Boost drop with V3 BCS - Evo316g

[tsitalon1]

ey guys,

Need a little help diagnosing a boost drop off issue.

Target boost 20-21psi

Mods:
stock manifold
stock o2 housing
3" DP with 2.5" o2 flange
Mil spec 3" racing metal cat
3" catback with no-name performance muffler
IR 3 port BCS
3" K&N open element AF
Crushed BOV (not audibly leaking at 25psi)

Symptoms:
boost spikes to 21 around 4k and drops to 17-18 by 7k

EcmLink WGS tables >90% from 5k - 7k.

Things I've tried:
Found two boost leaks after Evo FMIC install - fixed
Slight (very slight) shim of the evo316g WG actuator (one lock washer on each side)

BCS installed so that boost pressure passes through BCS until BCS is activated.

Can't decide if this is classic WG being blown open or something else. Do Evo316g WG's blow open at ~20psi?

Any other thoughts?

 

[ktmrider]

Does taper boost stay the same even if you raise target boost?

Just a few things that caught my eye: stock EM and O2, EVO intercooler, e16g.

In combination you may be out of flow capability. IC runs out quick on EVO's, heard 300whp or so.

 

[Barnes]

He *should* be able to generate more than 17psi after 4k. I don't think he's hitting a flow limit. I think something is wrong. (For example, with my E3-16g that is boost creeping, I can *easily* go past 20psi with STOCK IC piping and intercooler up to redline. /ubbthreads/images/graemlins/ooo.gif)

Where is your boost gauge tapped in? Are you *sure* the boost gauge is accurate?

I'd then do another boost leak check just to be sure. Then make sure you exhaust manifold is not leaking between the cylinder head, or at the connection to the turbo exhaust housing. (I.E. pre-turbo exhaust leaks)

If you are willing to live dangerously, and exercise caution, you could simply pull the vac line to the wastegate actuator. Then gently bring the car up to the rpm/load level that generally won't let you hit the boost you want. Then roll into full throttle and watch the boost. If you get the same results, you can atleast discount an electronic control issue, i.e. the BCS & DSMlink. Either the WG is blowing open, or some other mechanical issue is at play.

After that point I'd double check to make sure the wastegate actuators internal spring is still strong. (No reason to believe it wouldn't be, but it's easy to check.

Then, if you *really* wanna live dangerously, remove the wastegate actuator completely, and wire the wastegate flapper shut with safety wire or some other means. /ubbthreads/images/graemlins/ooo.gif Then you'd know for sure your turbo is simply not generating enough pressure. Although this would be a last resort in my opinion.

At that point it would have to be pre-turbo leaks, boost leaks, or something is block/restricted making that boost level impossible.

 

[prove_it]

How did you set-up your boost control? Did you dial in your targets then click the button to allow the ecm to adjust and target the desired boost? Are you running an inline boost pill? Did this all happen before using the boost control in link?

 

[tsitalon1]

Quoting Barnes:

Where is your boost gauge tapped in? Are you *sure* the boost gauge is accurate?



Boost gauge tee's off the BOV line. Problem started after Evo 8 FMIC install. Maybe because I'm using stock IC hoses and reduction elbows to connect the FMIC to the stock IC hoses?

Quoting Barnes:

I'd then do another boost leak check just to be sure. Then make sure you exhaust manifold is not leaking between the cylinder head, or at the connection to the turbo exhaust housing. (I.E. pre-turbo exhaust leaks)



I'll triple check for boost leaks and will look for pre-turbo exhaust leaks as well.

Quoting Barnes:

If you are willing to live dangerously, and exercise caution, you could simply pull the vac line to the wastegate actuator. Then gently bring the car up to the rpm/load level that generally won't let you hit the boost you want. Then roll into full throttle and watch the boost. If you get the same results, you can atleast discount an electronic control issue, i.e. the BCS & DSMlink. Either the WG is blowing open, or some other mechanical issue is at play.

After that point I'd double check to make sure the wastegate actuators internal spring is still strong. (No reason to believe it wouldn't be, but it's easy to check.

Then, if you *really* wanna live dangerously, remove the wastegate actuator completely, and wire the wastegate flapper shut with safety wire or some other means. /ubbthreads/images/graemlins/ooo.gif Then you'd know for sure your turbo is simply not generating enough pressure. Although this would be a last resort in my opinion.

At that point it would have to be pre-turbo leaks, boost leaks, or something is block/restricted making that boost level impossible.



I switched to a MBC for testing and I have the same symptoms - Can get well over 20psi up to about ~5k, then drops to about 18 by 7k.

I'm thinking maybe I should preload it with 3 washers on each side and maybe it'll hold 20+psi at 7k. Then just use DsmLink and the BCS to control the spike that will inevitably be produced.

I'm also looking at getting an Evo III o2 housing as it might help the exaust side flow more.

 

[tsitalon1]

Quoting prove_it:
How did you set-up your boost control? Did you dial in your targets then click the button to allow the ecm to adjust and target the desired boost? Are you running an inline boost pill? Did this all happen before using the boost control in link?



Not using EC at all in Dsmlink.

Installed a boost pill after the issue started to see if it would help - no difference.

Nope - issue started around the time of the Evo 8 FMIC install. Used stock IC pipes/hoses all the way to the IC, then used reducers.

 

[MellowVR4]

had this same exact problem on mine, fixed is with putting 3 washers on each side of the wg actuator bracket. Held the boost all the way to redline.

 

[tsitalon1]

Mellow - where did you source your Turbo from? FP/MAP/or Extreme PSI?

I read the ExtremePsi ones had longer rods requiring more washers.

As mine sits now (one washer) I have half of a hole preload. Meaning the actuator has to be extended about a 1/4 inch or so to place it on the wastegate flapper arm.

 

[prove_it]

You can also buy a thread die and two lock washers and a sleeve and make the actuator arm adjustable too. I did this on one before to make it easier to install without the washers.

 

[MellowVR4]

Quoting tsitalon1:
Mellow - where did you source your Turbo from? FP/MAP/or Extreme PSI?

I read the ExtremePsi ones had longer rods requiring more washers.

As mine sits now (one washer) I have half of a hole preload. Meaning the actuator has to be extended about a 1/4 inch or so to place it on the wastegate flapper arm.



I got mine from a local guy, brand new, i doubt when he bought it was from any of those sites.

 

[MellowVR4]

But that was my problem, once the rpm's got to about 5k-6k the boost went from 21psi to 17psi everytime. I would put more washers on if i where you.

 

[Barnes]

So before the evo8 FMIC, you could hit the boost you want? And the only thing you changed was to replace the stock IC with the EVO8 fmic?

 

[tsitalon1]

Kind of...

Was targeting slightly lower boost levels with the Gvr4 FMIC.

Raised boost with the Evo 8 FMIC.

Also I'm not so certain I was monitoring high rpm's as much in the past.

 

[prove_it]

So this could be a problem from before that you never noticed?

 

[tsitalon1]

Could be, I plan on reshimming the actuator with 3 washers as Mellow suggested and see what happens.

 

[tsitalon1]

hey guys, I've added the three shims, checked for exhaust leaks, changed the boost controller's boost reference to the blow off valve line.

still no change really, I can spike well above 25psi but fall to 18-19psi at redline.

I'm suspecting that my generic performance muffler may be the culprit. I'm planning on removing my exhaust from the down pipe and seeing what happens.

Any other ideas?

 

[tsitalon1]

Will try removing the exhaust from downpipe back this weekend.

Do you guys have any other ideas?

 

[Lukefraizer]

I had the same issue with 619, what was happening with mine was the spring in the boost controller was weak and allowed the boost to creep off. Replaced the spring and the issue is gone now.

Luke

 

[tsitalon1]

I'll keep this in mind - Though I can tell you with it shimmed with 3 washers the spring tension seems very high.

 

[Barnes]

Is your manifold tapped for an EGT?