boost problem!!!! hits 20 and comes down.

[vsalas793]

hey guys i just had my car tuned with aem ems and made some nice power. i have the 16g evo III. 5 miles on it. didnt do this before. the boost kicks and goes up to 19 psi. and then comes down to 13-14. but its set at at 19 psi. its a brand new hallman boost controller. i replaced the current boost controller but it did the same. ne way at the shop they couldnt figure this out. so im thinkin if ne body has some advice.

 

[brute]

I think that's just your turbo. Evo16G's have been known to start to run out of breath before redline. That's why people usually shift at like 6000rpm.

 

[andymoraitis]

I think that's just your turbo. Evo16G's have been known to start to run out of breath before redline. That's why people usually shift at like 6000rpm.

Actually, that's not accurate. EVO III's are known to creep when the setting is low and then shoot past 20 psi. T25's are known for running out of steam. With a setting of 19 psi, I'd expect an EVO III to creep a bit higher depending on the exhaust setup, but not fall. Go ahead and do the following:

1. Boost leak test
2. Check the function of the wastegate arm
3. Look for excessive cracking around the wastegate opening
4. Make sure you don't have manifold or O2 housing cracks
5. Ensure all gaskets relative to the turbo, manifold and O2 are sealed tight
6. Try dialing the boost controller higher or lower and see if it has an effect

Boost leaks are always the first place to start.

Let us know what you find,

Andy

 

[siceclipse]

i bet he has the 34mm flapper...

 

[andymoraitis]

i bet he has the 34mm flapper...

It's possible, but 20 psi isn't considered high boost on that turbo and it should hold that without a problem. The 34mm should be a bit of an issue above 24 or so. Maybe the flapper's crap or the wastegate actuator is too soft. I'd just put three shim washers in it and call it a day.

 

[siceclipse]

ditto

 

[u12run]

Isn't this normal I have sat in a car that hold boost solid to redline yet.

 

[andymoraitis]

Externally gated turbo are the best at holding boost to redline. On my 50 trim I get exactly the same boost in every gear, every time. The only thing that changes this is air density and air charge temps. Nevertheless, it's always the same. Internal gates are a bit more finicky although my 16G held 26 psi to redline before I added cams and it was internally gated (but shimmed). Small turbos at high boost or small turbos on larger displacement motors will also see some boost falloff. The 16G wouldn't hold more than 20 psi to redline on my 2.3 and that was with the flapper sealed shut. That's not the case for our original poster. His boost falloff is likely related to boost leaks, flapper or wastegate issues.

 

[chanley talon]

I had this exact same problem i had a pin hole in my intercooler. MY TROTTLE BODY WAS LEAKING MY EGR AND MY FREAGIN INJECTORS WERE LEAKING BOOST. When i preformed a boost leak test this what i found>

 

[negativezero27]

i just got my car tuned today and my evoIII hits 21 and then drops to 19 around redline.

 

[vsalas793]

thanks guys, i currently hold 22 psi and spins like crazy on pump gas 93 octane. thanks for the help. i just adjusted the boost controller. and it worked

 

[GSTBlack95]

I know it sounds crazy, but what about the BOV? That could be leaky as well? My evo16g holds up 20 psi without any troubles.

 

[siceclipse]

if you have an EvoIII or any 16G WITHOUT a 34mm flapper, there is no reason it shouldnt hold 20-25 psi.