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Discussion Starter #1
Hello all. I really need some help here. I have an 05 STI that I have fully rebuild and power comes on good feels reliable and delivers as advertised. Unless I make a left hand turn at like an intersection at about 20 mph. The problem is the car seems to drop to idle and no matter how hard i press the pedal the car will not gain speed until the car becomes straight or half way into the turn. I would say this happens approx for 1 to 2.5 seconds and it is very annoying. Oh by the way never has a check engine light or any other light come on when this happened. I’m at a loss here. I have checked the following

fuel pressure stays steady
Car not knocking
Dam 1.000 or 1000 I forgot whats normal
Tried this with a full tank still sometimes does it
Monitored accelerator pedal and Throttle position sensor and they both work fully.

I have 1300cc id with a aem 340lph brand new fuel lines. I rebuilt the car and do not know everything. Now before i leave this open to suggestions i believe that this has happened before I did the rebuild.

Can anyone seriously point me in the right direction for troubleshooting this?
 

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Discussion Starter #2
Also if I’m starting to have a faulty longitudinal or g sensor shouldnt i get a CEL
 

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Power steering issue?
 

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Very interesting. So are you saying that this happens less when you have a full tank of fuel, and more often when you do not have a full tank? When the issue is happening, is there any kind of bucking or hesitation? Like a fuel cut/starvation?
 

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If it was a power steering issue shouldnt i be getting the clunking and shouldn’t the steering wheel lose its turning capabilities (slower turning)?
Not so sure about clunking, but signs, yes. It was only something to ask.

Very interesting. So are you saying that this happens less when you have a full tank of fuel, and more often when you do not have a full tank? When the issue is happening, is there any kind of bucking or hesitation? Like a fuel cut/starvation?
How bout something with a fuel or vacuum line around the steering mechanism?
 

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Discussion Starter #7
Very interesting. So are you saying that this happens less when you have a full tank of fuel, and more often when you do not have a full tank? When the issue is happening, is there any kind of bucking or hesitation? Like a fuel cut/starvation?
So It happens regardless of how much fuel I have. And when it does there is no bucking or any hesitation. No knocking so I’m pretty sure its not a fuel thing. i just lose all acceleration and then it kicks back in after a second to 1.5 seconds. This doesnt always happen but I would say if I’m out on a drive and have to make a 90 degree left turn I would say 1 out of 4 times it will do this.
 

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This happens when your are trying to "accelerate" or at least hold speed in the turn - I mean you wouldn't know it if your foot wren't on the pedal - correct?

I would start by checking fuel pressure, regulator and the vacuum line to it.
You don't have an AP, but don't have any warning or codes

Throttle position sensor? Hmm Throttle motor? Don' know of anyone who's ever had em go bad?
 

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Discussion Starter #9
Also sorry i missed the second half
This happens when your are trying to "accelerate" or at least hold speed in the turn - I mean you wouldn't know it if your foot wren't on the pedal - correct?

I would start by checking fuel pressure, regulator and the vacuum line to it.
You don't have an AP, but don't have any warning or codes

Throttle position sensor? Hmm Throttle motor? Don' know of anyone who's ever had em go bad?
i believe this happens when I’m trying to hold speed in the turn. I have an AP and have been monitoring the accelerator pedal, throttle position voltage, and also the sensors positions and what percent they are running. So when i lost power i stared at the AP and saw that both sensors are receiving consistent signal and not dropping or growing without actual input. This is why I’m confused as to what it could be. I just bought both G sensors to try and rule that out. Fuel pressure, vacuum line to regulator are brand new and tight on so I believe this isnt the issue. I bought the sensors thinking that when I make the turn the car is “thinking it has surpassed the allowable g limits” and putting the car into limp mode or failsafe mode and then the car’s sensor reads a normal value and gives me power back. I dont know if I’m thinking to far into but if it will get rid of the issue idc.
 

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So It happens regardless of how much fuel I have. And when it does there is no bucking or any hesitation. No knocking so I’m pretty sure its not a fuel thing. i just lose all acceleration and then it kicks back in after a second to 1.5 seconds. This doesnt always happen but I would say if I’m out on a drive and have to make a 90 degree left turn I would say 1 out of 4 times it will do this.
This happens when your are trying to "accelerate" or at least hold speed in the turn - I mean you wouldn't know it if your foot wren't on the pedal - correct?

I would start by checking fuel pressure, regulator and the vacuum line to it.
You don't have an AP, but don't have any warning or codes

Throttle position sensor? Hmm Throttle motor? Don' know of anyone who's ever had em go bad?
Hmmmm, i dont know about throttle, he says this only happens on a left turn only. A 90 degree left, sounds like a pretty sharp turn to me. Im starting to suspect maybe binding on the steering shaft joint. I think this one will be hard to figure out over the internet. Especially with no faults or warning lights.

To the OP, how does the steering wheel feel? Does it try and return to a normal position or does it stay stuck in a turnt position making you have to manually turn it back?
 

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Discussion Starter #11
Hmmmm, i dont know about throttle, he says this only happens on a left turn only. A 90 degree left, sounds like a pretty sharp turn to me. Im starting to suspect maybe binding on the steering shaft joint. I think this one will be hard to figure out over the internet. Especially with no faults or warning lights.

To the OP, how does the steering wheel feel? Does it try and return to a normal position or does it stay stuck in a turnt position making you have to manually turn it back?
It tries to return back to normal and by 90 degrees i mean like making a left at a light
 

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Hmmmm, i dont know about throttle, he says this only happens on a left turn only. A 90 degree left, sounds like a pretty sharp turn to me. Im starting to suspect maybe binding on the steering shaft joint. I think this one will be hard to figure out over the internet. Especially with no faults or warning lights.
Exactly - I agree


just coming up with possibilities . . .
 

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Discussion Starter #14
VDC did not come to the US till 2008. Do you have that on your 2005? Otherwise why would you have G sensors?
While I dont have VDC. There are still 2 g sensors in the 2005 sti located in/under the center console. This is the only thing I can think of since it happens while turning. I could be wrong but willing to rule this out while only spending 100 bucks
 

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While I dont have VDC. There are still 2 g sensors in the 2005 sti located in/under the center console. This is the only thing I can think of since it happens while turning. I could be wrong but willing to rule this out while only spending 100 bucks
Don't blame you.
Are they crash sensors? If so for airbags not VDC.
I'll look into it if I can perhaps at lunch.
 

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Discussion Starter #18
Yeah so went to take it apart and the lateral sensor plug doesnt come apart without cutting it I believe. I know it sounds crazy but I was there smh. I’ll look again later this week and as for power steering my steering wheel doesnt return to the straight position. So I’ll be picking that up today and hopefully installing this weekend. I’ll keep you guys updated on my project
 

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as for power steering my steering wheel doesnt return to the straight position. So I’ll be picking that up today and hopefully installing this weekend.
I'm going to catagorize the above as missing information in the original post. Not sure what are are picking up, gonna guess a steering rack. Anyone want odds that it fixes the to original issue?

Power steering issue?
 
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