All of the sudden.....boost

[T-Flexx]

Seems like a lot of people have the opposite problem. My profile is updated what you see is what I have. This all started after installing the exhaust over the weekend. So my poor man MBC is set to only run about 9lbs of boost and my gauge has reflected that the whole time. Didn't want to run crazy boost until I have SAFC2 or something similar. Installed full 3in turbo back system. Took it out for a drive to see how it would sound. I do a pull in 2nd gear and I look down at my boost gauge it goes from 8....to 9 to 10........then it jumps to 15....then 20!!!!I instantly let off the gas and didn't do that again. It def didn't feel like 20lbs and I know the 14b can't do 20lbs with my mods.....so my question is what would cause the boost to read so high?? I thought a boost leak would cause rich condition and less boost?? Any insight would be great.

The car drove home fine after that pull, and idled just fine. I also made sure I didn't blow any hoses off. Didn't see anything upfront but it was getting dark.


Thanks for all your help.

 

[1davho]

I would guess that your wastegate stuck closed. You can unhook the link from your wastegate actuator and make sure it moves freely. If it does, blow air into the actuator and make sure it moves like it should. And do a boost leak test. If you have a leak in the hose that runs to the boost controller or the wastegate actuator, it will open late or not at all

 

[WES_393]

I do a pull in 2nd gear and I look down at my boost gauge it goes from 8....to 9 to 10........then it jumps to 15....then 20!!!!I instantly let off the gas and didn't do that again. It def didn't feel like 20lbs and I know the 14b can't do 20lbs with my mods.....so my question is what would cause the boost to read so high??

Sounds like your typical boost creep issue. Very common when installing a larger exhaust.

 

[Lazy]

This all started after installing the exhaust over the weekend.

+1 for boost creep.

I went through boost creep issues with my 16g & 3" free flowing exhaust. Some people say they can cure it with porting. I ended up switching to an external w/g set up.

Here is a link to a relevant thread.
http://www.dsmtuners.com/forums/art...oler/186525-how-cure-boost-creep-porting.html

 

[Joethefallen23]

Your wastegate cant keep up with the free flowing exhaust. It's creeping. The only remedy is either to increase backpressure by installing a cat, or giving the turbine and o2 housing a good porting around the wastegate to increase flow.

 

[T-Flexx]

Thank you for all your replies. I think you guys hit the nail on the head. I did check and my wastegate arm does move so prob is the creep. I guess my next question is I do plan to get a 16g turbo down the road. Didn't know if there was a supporting mod that would go good with a 16g down the road that would remedy this issue now?

 

[LandSpeed-DSM]

For better boost control on any MHI flanged turbo: port the wastegate hole, open the inlet towards the exhaust manifold and/or run a dumped O2 housing. Running an external gate off the O2 housing or manifold, dumped to atmosphere would would be a good idea as well, though more expensive than the above for basically the same effect.

You have dropped post-turbine pressure with your new exhaust system, and made it easier for a larger proportion of the exhaust to exit that way vs. through the wastegate. This is not a bad thing. You will have probably noticed a decrease in spool time and better response/recovery in addition to more power.

I disagree with the idea of increasing back-pressure to fix this issue, that is a band-aid and will hurt performance and efficiency.. especially if you only have an SAFC to tune with.

Doing the above items, you have changed the set up to allow the entire system to breathe better, resulting in lower EGTs, a higher knock threshold and greater whp/psi boost can only help. On pump gas this will be even more important.

I suggest looking into some fuel mods, starting with a pump re-wire and deleting the banjo fitting on the line that runs from filter to rail.

 

[T is for TURBO]

Yeah, port your exhaust housing, or go to an external wastegate.

 

[gsexxx]

When porting the flapper hole, make sure the flapper can still seal the hole when closed. In other words, make sure the diameter of the port doesn't exceed the diameter of the flapper.

 

[93AWDDSM]

my 3" TBE creeped bad to like 21lbsand fuelcut, I took off my o2 housing and ported that as well as the turbo hotside wastegate hole and it now holds 14-15lbs nicely now to redline.

 

[eDeclpse92]

I personally went with an external wastegate. It may be more money up front, but if you ever plan to go bigger, (which most of us ususally do even though we say otherwise) you wont have to worry about boost creep ever againg. I tried the porting, but it didn't help with me at least. I'm also running e85 on 20lbs so that's different than what it sounds like you are doing. Good luck!