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After a longer drive (45 minutes on highway) my turbo is spooling but not putting power to the tires. The revs just kinda bounce there like it's hitting a limiter but it's only around 5k rpm. This then goes away once the car sits (overnight or after a couple hours) but comes back again after another highway drive. No check engine light or other dash lights are lit up.

Any ideas?

1997 Subaru WRX STI Type R

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  • It's almost like a vacuum leak but it "fixes" itself after a while. No dash lights at all.
    – user18985
    Jun 10 '16 at 22:33
  • Welcome to the site. There's a few Subaru geeks here that will probably flow to the question. Thanks for the contribution! Cheers!
    – DucatiKiller
    Jun 10 '16 at 22:56
  • Automatic or manual transmission? Two things that come to mind are a boost leak or a worn out clutch on a manual. In both cases, though, the problem 'going away' wouldn't happen. If the stock TD04 turbo has lunched, replacements are reasonably cheap, simply because a lot of Subaru drivers upgrade them.
    – PeteCon
    Jun 11 '16 at 1:59
  • Awesome thanks for the welcome. It's a manual. I am not convinced it's a boost or vacuum leak because like I said the problem goes away once the car sits for a while. It comes back once it's been driven for some time. Maybe just small enough of a leak that engine heat causes it to expand but I'm really skeptical. I don't think it would act like this. Someone also suggested spark plugs? The clutch is engaging and disengaging just fine; it's through the middle of the RPM range. Would it have that effect?
    – user18985
    Jun 11 '16 at 8:11
  • do you have access to a scantool? i'd be interested in what the intake air temp is when this happens.
    – Ben
    Jun 11 '16 at 11:22
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Too long for comment, but I suspect wastegate linkage or door not closing fully due to distortion from heat (it's really hot around there). You could try and get it hot enough to duplicate the problem, park, and attempt operate the wastegate manually with pliers or gloves... but it's tricky to get to without removing the turbo heatshield.

Also make sure the boost control solenoid is working, because if it isn't you will be limited to raw wastegate (around 7psi I think) with a 0% effective duty cycle. Which will be crappy choppy (bouncy revs) boost in the heart of the boosting range.

And get a boost gauge - easy install and you should have one anyway. That will tell you a lot. I suppose it could be a "boost leak", like a cracked inlet hose or loose intercooler connection, but the "bouncy rev limiter" symptom suggests a turbine leak more than the compressor side.

If it is the actual wastegate door, you will have to drop the downpipe to even get an inspection mirror look. And while it's rebuildable, maybe it's time for a TD05, VF24 or VF30? Because I'm certain you're rich like I am... or was...

Yes, I'm a Scooby Geek, but not the Subaru Geek. (He taught me everything I know... but I found out later he didn't teach me everything he knew...)

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