Hey All,

So, a while back I did some troubleshooting and was able to track down my slow spooling 9.8 turbo to a leaking wastegate flapper. It wouldn't seal. I ended up replacing it with a 10.5 hotside.

Before I was hitting 19-20psi around 4000rpm with a Perrin MBC. Slow, but I was making the boost.

When I put the 10.5 housing in, I installed NEW stock BCS lines with pills. They are installed correctly. I'm not able to boost over 15psi.

Car is mostly stock. Apexi drop-in filter, balance shaft elim, Tomei crank scraper.

Like I said, I was making the power before with the MBC.

I sold the MBC (oops) to buy a GrimmSpeed 3-port, but I'm hesitant to install it. I don't want to mask a problem.

With the car being 99% stock, there should be no reason that I'd need a tune or anything to fix the problem.

I've done several boost leak tests, adjusted my WGA, checked my boost tables in the Tephra maps (changed them to stock values). Tried running the non-Tephra version of the map.

I know something in the system is working. When I first had it up and running I was hitting wastegate pressure. When I changed my Base WGDC tables up to 100 (stock) and my Boost Desired Engine Load numbers to stock values, I came up to 15-16psi (using #2 values).

I used new gaskets when I put everything together and torqued to spec. I can't feel/see an exhaust leak.

I haven't logged, so I don't know when I'm hitting peak (15).

I have no pending codes.

Plugs are fairly new and gapped well.

EvoScan passed the BCS test. Could it still be bad?

Any ideas are great as long as you don't tell me to run an MBC, put on a turbo-back, or have it tuned. I don't want to mask a problem that could possible drag me down later.

Turbo was rebuild while I had it apart. No shaft play, spins very freely.

I'm running an Omni 4-bar to log and have made the appropriate adjustments. I was logging before the swap and was within 1psi of my gauge. I'll check again when I get home to my laptop to make sure that didn't goof up or that the peripheries haven't changed.

Thanks,

Brady

 

So, is 19-20# the peak boost level that you are shooting for, Brady? At what engine RPM, and in what gear, are you reaching the 15#?

 

I just want the car to run like stock before I do any tuning and modding.

Most boost I can make in any gear is 15-16. It peaks there and tapers down to 14ish by redline. This is all by gauge. Not logging.

 

Do you smell fuel badly? Is it running richer than normal? Do a boost leak down test to find out. Most evo shops will charge $60-75 for one and that could tell you exactly what is going on. Most 8/9s after 60k or more miles, or just older engines have throttle shaft seals go bad and that will allow the boost to leak at a certain pressure and run rich. That will be your key give away.

 

Nope, no fuel smell.

I did another boost leak test this morning. Found zero leaks.

The PO had installed new Works seals. I already dealt with a half a dozen boost leaks before I replaced the turbine housing. Rock solid as far as leaks go.

 

Okay, so I did a log to make sure I'm not crazy.

Starting at 2500 I hit a max boost of 17psi at 3700rpm. 211 load.

 

Tell me what gear you logged in, dude....

 

When you mention in your opening post that you adjusted the WGA.....what level did you adjust WG spring pressure to?

 

3rd gear, sorry.

I believe I did 4 full turns past sliding on the pin easily. No creeping.

 

Run the gate straight off the compressor nipple and after establishing your current spring pressure level as a baseline, Increase spring pressure via incremental actuator adjustments up to your peak boost level. At that point back spring pressure off two full turns and reconnect your current boost control setup.

 

Will do! I'll update tomorrow.

 

Once you connect the gate straight to the comp hsg and establish what your current spring pressure level is, you may find as you continue adjusting (increasing) spring pressure that the actuator rod's tip bottoms out inside the turnbuckle. This is probably gonna be the case given a stock MHI actuator.

Since I am assuming a stock, high mileage, VIII WGA, it is probably quicker and easier to remove the turnbuckle's backup nut and just bottom the turnbuckle out on the actuator rod. By bottoming out I mean spin the turnbuckle down all the way clockwise until the tip of the rod bottoms out inside the internally threaded turnbuckle.

Even this level of adjustment is usually insufficient with the stock actuator. So you will probably need to cut a 1/4"(2-3 threads) off the tip of the actuator rod so as to be able to increase spring pressure much above 12-14#.

 

Are you thinking that the stock WGA is worn out?

I ask because I was able to run 19-20 with the MBC before, although I couldn't get my spool any quicker than 4k without creeping.

Would it be worth doing the old spring mod?

 

I would try another actuator if you have someone local with one you could test with. Every time i have had a boost issue where boost would be lower than normal and couldnt increase it would be a problem with the wga.

 

So, someone see if I'm right here.

I ran across town to meet a guy to borrow a BCS today. On the way home I got on the highway and was able to do some 4th gear pulls instead of 3rd. 19-20psi tapering down to 17ish. Full boost by 3500. On an 8 turbo with 10.5 hotside, that seems right on the money.

For everything being stock, was I just expecting too much boost out of 3rd gear?

I don't know. I'm reading and still finding people hitting more boost in every gear. Still a bit frustrated.