Please Help! EVO 8 MR Making only 10psi boost
Please Help! EVO 8 MR Making only 10psi boost
I have a Evo 8 MR about 28k original miles. I was driving down the interstate gave it alot of throttle was making around 19lbs boost, all the sudden stock coupler at TB comes off. Re installed and never ran right. Did boost test throttle shaft seals done replaced with mil spec and again no more then 10lbs of boost. So I decided to go some upgrades thinking I had more boost leaks on stock intercooler, so I got a good used buschur street core, and my friend who is tremendous fabber makes me custom stainless piping and using a EVO 9 BOV crushed, I installed a ETS intake, and a set of GSC Stg 1 cams. We start her up go on a drive still only 10lbs at most. We take the o2 housing off look at shaft looks great spins perfect. We determine wastegate must be bad try and re adjust alittle better but no more then 11lbs or so. We tested MBC it was great, tried running without it, still no difference. I then buy a turbosmart wastegate actuator and install it. Feels better but only making still about 12 lbs. The wastegate flapper is as tight as I can get it. Is there in way that the turbo could be damaged from the coupler coming off under high boost without shows any signs of damage?? No boost leaks at all, MBC is good, waste gate brand new. Any ideas besides replacing turbo?? Please help
IF you have no boost leaks, tested by a reputable tester, not just assumed because you've replaced parts and think you could actually know without a test
then you would have to have something wrong with the ecu, or just a broken gauge or something
does your butt dyno feel 10psi? you should really know the difference between 200 and 300+ hp
my guess is either whatever gaskets you used to replace the stock one...if you even replaced it, are leaking
you're also dealing with modifying stock parts in a way that if not done right could cause this...i.e crushing the bov, where you could have potentially broken it
then you would have to have something wrong with the ecu, or just a broken gauge or something
does your butt dyno feel 10psi? you should really know the difference between 200 and 300+ hp
my guess is either whatever gaskets you used to replace the stock one...if you even replaced it, are leaking
you're also dealing with modifying stock parts in a way that if not done right could cause this...i.e crushing the bov, where you could have potentially broken it
you should be doing the boost leak test from the turbo inlet to test the whole system from the inlet to the throttle body...not sure how you are testing it. but form what you are saying to be honest sounds like your (crushed BOV) is not holding pressure or bleeding off... test your BOV..and also like stated in the prev comment are you sure that your gauge is ok? is it a manual gauge with a hard line going to it? the line/tube could be kinked. also just because the turbo spins freely does not mean that it is ok. you could have some shaft play in and out and if it is enough to hit the compressor housing and cause fin damage. happened to me once../ i dont think its the turbo... make sure you check everything else before you waste your money on new turbo that you dont need
We pressure tested from inlet before and seals just dumped air out. After he installed all new piping etc we did test again thru inlet and no leaks held a lot of pressure no leaks anywhere. Gauge is correct and its not making any power in butt dyno either. Didn't have any shaft play and couldn't see or feel fin damage. It feels very lazy almost as if wastegate stays open but arm has it seated as tight as possible.. I didn't see any damage to flapper or any weird wear. I am going to be safe and replace all vaccum lines with new ones after that I don't know what else to do. I guess turbo could be bad but I don't think it is. I will keep looking
EvoM Community Team Leader
Joined: Aug 2005
Posts: 5,690
Likes: 708
From: West Coast
I would verify the boost control. It sounds like you are making wastegate pressure. By that i mean if you hooked up the wastegate directly to the turbo outlet (removing the boost controller) you would make approx 12-14psi before the wastegate opened. Depending on the spring in the wastegate of course.
If it is the Turbosmart actuator, doesn't it come with different actuator springs? If so, did you install the stiffest spring?
Trending Topics
The turbosmart iwg-75 wastegate that I purchased came with 14psi spring I believe that you can purchase different springs as needed. I made several adjustments by turning the turnbuckle and lock nut to correctly seat wastegate flapper. Mbc was tested and is hooked up correctly. I am going to use a friends bov to see if that is the cause, part of me thinks that may actually be culprit. I will be replacing vacuum lines as well. Uego gauge will be getting installed hopefully today
The flapper is most likely lifting off the seat way early thus killing spool and limiting peak boost to 10-12#. The 10-11 PSI that you are seeing is about base spring pressure both with the stock wastegate and base pressure with your Turbosmart. The stock gate has a 14 PSI spring and your Turbosmart has a 14# spring as well.
Just because the flapper looks "correctly seated" upon your visual inspection does not convince me. I can explain to you how to correctly test wastegate spring pressure and adjust that pressure to where the flapper will stay so that you can boost over 10-12 PSI.
Last edited by sparky; Dec 2, 2012 at 05:16 PM.
We have tried everything, and changed out bov, boost tested no leaks etc. wastegate has been adjusted the maximum amount and still allow it to bolt up. I'm calling it a day and just gonna get a different turbo.
Given: 1) No boost leaks whatsoever, 2) No pre-turbo exhaust leaks, 3) a healthy turbo, 4) a properly routed and functional MBC, 5) a functional WGA, 6) a functional and flush sealing flapper valve, and finally, 5) a DV/BOV that is not lifting before peak boost, then I would suspect insufficient wastegate spring pressure.