GT2871r 61 turbo making too much boost at 6000 rpm

[iriehachi]

Hello everybody, I have a question about my gt2871 turbo.

When i get on the gas, it feels very laggy. The it starts making boost around 3700 rpm and reaches .55 to .6 bar of boost around 4000 rpm. I can hold it floored and it only reaches .6 to .7 bar all the way till 5500 rpm.

however, right at 6000 rpm, the boost jumps up past 1 bar and hits 1.2 bar. I have to let go of the gas to keep it from over boosting. I've tried changing the vacuum lines going to the actuator but it didn't help.

What could be causing this? When i first got the turbo, it was used and was missing the little "C" clip that holds the wastegate actuator arm to the wastegate door handle. I bought a C clip and put it on. Could that be my problem? could it be keeping the actuator from being able to push the wastegate door all the way?

I'll try running it with out the c clip today and see what happens?

Could my actuator be bad? I did test it last night with a tire compressor. I set the compressor to stop at 10psi and attached it to the hose going to the actuator. at 10 psi, i saw the actuator arm move and open the wastegate. Could the actuator arm not be moving far enough?

Thank you all


Modified by iriehachi at 2:00 AM 9/16/2009

[garagelu]

thats called a e clip not a c clip. And I don't know why you would think that would be your problem. It just keeps the actuator arm from popping off. And you won't be able to run without that clip. The first or second time you hit full boost, that arm will pop off.

These boost problems....is this with or without a boost controller? I would try running boost straight off the actuator. You should be able to hold around 14-16psi all the way to redline. If it doesn't I would buy a new actuator.

I know when you start upgrading cams, high boost, etc on the 2871r, you will get some boost creep up in the 7000 rpm range. This is usually due to the wastegate port being too small. It's a good idea to take a dremel to the port to enlarge it a couple mm and smooth it out.

But if you are only running low boost 14 psi, you should be able to hold that pretty consistantly to redline. It may creep .5 or 1 psi but no more than that.

[iriehachi]

thanks for the input. i'll start looking for another actuator.

[DrifterProdigy85]

I havnt come across a bad actuator on a 2871R. What your describing sounds like an exhaust leak at the manifold. Its leaking exhaust making the turbo not spool up quick enough at low rpm and the higher rpm is providing the turbo with enough exhaust pressure to finally hit full boost.

[iriehachi]

oh no, this makes sense. I just got done swapping out the turbo like 3 times. oh damn. i hope i don't have to pull the turbo off again.

I'll check to see if the 4 nuts came loose. if any of them did, i'll pull the turbo off and change the gasket.

Thank you for your input.

[iriehachi]

I listened for exhaust leak at idle but didn't hear any nor did i smell any in the engine bay. could the exhaust leak be happening only under load? When i installed the turbo, the gasket that goes between the turbo and the exhaust manifold looked good.

do you recommend that i replace this gasket?

[DrifterProdigy85]

drive the car and get everything nice and hot. then run seafoam through the vacuum system. It will cause alot of smoking and should show up wherever the leak might be. Also, test your boost in 4th gear and see what it hits. Start at 3500rpm and floor it from there. Should see around 1 Bar at or before 4000rpm.

[DrifterProdigy85]

Also i dont know what kinda manifold you have but i used to have a Megan Manifold and when it cracked, it did it in a spot that only would leak after it was super hot causing the metal to expand. After i removed the manifold, i filled it up with water and it wouldnt leak a drop while it was cold.

[iriehachi]

I still have the stock exhaust manifold. I'll do as you said today after work.

Thank you for your help

[iriehachi]

i took a video of my actuator. I "T"ed my boost gauge to the actuator and a portable tire compressor. this is the result.

http://www.youtube.com/watch?v=QHcy8sWihCs

is my actuator arm not moving far enough?

I also drove with my boost gauge "T"ed into the hot pipe vacuum source and the wastegate actuator.

my boost gauge went all the way to 1.3 bar. using my power FC i was able to let off the gas before boosting too much. with the power fc, i hit 1.25 bar. so, this means that my actuator is seeing at least 1.25 bar.

I'm going to try spinning the actuator arm 180 degrees to see if it can open the wastegate further... i'll have to wait till the turbo cools off