br1ev8

After installing a TurboXS MBC on the 18g Greddy kit and setting the boost to ~10psi, the boost will not hold. Boost will rise to the 10psi that we have the MBC set for, then it just drops back down to about 7.8psi, where the internal wastegate spring is set at. Any reasons why this could be? It seems pointless to have a boost controller if I can only realize increased boost during a short spike.

Autoworks

did you put the MBC in backwards?

br1ev8

hehe, no, its correct.

boostedcivicsir

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Autoworks &raquo;</TD></TR><TR><TD CLASS="quote">did you put the MBC in backwards?</TD></TR></TABLE>

my thoughts exactly. it will only let you boost to the wastegate setting if thats the case.

for ***** and giggles, make sure t isnt.

Jay_Sensing

Did you start turning the BC out yet or is this where it went still screwed all the way in? I used a couple of TXS MBC's and they all had a 2 to 3 lb spike and then would settle at what they were suppose to be set at.

I switched to turbosmart and it worked like a champ and I have used them on both Hondas and DSM's and had the same problem with TXS.

nfn15037

The spring is too soft in the wastegate actuator and the flapper is being blown open by exhaust manifold pressure. Add more springrate somehow. You can remove the vacume line and it still will only spike to 14 PSI or so and fall back down to 10-12.

tannerLSt

same thing happened with my 18g kit....same boost controller....

Integra21

i have a blitz sbc-id (ebc) and it seems to hold nicely but does fall a psi or two near redline

br1ev8

So pretty much an mbc is useless unless I can figure a way to increase the wastegate spring tension? Any ideas on how to increase the tension by only like 2.5lbs? Or, I guess my only other option would be to weld/permanently seal off the internal wastegate and get another manifold and external wastegate.

92gsrteg

hmmm i have the 18g turbo on my jdm gsr and i set my boost at like 10psi and it goes to 10 then drops to only like 9 and holds all the way to 8,500 rpm's. I also adjusted the wastegate actuator arm really tight so that when u pull it open(simulating the waistgate opening the flapper), the flapper itself will only open a little teeny bit. What this does is put a lot of force on keeping the flapper closed til desired boost is reached, i was worried that it would boost creep on high rpm's cause of this but its fine. so just play with the actuator arm, making it shorter and shorter until u barely get any spike. hope this helps good luck

Spec R

i havent pushed passed 8.5 psi on my 18G with my Dawesdevices MBC, but i havent seen any spiking issues at all with it, but the needle does fluctuate/vibrate over half a psi at a crazy rate once i reach the target boost. but then again, i'm not using the stock greddy wastegate actuator.

Blk93Sihatch

anyone know what is the highes boost the 18g can handle. I heard 15 psi with the stock internal wasgate and a boost controller.