car hits 12psi then boom to 20psi

[negativezero27]

my car hits 12 psi around 3000rpm and then around 3400, it goes POP really loud through the exhaust and then it hits 20psi plus. I just checked my car for boost leaks and i fixed all of them. The only think that leaks air is my bleed valve mbc. my mods are e3 16g, fmic, 255,afpr, 680 injectors, new plugs and wires ngk bpr7's, turbo xs mbc, open 3inch dp. im just asking for ideas where i should start at. maybe i just need a good dyno tuning ?

 

[Spooling99]

Im willing to bet your gettin massive boost creep because of your open DP.

-Adam

 

[95talon_in_ma]

I'd try another boost controller to rule that out..
If it's good, I'd look into the wastegate side of things. Almost sounds like the flapper opens, then shuts.

 

[Sbeing1]

Could be your open downpipe, could be your flapper isnt opening enough.

 

[negativezero27]

well i just replaced my wastegate not to long ago because it had a huge dent in it. Before i replaced it, i could run no mbc and it wouldn't go past 11psi because the spring was hella smashed. Anyways, my car has been doing this before i took of my exhaust.

 

[Spooling99]

Check to see if your flapper is opening all the way.

 

[negativezero27]

i'm on it.....

 

[negativezero27]

okay, my wastegate opens and closes like normal.

 

[toomey200]

is your boost still jumping to 20 lbs?

 

[1990talon]

my freind had a simalir problem and it turned out to be the flapper it seemed to be operating normal when he checked it but it was hanging up just a little bit and he got that jump in boost like you.

 

[dieseltech]

i experienced a similar problem. the pop in the exhaust was a piece of muffler that deteriorated and would plug it, then POP it became unplugged. I'd try and monitor back pressure to see if it drops dramatically when it pops.

 

[GVR4592]

It seems like a pretty obvious case of boost creep, have you done any research on the subject? There's enough posts in this forum regarding boost creep to keep you reading well into 2008.

 

[negativezero27]

i found my problem. My a/f ratio was way out of wack. i got my car dyno tuned and its fixed.