Boosting Problems...

[j0hn6oo]

I've been tearing my car apart looking for a fix to this problem for 3 weeks. When the car reaches 20 PSI or so, it all of the sudden drops down to around 7 PSI and holds there until I release the throttle and do it again. It seems to do this at around 3800 RPM regardless of boost or gear. I have SEALED the BOV and tightened the wastegate actuator down so much that it doesnt move at all so it cant open, and removed the MBC. There is nowhere else it can leak. It's leaking before the GM MAS because the WB still reads right.

Any help is GREATLY appreciated, thanks.

 

[cruisintalonawd]

Do a boost leak test

 

[brian9397gsx]

have you tried to actually do a boost leak test? thats where i would start first, im sure im not gonna be the only person telling you this

 

[jag987]

I've been tearing my car apart looking for a fix to this problem for 3 weeks. When the car reaches 20 PSI or so, it all of the sudden drops down to around 7 PSI and holds there until I release the throttle and do it again. It seems to do this at around 3800 RPM regardless of boost or gear. I have SEALED the BOV and tightened the wastegate actuator down so much that it doesnt move at all so it cant open, and removed the MBC. There is nowhere else it can leak. It's leaking before the GM MAS because the WB still reads right.

Any help is GREATLY appreciated, thanks.

So you've "sealed" the bov
and basicly disabled the wastegate

fists off I think your crazzy (for the above), but thats just me.

but,
I am assumeing that you are reading your afrs in dsmlink, or something like that, to compare them to your wideband, otherwise that would mean nothing. I would still do a boost leak test, because I don't like to think about what else could cause this.

Sounds like the turbo is giving up, or maybee the wastgate is blowing open, but you said it can't open. It would be good to have a way to verify that the wastegate is not opening at the 7 psi.

 

[j0hn6oo]

OK, I will do a boost leak test tomorrow.

fists off I think your crazzy (for the above), but thats just me.

Believe me, I couldn't think of any other way to verify that the wastgate would stay closed. And the BOV is no big deal if it's sealed for 1 or 2 pulls.

 

[j0hn6oo]

OK, I did the boost leak test and it holds 30 PSI no problem. It must have something to do with the wastegate. My O2 housing is missing a couple bolts because they sheared off in my old turbo, but I wouldn't think that would be that big of a problem. Any ideas???

 

[stefanOst]

Sound like the flapper could be blowing open

 

[j0hn6oo]

Whats the best way to fix this, upgrade the actuator or switch to an external?

 

[j0hn6oo]

Sorry for the double post but do you think this could be caused by too much backpressure? I have the stock exhaust back to the cat and it was broken so I did a quick fix to it and now it's a little smaller.