You have yet to answer if you are tuned or not. Where are you reading boost from? A faulty gauge can cause you to boost too high.

 

Looks like a normal mac valve, 3-port boost solenoid like the aem. if your wastegate is good i would suggest just do away with the fancy gizzmo controller and use the 3-port via ecu controlled boost. ofcourse this means you will need to get tuned. if you dont have a tuner i would suggest looking for one on this forums and up that boost to around 24psi if you are on pump.

 

With a full, stock exhaust you were experiencing boost taper. By swapping to a freer flowing TBE you relieved exhaust back pressure. Now you are experiencing boost creep whereas before you were experiencing taper. It makes sense.

The internal gate is in good mechanical condition. The wastegate spring pressure needs to be adjusted and you may have to fiddle around with your EBC some more.

Or as Andrew points out, you are really not peaking that high and depending on the octane rating of your available petrol you should be fine at 21 PSI. Hell, I run 21-22 PSI on 90 octane. Just get a good tune and you'll be set.

 

Not sure if adjusting wastegate spring would fix the boost creep? Wouldn't porting, going external OR just running higher boost like 22~23psi fix it?

Yeah I think I need to increase the maximum load after installing 255ltr fuelpump and LC1...

Just a quick question again, how hard is it to tune AFR, load, cam timing etc by myself by reading through the forums? I have Tactrix 2.0 with Evoscan and I did read through some of the stickies in terms of tuning, but I'm just wondering how fool-proof this is... like how likely is it for a newbee like myself to blow up the engine

 

I am not trying to beat a dead horse, but.....you are right. Theoretically at least boost creep is due to an inability of the wastegate(s) to bypass enough exhaust gas before it hits the turbine wheel.

So, the usual remedy is increasing wastegate valve size, or adding a second gate on an externally gated system, or porting the bypass passage on an integrally gated turbo. A lot of guys report positive results from switching from a traditional enclosed O2 housing to an O2 dump housing.

However, when you are adding a boost control device(MBC, EBC) to the overall picture then we are introducing a certain amount of the Fudge Factor, or a wild card, into the deck.

Let's say for example that you have an integrally gated turbo with the gate controlled via a MBC. I choose an MBC because that is what I am familiar with. The boost ramp of the turbo and subsequently the ability of the MBC to control the gate and thereby peak boost and boost taper will be totally different depending on whether you have a high level of waste gate spring preload or not.

Let's say that you want to control peak boost level at 20 PSI. There are two ways to do this with an MBC. Either you can set a high preload level on the WG spring at lets say 17 PSI. Thus, the waste gate spring keeps the valve on its seat until 17 PSI, once it lifts then the MBC controls only the final 3 PSI, that is from 17 PSI to 20 PSI.

The other extreme would be to set WG spring pressure with no preload, that is at base spring pressure(11 PSI). Here, the WG spring controls boost only up to 11 PSI. The MBC then must control boost from 11 PSI up until 20 PSI.

The second method gives the MBC more control over boost. But, you get a pretty lazy slow spooling boost curve with not much likelihood of taper or a spike. The first method gives much better spool up but since there is only a 3 PSI window for the gate to bleed off all the buildup bypass flow there is an increased propensity to creep or spike. This is where the porting of the bypass port can help.

Maybe I have wandered a bit off track with my example. So, to keep it more relevant... I have found that when trying to control boost spikes or creep it is best to first remove the boost control device from the equation be it MBC, EBC, or ECU/BCS control method.

If you disconnect your EBC from the equation and increase boost via the turnbuckle on the actuator rod alone then you will know the exact boost level at which boost creep initiates INDEPENDENTLY of the boost control device. The boost control device adds a Fudge Factor to the equation.

As, it is you cannot be sure whether or not, or how much your EBC is influencing your particular boost creep scenario. Unless you disconnect it and run the simple test that I outlined for you.

Controlling boost creep has to be approached in a systematic fashion. You have to have a checklist and eliminate the possible causes one by one. I see that your EBC is a possible cause to your problem. This can be verified. Another possible cause is too much or too little waste gate preload. But, you don't know how much preload your WG is actually running do you? So, you are just shooting in the dark.

There is no reason why a stock unported integral gate can't handle the bypass flow of your mildly modded engine. You don't need an external gate. You just need to sort out what you already have.

 

Thanks for your replies sparky.

So basically if I directly connect the manifold pressure vacuum hose into the internal wastegate nozzle, I should be able to tell whether the bcs or the size of the bypass hole is the issue, right? (assuming I don't suddenly boost hard at high rpm, which "could" be fixed by adjusting preload)

Some guy suggested I go for Grimmspeed BCS which is stock replacement BCS and use the stock ECU to control the boost. According to him that's the way to go and apparently he has had quite a number of boost creep issues with MS-IBC boost controllers as well.

I'll try and connect the vacuum hose directly to the internal wastegate nozzle and see if the boost still creeps.

 

If you are "T"ing into the IM-DV hose as a boost reference for your EBC, then I want you to block that off. On the compressor outlet's "J"-pipe there should be a reference nipple. Run a 4mm hose from that nipple to the nipple on the wastegate actuator canister.

Don't forget to plug off all the open hose ends when you disconnect your boost controller. You can use golf "T"s, or machine screws secured with nylon zip ties. We don't want any boost leaks.

Then remove the cotter pin that holds the turnbuckle onto the wastegate flapper valve's pivot arm. Loosen the backup nut that fixes the turnbuckle onto the end of the threaded actuator rod. Pop the turnbuckle away from the pivot arm by prying from behind with a long shafted flathead screwdriver.

Now, rotate the turnbuckle until it freely slides on and off of the pivot arm. This is your turbo's base waste gate setting. Once you have verified the base pressure by taking your car for a spin in 4th gear you can start adjusting the spring pressure in earnest.

Pop the turnbuckle away from the pivot arm again and rotate the turnbuckle in about three complete 360* rotations clockwise. Hook the actuator back up to the turbo and go for another spin in 4th. This should get spring pressure up to about 14 PSI. Is there any creep at that boost level?

Now go through the procedure another time with two more complete rotations inward this should put the boost level up around 16-17 PSI. Is there any creep? Etc.....

If we get it via this method up to 16-17 PSI w/o any creep, then we can be sure that is not a wastegate flapper valve, or an actuator problem. So, we can then look closer at your EBC as a contributing cause.[/COLOR]