turbo on, no power

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turbo on, no power

Post by ggwilk58 »

1993 turbo auto with 90K miles. Tranny is fine except for a soft 3rd
gear shift, engine doesn't speed up just a slow shift. Thinking of
trying the resistor higher shift pressure thing.

sort of comlicated symptoms but hear me out.

For a month now the engine seems to bog down at low RPM and medium
boost (medium acceleration, half throttle). re 2,000 to 2800 rpm with
5 inch vac to 4 lbs boost engine power seems flat. As soon as the
rev's hit 3,000 power comes on nice. When its bogging it seems to
surge slightly, apparently only noticible to me, the Subaru mechanic
I'm sure thinks I'm going nuts. I also noticed a slight hissing sound
when on boost. Mechanic said my up pipe may be leaking but I can't
hear any exhaust noise otherwise ($500 experiment I want to be sure
of). Gas milage has dropped 70+m / tank but may be from hitting it
harder now with the flat spot.

I have replaced, fuel filters, spark plugs and wires, valve timing
belt, air filter, and had a injector / engine power flush treatment.
No change.

1-What and when, triggers the fuel enrichment loop? Is it gradual or
on off?
2-The hissing sounds more like a intake leak to me but can't hear
where its coming from when buddies hit the gas with me under the hood.
3-Turbo seems to be working fine, lots of boost at low RPM and steady
at 8 to 9 PSI all the way up when I've got it to the rug.
4-Should the transmition be down shifting in this situation and if so
what triggers this, throttle position, engine vacuum / boost,
transmition torque, ?? I bought the car last Sept and didn't have the
boost guage until a couple months ago. I remember the tranny not
downshifting too easily but the engine 'had' lots of low end grunt.

Starts easily cold or hot and idles fine. I'm in Toronto and we've
been at -15F many times so far this year (too many times for me).

Any clever ideas?


Josh Colombo

turbo on, no power

Post by Josh Colombo »

Firstly I will suggest you check out our new board. There are still some people on this one, but most have moved over to the new one www.bbs.legacycentral.org

As for the resistor mod....don't play with it......I left the thing unplugged for a while, and started getting weird tranny issues.....I think a result of doing that the tranny takes forever to downshift, and is just plain pokey in certain shifts.

From what you described, it sounds like you're getting some of the wonderful subaru hesitation. There is a thread in the engine forum on the new board talking about the hesitation, and some of the various things that have fixed it.

Transmission kickdown is controlled a lot by TPS sensor & engine rpm.

Ask your questions again on the new board, and you should get some more answers.

Mark Ward_

turbo on, no power

Post by Mark Ward_ »

If you are hearing a hissing noise as well as no power, check all your vacuum lines for leaks. Vacuum leaks can can absolute havoc with the ECU and turbo...

turbo on, no power

Post by ssspoon@aol.com »

I agree with Mark Ward
hissing with low speed flat spot that goes away at higher rpm may be a loose hose. At low engine speed with higher vacuum, the engine feels the leak and you get a flat spot. As rpm increases and vacuum decreases, the leak is does not cause as much of an imbalance cause the engine is needing much more air anyway. Check that all little vacuum lines and big intake hoses are on all the way and clamped tightly.

Doesn't seem like many miles, but who knows what may have goofed your injectors. I don't trust those flushes the way I would pulling them out for an ultrasonic cleaning and test by somebody like RC Engineering near me in Torrance which is in southwest Los Angeles County.


Larry Witherspoon