I have an EVO im working on that will not boost past .8 bar, so basically wastegate pressure, and hits that around 5500 rpms... after 5500 she backfires and sputters. Other then that she is fine.

Car has a brand new GT3076, brand new Tial 44mm external wastegate, forge MBC, the BOV is setup VTA, Brand new cosworth cams. Plugs are fairly new, injectors are seated and seem to be running right. Car has a pretty solid base flash on it. Manifold AFI, DP AFI, LICP AFI

Car has been compression checked, has been leak tested and aside from getting a solid answer about how to hook up the boost controller, everything looks to be perfect.

MBC is hooked up with the bottom nipple going to a nipple on the LICP and the side nipple going directly to the wastegate bottom nipple, the top nipple is VTA.

We think there is a leak on the exhaust manifold where it connects to the head, have a gasket on order, but im not so sure that it would cause the turbo to not spool like it is suppose to without it being a really big leak.

Do you guys have any thoughts as to what i could have missed with diagnosing the problem ? or have any ideas what else it could be.

***************EDIT*********** MORE INFO BELOW*******************************

Well, we thought we had an exhaust leak, we replaced the mani gasket... no leaks. We leak tested, no leaks. Swapped wastegates, no luck. The car is just sluggish causing the turbo to not spool until almost 6k and it is still only . 8 bar at most. I spent about an hour under the car looking for misc anything that wasnt connected, still nothing.

While logging the car, the most load she sees is 120. Its like there is something either clogging the exhaust and not allowing air to flow out or something in the intake track that is not allowing air to flow in. We get good spark, we have good fuel. The car runs perfect.... you wouldnt be able to tell there was anything wrong with the car until you tried to boost.

PLEASE HELP, any ideas welcome.

 

if you havent machined that manifold down you'll have problems like i did. Did you see where i had to machine mine down 3/8th's of an inch

 

hey man how are things...

first, this is a different car with an AFI manifold so, she is good..

second, that was the first thing i did when we were messing with the other manifold, had all the flanges milled, but remember, my manifold was not the ebay one, it was one we made.

 

I must be blind but I didn't see any mention of what manifold is being used?



Edit: damn post Ninja...

 

i added it,

Arizona Forced Induction

 

bump for some help or ideas please

 

sounds like the BOV is broken. does the turbo sound like it is trying to spool at all?

where is the vacuum line to the BOV connected to?

 

To me it seems like there are 2 possible problem areas:
1) Wastegate-- maybe not properly closing thus delaying the boost onset.
2) MBC-- letting pressure through or not working correctly.
...just off the top of my head
*Edit* I see that you have already swapped wastegate. So it leaves only one doubt--MBC

 

Do you have any logs(AFR's and Knock)?

 

the bov has been swapped out as well... it originally had the stock IX BOV installed, and we swapped it with my stock IX BOV.

The turbo is definitely trying to spool, there is no doubt, just either not spooling fast enough to make power, or as im wondering, there is something in the intake track or the exhaust track blocking the flow of air.
yes i do... i will add the log i took to this post.

i had to clip it some, file was too big, it was basically a log for 20 minutes at first

 

catless? leave the DP on and remove anything from there on back and try it out.

 

he has a hi flow cat...

maybe clogged ?

i didnt think about that until now, but i suppose it could be possible.

the exhaust sounds normal though.

 

I was on the same thing I have another thread as well before I tought it was my westgate or my turbo then I changed my intercooler pipe, changed the bov three times now I have the HKS whoever says is trash I can say the opposite no leak and holds boost great well I was running my car like that not being able to hold more then 1 bar at wot tought about the hi flow cat as well but no my problem was my plugs weren't right I have the NGK BPR8ES set at .024 and they were at .028 not big difference but it was doing bad for my car

 

As Kaonashi points out: You've got to fix the leak at the exhaust manifold flange. A preturbo exhaust leak however small in size it may be, can create serious problems.

The exhaust gases flow out of each port as pulses. When the exhaust valve closes it creates a vacuum. A preturbo exhaust leak sucks in air through the crack when the exhaust valve closes.

This is unmetered oxygen, since it never flowed past the MAF sensor. When the O2 sensor reads this "extra" oxygen it interprets it as a lean condition and thus the ECU adds fuel in an effort to correct this "false-lean" condition.

The ECU is thus tricked into over-correcting a "false-lean" condtion. The ECU thus starts to throw too much fuel at what it percieves as a lean condtion. So the load cells are thrown way off. The Ecu then pulls fuel to correct the now rich condition and as it leans it out then the engine knocks from being too lean.

It may seem like a little leak, but it throws the ECU's calculations way off. Sorry for the hokie explanation, but that's what you get late at night.

 

lol, thanks for the hokie...

exhaust leak was fixed saturday night... and car retested, no luck.... thats when i reedited the post. There is no exhaust leaks, no major vacuum leaks.... She holds 20 psi just fine. sooooo... aside from swapping out the cat, ive done just about everything suggested and everything we thought of.