RS3871 overboost, spike, AND creep.

[Tillis]

I have the ISIS RS3871 turbo kit sold by enjuku as a bolt-on turbo kit for the ka24de.
I installed this kit along with other supporting mods.
The car has been running with this kit on for less than a month.

The diaphragm on this internally wastegated turbo is set to open at 8psi. Mine will boost straight to 20 psi(sometimes less; like 17-18) then come back down to a steady 15, then will creep back up to 16-17 or so. I can never get a very consistent reading.

I have already tried two *claimed* to be new ISIS actuators given to me by enjuku. One upgraded and one stock. These didn't change anything.

I have an autometer boost gauge tee'd off properly as confirmed by their techs.

I pulled the down pipe off of the turbo elbow to ensure the flapper was opening properly when the actuator opens. It does.

I am not sure what to think other than the internal wastegate itself is faulty on the turbo.(?)

I've taken my car to Enjuku personally and they tried to help me with the time they had, but ultimately ended up sending me home with the new actuators which didn't work. They've offered to install an HKS one themselves but told me that if that didn't fix the issue they were going to charge me for the work.

Doesn't really seem fair. But before I make the drive and chance this, I want to be sure that is the issue. Their labor isn't cheap and its something I can do myself.

Any opinions on to why this could be happening?

[patsS14]

say goodbye to your ka if you keep running the boost that high

[rcdad123]

try using a boost source only for the waste gate from the intake manifold. and make sure the boost source is not restricted.

[s13silvia123]

boost leaks???

[Tillis]

I'm not intentionally running boost that high pats14.

@Rcdad Well I've seen the actuator open at 8psi like its suppose to. But I guess I could try that too.

@s13silvia there are no detectable boost leaks. Ran a smoke tester at 25psi

[K_style]

Where are you getting vacuum line for the WG?

[Tillis]

From the nipple on the turbo. It came pre connected when I bought it. I've tried changing the hose

[4x4le]

From the nipple on the turbo. It came pre connected when I bought it. I've tried changing the hose


Here is most of your problem.........

Not saying it will go away when you do it differently however your taking air pressure from one area. Air that is sometimes much hotter at some times and cooler other times. That is the air that is controlling your actuator.

Then your boost reading is coming from a different place, after several feet of piping, through an intercooler, and then in an intake manifold where an engine is drawing it in.

My first step would be to have the air Im taking my reading from (manifold) be the air im controlling my wastegate with. The line on the compressors, I dont like.

[milto0n]

As far as boost creep goes, I've had it on both of the cheap chinese turbos I ran. To remedy the problem, I took a dremel tool to widen the port for the wastegate. Now boost is always accurate.

[anarchyperf]

As far as boost creep goes, I've had it on both of the cheap chinese turbos I ran. To remedy the problem, I took a dremel tool to widen the port for the wastegate. Now boost is always accurate.

This is the solution for this problem but you don't necessarily need to go as far as widening the port. On some of the turbos the casting is a little rough restricting the air flow through the port. You just need to smooth out the casting around the port.

[godsmack]

Well everyone is saying good things but what is puzzling me is that it's opening properly at 8psi. I'm guessing that the OP tested this properly as it's not hard to do. If that is the case then I would try to run a hose for a different supply to the wastegate like what 4x4le said and see how that works.

[dcwake]

So I'm reviving this thread. Back from the almost dead. I am running the rs3871 have the nipple on the outlet connected to actuator t off with mbc. For first 2 months turbo ran fine climbed up to 15 and stayed put. This morning I go for a cruise and catch it spiking 25psi.

[Milspec180]

What about back pressure? What kind of exhaust are you running?

CA SR20 MILITARY LIFESTYLE

[dcwake]

3" turbo back with res nd muffler.