Can a manifold cause overboost?

[player69x]

I recently changed my turbo from the stock t25 to a FPR big t28 the car was running fine but my manifold had a crack in it so it would backfire through the crack whenever i changed gears. I changed the manifold and i put on a evo 3 manifold on the car. Now whenever i step on the the gas the boost guage goes all the way round to 17 and the car doesnt move like im at 17psi, i always let the gas go before it goes any further than 17. It still does the same thing even when my boost controller is turned all the way down. Is it the manifold or is the the boost controller or is it something else?

 

[brenden3010]

Check the spring in your Boost Controller, some cheaper ones get stuck on the threads inside. Chances are, it may have gotten stuck compressed.

 

[justin_5585]

start simple and check all of your vaccum lines incase one was left off or misrouted in the swap. Then do a boost leak test to see if you're losing air somewhere. Are you hitting fuel cut at all? What are your mods? Your list in your profile needs to be updated so we can better help you.

-justin

 

[player69x]

all vacum lines are connected propperly i just changed my engine and my intercooler and piping i checked for leaks when i was changing it. my mods are big t28, ajustable fuel pressure regular,full apexi exhaust from the turbo back, walboro 255 and a manual boost controller and no i did not hit fuel cut and i always let go of the gas before i get a chance to hit fuel cut i dont want to blow my engine.

 

[justin_5585]

and you're on stock injectors and no tuning system correct? You said the car doesn't move like your at 17 psi, correct? You don't have a data logger? When you say you checked for leaks, you visually inspected your couplings, or you actually built a detector and pressurised your pipes and checked for leakdown? what kind of boost gauge do you have? Are you on stock intercooler and pipes? BOV? a stock 2g definitely can't hang with 17 psi, it's been known to blow open with as little as 14.

 

[player69x]

I have a aftermarket bov and a upgraded front mount and no the car is not tuned. If the car was leaking it would not go to 17psi ive had leaks before. The car was hitting 15 psi before i changed the manifold without problems all i did was take the manifold off and replace it with a new one.

 

[player69x]

Can someone please help me.

 

[elfroggo]

You were visually inspecting or inferring that because you built 17psi you don't have boost leaks.

Do a real boost leak test.

Remove the MBC and hook up your boost source directly to wastegate and see what boost you get.

 

[justin_5585]

Again, what kind of boost guage are you relying on for this reading? Where is it tapped in at?