ok here is the deal. im starting to tune on meth. i cant get the car to boost past 25 25.5 psi. normaly i run spike 24 psi and tapper to 22 ish psi at redline on 93 oct. now im adding meth in and i turn'd my forge mbc up about 15 clicks from my normal setting. started to do my pulls and 24 25 psi. so my tuner said to pull the waste gate line and see if it spikes higher. if so i have a boost leak he said. so i pulled the line and again. 25psi. brought the car home and did a boost leak test. 32psi it help strong. 4 times till i blew my tester apart. so i put everything back togeather and tested my gauge. dead on. went and did more pulls and again 25 psi. so now i just turnd the mbc all the way up and still 25psi. wtf


i used to run 100oct. and when i did i was able to get 27 28 spike psi. now i cant even get past 25 psi on meth. any one help me???

boost gauge is dead on.
did a boost leak test
car runs perfect
pulls hard
not knocking
spools up fast

 

do you have the heavy spring in?

 

yes the heavy spring is in. and i have a forge waste gate.

 

do you have the stock BOV?

 

no i do not. and like i said i did a boost leak test to 32psi and it held for a long time. so my bov is not leaking. nothing it leaking

 

???? anyone?

 

Could it be the cooling effect of the meth causing the charge to condense and drop pressure?

Race gas wouldn't do that because it's injected at the injectors where as meth is injected way earlier and actually has a chance to cool the charge.

 

i have no idea as im a newbie to meth injec. my intake temps befor the meth jet are around 88deg. my meth is set start 7 max 22. the mbc is all the way up. spike 3rd gear 25 psi. 4th i might tap 26. more like 25.8

mwth kit is a cooling mist with veri cool and pda

 

you mean turn the mbc all the way down right? as in screwed in not out?
i think you just cant adjust it right. it happens. take it out make sure when you turn it it compresses the spring.

 

up down in out. lol there is a + and - on the knob i turn'd it +. i guess the spring would be pushed down for more pressure befor it opens. so yea your right. i just stated myself wrong but ment the same thing. its all the way to the + side on the heavy spring.

 

i dont know. i went back out and pulled the waste gate line again. peak boost 3rd gear starting from 2600rpm to 7100 rpm is 26.1 psi.

did another boost leak test 35 psi. held for a long time. i even did this 1 with and 1 without the throttle body open. no leaks. nothing.

i should of bought this damn car in red.

 

Have you tightened down your actuator rod on your wastegate yet?

 

I don't think it matters right now. I think its fine. On pump gas I run spike 24psi on 100oct I was running 27.5 spike. So I think the actuator is fine. This problem I'm having just started when I was tuning for meth.

 

Maybe your mbc went bad? My forge sure did. Wouldn't hurt to try a buddie's mbc.

 

You might wanna get an idea of just how much preload you are running on the WG since it won't cost you anything and just takes a minute to try.

The easiest way is to just to turn your MBC out , counterclockwise, all the way to fully soft(as far as it goes), and take it for a WOT run.