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2005 Subaru Outback 2.5i Base, Pearl White
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128 Posts
Discussion Starter · #1 ·
2005 Subaru Outback 2.5i 4eat.

So the car just tried to kill me. I was checking the tire pressure *at the gas station and I went to turn the car on and it was idling really high at 1500 rpm even though it was hot. Put it into drive and it lurched forward. Driving down the street with the foot off the accelerator it was powering forward accelerating. I pulled into my driveway and with the foot on the brake it was accelerating hard forward barely slowing, I pulled the e brake giving me just enough time to shut it off before it could jump the rocks. I tried turning it back on a few min later and it accelerated to redline before I shut it off.

Anyone following my other thread knew I suspected the TPS for my knock issues. Is this the TPS telling the car I've got my foot in the gas when I don't?

Time to rename it Christine?
 

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2001 VDC Wagon - White pearl - 302,000 km
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466 Posts
Correct me if I'm wrong, but I believe the 3rd gen OB uses a drive-by-wire, so it's most likely a faulty throttle servo, unless your throttle sensor on the gas pedal 'is' giving it an erroneous signal.. Pop the intake snorkel off and see if the throttle plate is stuck partially open. Cycle the key a few times without starting it and see if the throttle plate moves. Try slowly stepping on the pedal with the key in run to see if it responds.
 

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Any trouble codes? (Your BtSSM should be able to read them -- Key On but engine Off.)

Failsafe when there's a throttle control problem (and yes, it is drive-by-wire) is to hold rpm at around 1500 rpm. But the acceleration to redline is puzzling. What does BtSSM show for the Accelerator and Throttle positions (%) with the key at ON but engine not started? And when the pedal is pressed down slowly, do both advance?
 

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2005 Subaru Outback 2.5i Base, Pearl White
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128 Posts
Discussion Starter · #6 ·
There's no trouble codes at all.

I've been following this weird no sound "knock" issue that shows up on my BTSSM . I have this low o2 sensor voltage at idle when the car is fully warmed up. I've replaced everything and checked all fuses and relays associated with o2/AF sensors and replaced MAP, MAF, done top engine throttle body and fuel injector cleaners. Air filter, spark plugs, wire, coils everything is fine.

I think the throttle body is letting too much air in intermittently. I live upon a mountain at 5,500 feet and the car was running great when I went back to 87 Shell, held an IAM value of .80 for weeks. As soon as I went to the desert at sea level it pulled timing all the way back. When I got back up the hill the timing went back up to .50 and then when I went back down to the other side of the mountain at 2000 feet it dropped but not as severely.

When I shut the car down I noticed on btssm the throttle plate % cycles erratically before stopping at +/-7%. Sometimes at idle it's fine, 1-2%, sometimes not. Sometimes with the engine off it's 7%. There's a discrepancy between pedal position and throttle position as well.
 

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2017 2.5 Outback Limited no Eyesight
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130 Posts
This is an obvious first question, but I have to ask. You've checked that the front drivers floor mat to be sure it hasn't moved forward to affect the throttle pedal. This DID happen to me. It's the simplest to check prior to other testing.

Edited to add:
We were posting at the same time and I've now seen your latest posts...
 

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Master Caster
🖤💔💙 3 Beautiful OBXTs
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16,322 Posts
There's a discrepancy between pedal position and throttle position as well.
There always is.

The OEM Map will render the TP 15-20% less than the accelerator. One of the main changes with performance tuning is to reverse that. Or align both into closer proximity...so it seems more linear...
 

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2005 Subaru Outback 2.5i Base, Pearl White
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128 Posts
Discussion Starter · #10 ·
Oh god I'm so f&@!in stupid.... DMac wins, my weather tech floor mat was hooked on the underside of the pedal. Didn't totally fix it....

Still my throttle plate is hovering between 6-7% and throttle pedal is at 6-7% with nothing depressing rhe pedal?
 

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'98-2.5L & '05-3.0L Subaru Outback Wagons
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142 Posts
OK, floor mat.

However, had a similar problem with a 90's Chevy (5.7L V8). It was a vacuum leak. OBD wanted to maintain clean "stoichiometric" emissions. So a vacuum leak allows more air into the intake stream. Result, the ECM (Engine Control Module) added fuel to keep the emissions correct (O2 sensor). Adding fuel = faster idle, dangerously faster in this case.

Trig
 

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Master Caster
🖤💔💙 3 Beautiful OBXTs
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Oh god I'm so f&@!in stupid.... DMac wins, my weather tech floor mat was hooked on the underside of the pedal. Didn't totally fix it....

Still my throttle plate is hovering between 6-7% and throttle pedal is at 6-7% with nothing depressing rhe pedal?
Floor Mat...lol.
 

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2005 Subaru Outback 2.5i Base, Pearl White
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128 Posts
Discussion Starter · #13 ·
In my defense I've put in 12hrs a day for the last week. *cough *stop judging me.

Hey look guys something is still broke on the car. *smashes something *
 

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Master Caster
🖤💔💙 3 Beautiful OBXTs
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stop judging me.
Definitely NO judgement from Me, just laughter. This is from the guy that dropped washer in cyl #2 and admitted it...after Said #2 bashed into small bits...but still would not start...

:confused: :ucrazy: :cursin:

yeah...that's me....
 

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The photos are KOEO. The DBW throttle is activated, but if the accelerator pedal is released, the accelerator pedal position ("throttle pedal") should read zero. If it's showing 6-7%, either BtSSM is reading the wrong parameter, or the pedal is faulty. There's a long thread here on problematic earlier version 3rd gen pedals: http://www.subaruoutback.org/forums...4906-code-p2138-throttle-position-sensor.html

When the engine is turned off after running, the ECU will cycle the throttle plate through a swing, and then it settles down to its rest position. The ECU remains active for about a minute after the engine is turned off, so the relationship between the accelerator pedal and the throttle plate is still active. You can press down on the accelerator and watch both it and the throttle plate move. As was noted, the two do not necessarily correspond, but will move similarly except when the accelerator pedal is pressed down beyond about 30% at which point the throttle plate might move up to 100%. This is normal.

On my 07, KOEO, with the accelerator pedal position at 0%, the throttle plate is around 12%.
 

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On the Super Mod Squad
2002 3.0 VDC Wag + 2018 2.5 Leg Ltd
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27,171 Posts
In my defense I've put in 12hrs a day for the last week. *cough *stop judging me.

Hey look guys something is still broke on the car. *smashes something *
and if you wore white or light colors while in the brain boiling sun,....this would never have happened.



I had to fix a aftermarket carpet mat in a teenager's new to him car a few weeks back,.

...power drilled a hole right through it to anchor it on the existing subaru plastic pin. .

...and I was surprised that mat hat not killed the previous owner.
(garbage thing was rolled up under / around the gas pedal.)
 

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2005 Subaru Outback 2.5i Base, Pearl White
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128 Posts
Discussion Starter · #17 ·
Well I don't feel so bad. I guess now I can get back to cleaning pine sap off the car (goo gone is the trick) and figuring out why it doesn't like going to sea level. Ha.
 

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2001 VDC Wagon - White pearl - 302,000 km
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Well I don't feel so bad. I guess now I can get back to cleaning pine sap off the car (goo gone is the trick) and figuring out why it doesn't like going to sea level. Ha.
What is Subaru's methodology of capturing barometric pressure readings. Is it a snapshot of the value at KOEO, or is it constantly monitored? Older EEC systems would take a BP reading at startup and AF ratios were based on that reading regardless of what altitude you ended up at on that drive cycle. It would explain why your car runs fine at the bottom of a mountain, and then runs like crap at the top, and vice versa.
 

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2005 Subaru Outback 2.5i Base, Pearl White
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128 Posts
Discussion Starter · #19 ·
What does KOEO stand for?

The ECU constantly monitors the barometric pressure. I've watched it change as I go up and down the mountain.

The car actually runs better at lower atmospheric pressure, 12psi, terrible at sea level, 14 psi, and ok at 13 psi.

I think it's got an air leak somewhere so it does better being starved of oxygen. Or it has an easier time detonating 87 at sea level. I moved away from 91 and the IAM got better at elevation but worse at sea level. 91 saw it terrible at elevation and better at sea level. I don't know if 89 would be a good mid ground, might be too much for up here at 5500ft, 87 is probably just right imo but barely ok at sea level.

I still think there's an air leak or something reducing the ECUs coping mechanism just enough so it pulls IAM but no one can find it.
 
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