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2005 XT
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Discussion Starter #1
05 fxt VF39 with supporting mods

Was cruising from LA to Seattle two days ago.

decided to try out the top speed. hit 135 and all te sudden it felt like it topped out and i let off the gas. The car then shut off. I turned it back on while still rolling and found every time the turbo tried too boost it would shake and nt accelerate.

I pulled off the freeway and the car idled very wierd and shut off again. It seemed to run very rich and the idle was plunging up and down.

It all looked like a blown turbo. It ran terrible and would shut off every time i let all the way off the gas.

I tried reflashing the ECU back to stock the next day and i was able to drive it as long as it wasnt trying to boost. The boost gauge would just get more negative every time it tried to boost.

Then two days afer the mishap it runs much better. The boost gauge will get to about 4 or 5 and then shudder again. but it idles great and runs great besides when its trying to boost.

Please help.
 

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2016 Outback and WRX CVT
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2,589 Posts
I honestly don't know where to start.....

I want to tackle this "backwards," chronologically -

Then two days afer the mishap it runs much better. The boost gauge will get to about 4 or 5 and then shudder again. but it idles great and runs great besides when its trying to boost.
This sounds like the car's in limp-home mode (i.e. IAM low enough that it's pulled down boost) - either that, or there's a mechanical wastegate or ECU-related boost-control issues.

I tried reflashing the ECU back to stock the next day and i was able to drive it as long as it wasnt trying to boost. The boost gauge would just get more negative every time it tried to boost.
^ The boost gauge was going to vac, when you tried to boost?

Trace the line where you tapped in the boost gauge, did it partially blow-off?

I pulled off the freeway and the car idled very wierd and shut off again. It seemed to run very rich and the idle was plunging up and down.

It all looked like a blown turbo. It ran terrible and would shut off every time i let all the way off the gas.
This again makes me suspect that one of your lines blew-off. Under the driver's side, front (towards headlight) corner of the (factory) TMIC of the BL/BP-chassis Legacy, there's a "T" fitting on which the hoses love to blow-off at higher-than-stock (and sometimes even stock) boost levels. Many have taken to either "supergluing" or Zip-Tie'ing (my preference) these lines to the "T," to prevent such issues.

Is this also present on the Forester?

decided to try out the top speed. hit 135 and all te sudden it felt like it topped out and i let off the gas. The car then shut off. I turned it back on while still rolling and found every time the turbo tried too boost it would shake and nt accelerate.
Hitting either the "aerodynamic brick wall" or the ECU's programmed limiter/governor can feel like that - that the car, all of a sudden, just doesn't want to go any faster - but the car should not have just shut itself off...definitely a major pre-turbo leak can cause the symptoms that you're describing, but why did the car shut-off when whatever happened, happened?

Please clarify, though - did you all of a sudden lose power, or did you suddenly just run in to a point where the car did not accelerate any more, but you're still maintaining top-speed?
 

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2016 Outback and WRX CVT
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Isn't the Foz ECU limited to 130-ish? Thought I read that somewhere.
^ Unknown - I know that for the BL/BP-chassis, it's somewhere around 135 MPH, give-or-take, and is a limit set with consideration for the OEM tires. I don't have nearly the depth-of-knowledge with Foresters.... :icon_redface:

Is the speed governor just a fuel cut-off?
^ That's my understanding as well.

The car should just feel like it's going nowhere, yet it should maintain the speed it's managed to achieve - not actually lose power/speed, which is why I asked the OP for clarification.

And the fact that it plain shut-down? :huh::icon_eek: That not only surprises me and confuses me, but scares me. :confused:

To me a weird idle would have something to do with the intake track.
I agree, and that's why I jumped on that "T" junction issue as an example. To-a-person, everyone in the BL/BP community who've experienced this "weird idle after hard pull" event can be traced down to this cause (well, if they didn't somehow blow their engine, that is :wink:). But why did his idle "recover," if it is a true-mechanical fault? That's what I don't quite understand. :confused:

If, for some reason, his ECU was somehow reset by the event (why? I have no idea! and that's another point of confusion for me), why did he still start-off with no boost? Reversion of the ECU to default, after a reset, should still put his IAM at half-value, and thus still enable the vehicle to reach or attempt to reach boost target...so my first thought was that it was an actual mechanical fault - but his boost has, as with his idle, "recovered" over time (though still not at target).

I made a top-speed run, once, while my LGT was still new-ish, and after I hit the governor, I simply lifted and cruised back down. It was a gentle event.

Did the OP hit a huge bump in the road at that precise moment, and somehow cause, say, un-covered posts (given that his vehicle is VF39 w/full support, a level of modification would be expected) on his battery to arc, thus catastrophically shutting down the car? But if that caused, somehow, the ECU to reset itself, why did it impact his boost so? did his tuner/his current map simply choose to start IAM at such a low level, and allow the car to build it back up, as a fail-safe? I know of tuners who start at the default half-value, just to be safe, but I don't know of any who would drop it to a level as to put boost at wastegate...and then again, the OP described his first few attempts to get into boost as having totally failed - that he wasn't able to get above zero, period.

:confused:
 

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2007 Forester XT
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311 Posts
Does this model year have a pre-turbo cat? I have had cat failure on a different vehicle and this sounds like a prime example. Often the cats don't fail until you really run the engine hard, and if it were in front of the turbo, that would doubly so make it do goofy things as opposed to a normal downstream catalytic converter failure.
 

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The Modfather
2016 BRZ Limited - Manual 6 Speed Manual
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8,095 Posts
What year because the governor is around 112 (my 04) if I remember correctly unless you had it removed with an access port or similar tuning.
 

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2004 Forester XT Premium 4EAT
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30,106 Posts
Does this model year have a pre-turbo cat? I have had cat failure on a different vehicle and this sounds like a prime example. Often the cats don't fail until you really run the engine hard, and if it were in front of the turbo, that would doubly so make it do goofy things as opposed to a normal downstream catalytic converter failure.
Yes, the 05 XT was the last model year to have a cat in the uppipe. Could possibly be a case of turbo death by cat shrapnel.
 

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Pleiads' biggest leghumper
04's 2 FXT's.
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If you get into Wenatchee let me know.I will help you out with yoru car.If you need a place to stay if you come my way let me know also.I can hook ya up with a sweet deal at teh Holiday Inn Express here in town.


joe r
 

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Smooshed FOTY 2011
2005 Lifted 2.5 XT 5-Speed MT Dual-Range
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5,813 Posts
My friends' 07 Chevy Silverado has a governor at 93 mph......and it felt as if we hit something every time we ventured near it.
 

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2004 Forester XT Premium 4EAT
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What year because the governor is around 112 (my 04) if I remember correctly unless you had it removed with an access port or similar tuning.
129 actually... I've also heard that the governor only applies to 5MT models. 112 mph is the limit for the N/A Foresters, or at least the early models.
 

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The Modfather
2016 BRZ Limited - Manual 6 Speed Manual
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8,095 Posts
129 actually... I've also heard that the governor only applies to 5MT models. 112 mph is the limit for the N/A Foresters, or at least the early models.

I think you are right that was for my 99RS, 129 was for my 04 XT which has been removed with the AP apparently. AFAIK it turns off the fuel injectors or the spark plugs.
 

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2016 Outback and WRX CVT
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2,589 Posts
My 92 toyota 4runner shut down the one time I tried the top speed (90mph or so)
^ :crazy: To me, that's insane - shutting down when the governor/limiter has been reached. That really scares me!


----


RE: UP-cat. ingestion -

If the turbo grenades from ingesting big enough pieces of the pre-turbo cat., wouldn't she smoke like a diesel?
 

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2008 XT
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126 Posts
I've hit the 130mph or so limiter many times with no ill-effect, MT XT drives 100% afterwards. Something else is at play here. Limiter is not soft like a BMW, cuts power quite abruptly until speed is lowered.
 
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