Hello I have an 03 Evo 8 with just an AEM intake, and a Hallman MBC set to 20psi. When the car goes into boost at about 3000-3500 rpm the car will boost about 19-20psi and stay like that till about 5000rpm then jump to 22-23psi. Then once it does that it will start falling back to 19-20psi to redline.....Any thoughts?

Could it be my stock BOV leaking?

 

if its really cold out around you, it might be the cold weather.

 

Either way the boost is fluctuating a lot!!

 

It is about 13* out right now.....but how would that explain the major fluctuation? I have had an SRT before and it never did this with a Hallman on it? Maybe I should try getting an electronic boost controller?

 

I really don't think a EBC is going to help that situation.

I also have a MBC and on this cold cold weather, boost does spike higher than usual but it comes back down.

 

told you it could be the weather, plus a few other mods.

i have n EBC and mine does this on my gt35r.. so i wouldnt worry TO much about it

 

Do you have a test pipe?

 

It's normal in my experiance just turn it down till it warms up a little.

 

I have no test pipe....just an AEM intake and a MBC..

Thanks for all your help gentleman!

 

when i had my evo 8 with the plastic bov it happened to me with the hallman mbc. So i switched to a greddy type s and it held boost fine.

 

is yours a mechanical boost gauge? Sometimes the gears in them "stick"

 

Well do a boost leak down check and see where you are leaking boost. If you have a stock bov upgrade to something like a forge which will hold over 30 psi. But definetly do a boost leak check. Friends car had the same issues on the dyno and we had already done a boost leak down check and the throttle body shaft seals were bad. Anyways thats my 2 cents It is a boost leak or your bov just cant hold boost. Peace.

 

I had the same issue last night, I installed my boost gauge then took the car for a ride and saw it going up as high as 24 at WOT. 3k miles on the car and My only mods are hks hi power catback and dc downpipe with cat delete BUT it was like 10 degrees outside. I hope it was the cold weather causing the boost to go so high. the vac sits perfectly at -20.

 

I'll do a leak check....thanks man!

If my TB shaft seals ARE bad...how do I fix this?

 

I just had a similar issue with my Hallman MBC.

Take the MBC apart and clean all the old assembly lube out of it. Reassemble all the parts with silicone grease (same as brake grease) and you'll be fine. I found that the Hallman was sticking and this cleanup did the trick.

Don't forget that in this cold weather turbo cars will spike more often than in "normal" weather, but I think your Hallman is the culprit on this one.

Darin