg its a triple threat boost issue.

1 shim the wg as suggested
2. get a widemouth elbow
3. get a bigger turbo as the ct tends to run out of breath up high

yeah true..... with out a "turbo back" you wont get the flow out quick enough.....

 

[gravesdu_99]

I've got a Megan 3" downpipe with a custom 3" exhaust and a cone filter and it still does it.

 

[GuNDeZZZ]

probilly a bad wastegate shim it and see what happens....


if i do my swap in the next few weeks ill be parting out my 7m ill let u know if it turns out to be ur wastegate...

 

[89turbotoy]

i switched this waste gate over from the blown turbo that came with the car because i didnt know if i trusted the waste gate that came with my "new" turbo.the guy blew the turbo cus he was running 14.5 psi with it.i'm guessing shitty wg too

chances of having 2 bad wastegates is pretty slim. you most likely have a boost leak. i had this problem once when i first bought my car and had a mbc and it was a leak where the plastic elbow is it had a small crack. it could also be a bad bypass valve.

 

[AaronsSupraMKIII]

Sorry to hijack the thread, but when I boost, It will just boost for a few seconds then goes back to vaccum. How long should it stay boosting when I accelerate? I think I have some problems...

 

[GuNDeZZZ]

it will boost as long as u are on the gas....... your turbo sounds like it may be crapping or a major boost leak or a crappy wastegate......

unless the gauge or sender unit is messed up.....


:aigo:

 

[AaronsSupraMKIII]

it will boost as long as u are on the gas....... your turbo sounds like it may be crapping or a major boost leak or a crappy wastegate......

unless the gauge or sender unit is messed up.....


:aigo:

My turbo has no shaftplay and I have a really good boost controller, I think it is my wastegate. It might be a boost leak to though. I will try and shim it when I get some time. I work 7 days a week, and its been so hot I havent felt like dooing much. I havent even messed with the other supra at all since I brought it home. I really need to get my DD running right though. lol
Its my first turbo, so I just didnt know for sure if it was supossed to boost when I am on the gas, or not, but I figured it should boost alot more than it does now.

 

[s383mmber1]

Turbos work with pressure, as long as theres a certain amount of pressure, there should be boost.

 

[ilikebigbutts]

chances of having 2 bad wastegates is pretty slim. you most likely have a boost leak. i had this problem once when i first bought my car and had a mbc and it was a leak where the plastic elbow is it had a small crack. it could also be a bad bypass valve.

no i meant i havent used the other wg that came with my new used turbo caus ei didnt trust it.i just got back home visiting the gf so i didnt have time and tomorow i work all day but tues or wensday i'll check for leaks and if there are none i'll put the other wastegate on.