No boost - troubleshooting order

[billjr212]

Okay, so at the end of my session of hpde a couple weeks ago, I suddenly lost boost pressure. Looking for a good order of troubleshooting. The threads on nasioc all seem to jump around with a bunch of self proclaimed experts, so hoping to keep things a little more step by step here.

I'm not building any boost, it's not simply leaking by as a result of loose intercooler hoses or similar (I've had that on a previous wrx, and it is a very tell tale sound)

Peaking at about -0.2 psi, so essentially nothing. The eclip on the wastegate arm appears to be in place. The wastegate is opening and closing with a strong grip and a good pull. The hoses back to the intake appear to be in place and no obvious leaks. Went ahead and reset the ecu using the accessport, but no change.

At this point, my mind is going to oil build up in the turbo/intake (or oil starvation, I suppose) followed by "pop" so to speak during the high g force cornering, meaning I need to swap out the turbo.

The question, then, is: are there any more diagnostics I should do first before I start pulling things apart?

I have a spare turbo, but no idea if it is any good.

[Wayne Presley]

I'd bypass the BCS and see if you have any boost. Also check that the WG flap valve is actually closing,

[redfogo]

Check shaft play on the turbo and do a boost leak test with an air compressor.

[Ironhydroxide]

Check turbo shaft play by pulling the downpipe and grabbing the exhaust wheel with your fingers. It should spin smoothly and easily with very little up/down/side/side movement and zero noticeable in/out movement. If there is movement or it doesn't spin smoothly, time to replace.

[tmoretta]

I drove my turbo 818 for the first time yesterday. I also had no boost. When I had the engine tuned it was developing 18 psi. the only thing I have done since is added a Supertrap Muffler with a minimum of baffles for maximum sound attenuation. I am wondering if I have so much muffling it is not allowing the exhaust to flow fast enough.

[billjr212]

Thanks guys. Turbo is shot. Pulled the intercooler and downpipe. Oil in both intake and exhaust sides. Turbine wheel very loose and shows in/out movement. Luckily I have an extra turbo. Just need to hope no wider engine damage and fix any underlying problem before my next track day (which won't be until next summer).

[longislandwrx]

What year size engine... do you have oil screens in there?

[billjr212]

What year size engine... do you have oil screens in there?

Is that directed at me or tmoretta? Mine is a 2004 2.0. I'm going to go with "no" because I don't understand the question.

[Wayne Presley]

In the banjo bolt Subaru put screens that sometimes get clogged and no oil goes to the turbo...

[billjr212]

In the banjo bolt Subaru put screens that sometimes get clogged and no oil goes to the turbo...

Oh, that's fun. Learn something new every day. I'll keep an eye out for this when I go to install the replacement turbo. I got it pulled off the donor motor (which was dead due to bent valves) last night and planning to pull off the dead turbo tonight and finish up the swap. Then I'll probably rebuild the dead turbo and add it to the list of "things I've learned" as well so I still have a backup.

[STiPWRD]

Debris in the oil can kill your turbo's bearings so I'm running an in-line serviceable filter:
http://www.forcedperformance.net/PROD/FP4ANFilter.html
If you clean it every time you do an oil change, it will prevent contaminants from damaging your turbo. I didn't know subaru put screens in some of their banjo fittings though.

[billjr212]

Finished swapping the turbo out last night around 1 am. Took the attached terrible picture. Damage is obvious (if the picture weren't so blurry), but points to the first person who sees the underlying problem. (read the fine print if you can)

[billjr212]

Geez - that picture really is miserable. Anyway, it is a TF035 turbo. It was on the EJ205 motor I purchased from JDM Motors that supposedly came out of a JDM WRX. I have to do a little more research, but seems these were only used on Foresters and intended for around 10-12 pounds of boost, meaning my Cobb Stage 1 tune would have destroyed it. Never thought to look closer at the turbo for a model number when I bought the motor (I checked for shaft play and it was good at the time of installation), but I guess add it to the pile of lessons learned. The swap to the TD04L was easy enough except the oil supply line is slightly different and had minor clearance difficulty.

For the record, if FFR had moved the shock tower support brace an inch back and a half inch up, this would have been the world's easiest turbo swap. With the brace in place, it was basically the world's most frustrating game of tetris.

[Wayne Presley]

For the record, if FFR had moved the shock tower support brace an inch back and a half inch up, this would have been the world's easiest turbo swap. With the brace in place, it was basically the world's most frustrating game of tetris.

Now that's funny!

[CNC_Geek]

Looks like I just learned something new also. Have not fired off my twin turbo JDM engine yet however I have found oil in the intercooler and the turbine on that side has much side play. And I thought I was getting tires next month.

[STiPWRD]

Looks like I just learned something new also. Have not fired off my twin turbo JDM engine yet however I have found oil in the intercooler and the turbine on that side has much side play. And I thought I was getting tires next month.

The turbo inlet pipe sucks in oil vapor by design so it's normal to find oil in the intercooler, unless there was an oil catch can. Oil in the turbine side and side play are another story, you may want to look into that. I ended up replacing the bearings in my used 18g.

[Sgt.Gator]

There was a Subaru TSB on replacing the turbo banjo bolt screen with every oil change. Everyone I know just takes the screen out. Here's info on the Subaru Turbo Banjo Bolt:
http://www.forcedperformance.net/mer...Info_SubaruOil

The linked FP inline filter (above) is also a good idea if you remember to clean it all the time.

[305mouse]

Never heard of a tf 35, I had a VF35 on my Saabaru. Had no problem holding 24 psi with an EWG. Problem is its smaller, great for spool, bad for top end.

[AJW Performance]

Never heard of a tf 35, I had a VF35 on my Saabaru. Had no problem holding 24 psi with an EWG. Problem is its smaller, great for spool, bad for top end.

I am also not familiar with a TF35 turbo, you learn something new everyday though.Google tells me that's a standard UK Forester Turbo. Interesting!