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Old 06-02-2013, 09:04 PM   #26
VictorOfHavoc
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Quote:
Originally Posted by SwedeSTi View Post
datalogs uploaded to google docs:

Baseline throttle (proper operation): https://docs.google.com/spreadsheet/...kE&usp=sharing

Consistent variation throughout log: https://docs.google.com/spreadsheet/...Wc&usp=sharing

Significant throttle change: https://docs.google.com/spreadsheet/...3c&usp=sharing

These 3 logs represent the three I mentioned in my previous post.

seeing makes things easier to understand. so this seems like it might be related to either the relay or the throttle plate now. I previously though it was much more constant than what the logs show so I thought electrical only. Have you thought about inspecting the throttle plate too? possibly leaking in the intake manifold?
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Old 06-03-2013, 04:13 AM   #27
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seeing makes things easier to understand. so this seems like it might be related to either the relay or the throttle plate now. I previously though it was much more constant than what the logs show so I thought electrical only. Have you thought about inspecting the throttle plate too? possibly leaking in the intake manifold?
A leak in the intake manifold would (theoretically) cause issues during boost. Knock on wood, but I have no issues holding target boost nor any whistling or anything like that under boost that would indicate a leak on the manifold side of the turbo.

I may be mistaken on what you're referring to when you say "throttle plate", but the throttle body should have zero issues since it was replaced with a new one probably 2500 miles ago by the dealership.

I drove the car today while running some errands. Car started out a bit rough. I didn't datalog it during this time, but I had my AP hooked up and I was monitoring throttle position. EVERY time I start having problems, throttle position starts jumping around. But on the way home, car drove just fine. No throttle fluctuations at all and I was driving the exact same way I drove while it was happening (light throttle, 35-45mph). I did get a couple of datalogs on the way home documenting the steady throttle.

The problem is intermittent. There isn't a single thing that I have thought of that could cause the problem that hasn't been checked, other than an intake leak (which I don't understand how it would cause the data I'm seeing). Weather? Nope, happens at <40 degrees and >95 degrees. Compensation for the A/C condenser turning on? Nope, driven with the fan off (disabling the a/c altogether). Possible foul up with the throttle mapping on my tune? Nope, loaded the tune with stock throttle mapping. Throttle body gears worn? Nope, replaced throttle body. O2 sensor? Nope, replaced it. Battery voltage? Shouldn't be, battery is new. Bumpy roads? Nope, drive the same roads almost every time I drive it and sometimes it's fine, other times it's hellish. Tune? My tuner rode with me while I drove for 45-60 minutes monitoring the ECU and said he sees no issues with the tune. Cobb has also seen the tune and mentioned nothing about the parameters other than a guess about the throttle mapping (said the tuned throttle map is linear, but it was worth trying just to rule it out). Nothing fixed the problem. It intermittently shows up, sometimes worse than others. There is no CEL and no indication of where to look other than the throttle system.

I am an industrial mechanic and work on electrical, pneumatic, hydraulic, and mechanical systems of printing presses, corrugators, and box-making equipment. In my experience, mechanical problems are pretty consistent. Electrical problems, however, can be a little more intermittent. We run into sticky relays relatively often. Based on my understanding of how the systems of the car work, and taking my experience into consideration, electrical problem seems the most likely. The chances of burning through the insulation of the wiring without blowing fuses is pretty slim, and the chances of burning/wearing through insulation between 2 wires without shorting out is even slimmer. This is what would have to happen for a short to cause the INCREASE in throttle, because opening the throttle requires an increase in voltage. Is it impossible? I guess not, but it's far from likely. Until I posted this thread, I had no idea there was an assembly between the ECU and the throttle body. In electronics school, during troubleshooting they teach you that between the good and the bad is the ugly. For this case, the ECU is the good (not calling for the change), the throttle body is the bad (fluctuating throttle position). Only thing between the two is the wiring harness and the throttle relay, and the relay is WAY easier to change than the harness, unless the part can't be ordered. I should hear from the dealership tomorrow so we'll see what happens...
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Old 06-03-2013, 09:17 AM   #28
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I really meant body not plate . Typing late at night isn't my strong suit haha. You're definitely right that intermittent problems are usually electrical.

A friend of mine had a boost leak when one of his hoses was collapsing in on itself. Data logs showed no boost fluctuations while holding steady but sometimes it would fluctuate and the car just didn't feel right. Small boost leaks don't always make noise but i learned from that experience that they can wreak havoc.

Also, I really do recommend just pull all the associated fuses and replace them... I've worked with electronics for a very long time and I've seen brand new perfect looking fuses act up. They're a cheap easy step so there isn't much to lose. I'm not 100% that's your problem, but for 5 bucks in fuses what do you have to lose?
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Old 06-03-2013, 11:13 PM   #29
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I really meant body not plate . Typing late at night isn't my strong suit haha. You're definitely right that intermittent problems are usually electrical.

A friend of mine had a boost leak when one of his hoses was collapsing in on itself. Data logs showed no boost fluctuations while holding steady but sometimes it would fluctuate and the car just didn't feel right. Small boost leaks don't always make noise but i learned from that experience that they can wreak havoc.

Also, I really do recommend just pull all the associated fuses and replace them... I've worked with electronics for a very long time and I've seen brand new perfect looking fuses act up. They're a cheap easy step so there isn't much to lose. I'm not 100% that's your problem, but for 5 bucks in fuses what do you have to lose?
True. I guess it wouldn't hurt. I need to see if the mechanics at the dealership have any sort of communication with techs higher up the Subaru food chain that may be able to give us some direction. By the looks of the diagram they emailed me, the throttle relay looks like it provides an input to the ECU enabling throttle control, but I could be wrong.

If that's the case, it looks like it could be the ECU...
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Old 06-04-2013, 07:01 AM   #30
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This might not fix the issue but try putting the stock airbox back in cuz ever since I installed my Cobb SF+box I've had similar issues.
My tuner was able to tune some of this out but is still present and havnt had a chance to put the stock airbox back in to see if this clears the issue.
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Old 06-04-2013, 10:34 PM   #31
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True. I guess it wouldn't hurt. I need to see if the mechanics at the dealership have any sort of communication with techs higher up the Subaru food chain that may be able to give us some direction. By the looks of the diagram they emailed me, the throttle relay looks like it provides an input to the ECU enabling throttle control, but I could be wrong.

If that's the case, it looks like it could be the ECU...
When they get back to you on the throttle relay part number do you mind posting it? I am having an issue with the throttle control circuit that is different but you are troubleshooting many of the same things I am. It's much appreciated and good luck, I'll be following this thread to see its resolution.
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Old 06-07-2013, 01:54 PM   #32
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well????????
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Old 06-08-2013, 12:34 AM   #33
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well????????
I haven't gotten a part number from the dealership. They just said it'd be $44 out the door and they'd have to order it (this is via email). I'll call on Monday and get the part number.

As far as the throttle problem is concerned, I emailed Element Tuning since they deal heavily with the Hydra Nemesis standalone and are well versed in the WRX/STi platform. I got lucky and he replied to my email saying they had a similar issue with one of their race cars they were running the hydra on. He said it gave them a DBW failure so they had an idea where to start (unsure why my ECU hasn't given the same fault). He said they had a bad ground, so they twisted the ground pin on the connector to make better contact. I'm going to give that a try tomorrow when I get a chance and see what happens. I'll let you guys know what happens.
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Old 06-14-2013, 01:30 AM   #34
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All right, managed to do a bit of troubleshooting this past weekend. I took a shot in the dark since I'm not throwing any codes and used the troubleshooting matrix for an issue with the throttle body that sounded closest to my problem (I don't have the DTC right now and I don't remember it). Didn't find anything out of the ordinary in the wiring. The only thing I ran into was the value for a voltage reading at the throttle body. At one point in the manual it states reading from pin 5 at the throttle body connector to ground I should read between 4.5-5.5V, which I do. Two or 3 steps later it says read the same pin looking for 10V... My guess is the manual is incorrect (there were other things that were incorrect also). I believe the manual I found was for an '04 WRX/STi, but everything I've seen says they should be the same. Either way, didn't get anywhere.

After hooking everything back up, I started the car and was throwing 2 codes (p0123 and p0223, if I remember correctly). I cleared them with my AP and they didn't come back so I'm guessing it was from having the ignition on with the connectors disconnected.
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Old 06-14-2013, 11:07 AM   #35
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We have had this problem for years on our bone stock 07 STi. The dealer choouldn't replicate the problem and it drives me nuts.

In my opinion FHI did a poor job with the mapping for the DBW throttle, but I can't pin down the source of the surging.
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Old 06-15-2013, 04:38 AM   #36
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We have had this problem for years on our bone stock 07 STi. The dealer choouldn't replicate the problem and it drives me nuts.

In my opinion FHI did a poor job with the mapping for the DBW throttle, but I can't pin down the source of the surging.
It is annoying as hell! Not being able to figure out what the hell the problem is is the worst part. You've never thrown any codes??

Here is a copy of the email I received from Element Tuning about the issue:

--Shame on your oem ecu for even allowing a 8% variation in throttle to pedal span! Really that should be considered a dbw failure and we never allow that in our Hydra EMS.

Given what you've told me it sounds like a grounding issue for the throttle and it's probably at the connector itself. On my race car we had to twist the pin slightly on the black wire I believe to get a better connection. My had a Hydra so when the throttle does what yours did it shuts the throttle down so for me it was easy to tell when I found the correct pin to tighten.

Good luck.--

I have yet to figure out which pin it is because I don't completely understand how the wiring is laid out to the throttle body. There are 6 wires, part of which are for the servo and part are for the throttle position sensor. There is a "main" and a "sub" signal but I have no idea what that means.

Here is the manual I was referring to for troubleshooting:

http://ken-gilbert.com/wrx/STi_Manual/index.htm
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Old 07-06-2013, 06:25 AM   #37
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All right so I've been driving to work the past few days because it's been ridiculously hot outside (105+ to work and 85+ on the way home). The car drove just fine for the past few days. Other than one little blip, I had no issues for 3 days of commuting (about 85 miles round trip). Today, however, was a different story. Going to work it was mid-90s and I didn't have any issues. When I left work, it was in the upper 70s. First thing I noticed was idle when I first turned the car on didn't hit about 1800rpm and hold steady like it had been for the past few days. It started no problem, hit maybe 1700rpm, dropped slightly then went back up; subtle but I noticed it. On the drive home, had probably 10 surges. Still no idea what is causing them. The only thing that has changed is the weather. I have noticed this before but don't understand why a change in temperature would cause the surging. Electronics work better in cooler temperatures, and mechanical issues would be way more consistent...

I did pull the throttle plug off about 2 weeks ago and slightly bent all the pins on the throttle body to make sure I was making solid contact with the connector, so I don't think that's the issue. The only things that have changed from the past few days to today is the outside temperature and my fuel level (still have a little less than 1/4 tank).

I'm at a complete loss. I did mash on it a bit when I got off the freeway. It ALMOST makes me forget about the surging lol.
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Old 07-17-2013, 05:47 AM   #38
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All right, so I drove to work on Friday because I needed to pick up some things on the way. Right off the bat I noticed that the car didn't start up and hit and hold ~1700 RPMs ('cold' start). It was about 95 degrees at this point in time. On the way to work, it started acting up randomly. Not nearly as bad as I've seen it, but still there. On the way home it did the same thing (temperature was down in the low 70s). This pretty much blows my temperature theory out of the water.

I have noticed that at a given vacuum level while driving, I can sometimes be maintaining a constant speed and sometimes decelerating. I haven't logged anything with ignition timing or anything like that because the throttle position is so screwy and happens EVERY time the car starts surging. Could the car possibly be going into limp mode without me knowing? Since I'm running a MBC, the ECU can't control boost as it normally would when in limp mode, buuuuuut also wouldn't affect the throttle position like I'm seeing...

ANYONE HAVE ANY IDEAS?? What are the chances the ECU is taking a dump?
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Old 07-17-2013, 06:28 AM   #39
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actually, what is the possibility of another component that is electrically linked to the throttle causing this issue? According to the schematic I referenced in a previous post, the red wire at the throttle body is connected to the pressure sensor (not sure what this is), both TGVs, and the accelerator position sensor. However, I'm not positive what this wire is (the schematics don't indicate anything other than wire color and pin number at a given module/connector). The red wire is linked to pin 16 on connector B136 on the ECU. Could I have another sensor tanking a dump without me knowing it??

The other wire is the black and green wire which is also tied to a handful of other sensors ultimately terminating at a sensor/shield ground.

Here are the schematics I'm referencing:

https://drive.google.com/folderview?...lU&usp=sharing
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Old 07-17-2013, 12:30 PM   #40
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Hey man, quite a bit of what you've been doing has gone above my head now, but in the spirit of trying to help...

I was reading about a surging issue recently (tried to find it again, but couldn't) on my phone and I thought of this thread... The issue they had was the waste gate was getting stuck randomly. Have you looked into your waste gate at all? and possibly your dp gasket?
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Old 07-17-2013, 11:13 PM   #41
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Hey man, quite a bit of what you've been doing has gone above my head now, but in the spirit of trying to help...

I was reading about a surging issue recently (tried to find it again, but couldn't) on my phone and I thought of this thread... The issue they had was the waste gate was getting stuck randomly. Have you looked into your waste gate at all? and possibly your dp gasket?
I haven't checked it, no. I originally thought the rotating assembly in the turbo was possibly rubbing on the housing or I have coked oil in the bearing housing. The surging is under vacuum so my waste gate should be closed anyway. Unless it's leaking by 90% of the time and closes when it surges...? That would make sense based on the changes I'm seeing on the boost gauge, but still doesn't really explain the throttle position variation.

Does anyone know what the hose that attaches to the throttle body is for??
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Old 07-18-2013, 12:16 PM   #42
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I haven't checked it, no. I originally thought the rotating assembly in the turbo was possibly rubbing on the housing or I have coked oil in the bearing housing. The surging is under vacuum so my waste gate should be closed anyway. Unless it's leaking by 90% of the time and closes when it surges...? That would make sense based on the changes I'm seeing on the boost gauge, but still doesn't really explain the throttle position variation.

Does anyone know what the hose that attaches to the throttle body is for??
it could be stuck partially open and never fully close so the throttle body tries to compensate?

I believe that's a coolant line. There should be an outlet at the bottom
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Old 07-19-2013, 03:17 PM   #43
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it could be stuck partially open and never fully close so the throttle body tries to compensate?

I believe that's a coolant line. There should be an outlet at the bottom
I'm not sure, but I guess it's not out of the realm of possibility.

It could be a coolant line. I need to break out my original throttle body and look at it again. Any idea why they would run coolant through the throttle body?
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Old 07-19-2013, 07:05 PM   #44
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I bypassed the coolant line on my 05 to keep the intake temp down don't think it has to do with coolant line possible motor problem on car
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Old 07-19-2013, 08:25 PM   #45
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I'm not sure, but I guess it's not out of the realm of possibility.

It could be a coolant line. I need to break out my original throttle body and look at it again. Any idea why they would run coolant through the throttle body?
The coolant line is there as more of a warmant than a coolant but that's not a word ... It keeps the throttle body from freezing over in the winter... we're talking 45 degrees can actually get it to freeze over and cause problems...
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Old 07-19-2013, 11:14 PM   #46
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The coolant line is there as more of a warmant than a coolant but that's not a word ... It keeps the throttle body from freezing over in the winter... we're talking 45 degrees can actually get it to freeze over and cause problems...
I see. Makes sense you wouldn't want that freezing lol
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Old 07-20-2013, 04:20 AM   #47
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I bypassed the coolant line on my 05 to keep the intake temp down don't think it has to do with coolant line possible motor problem on car
Care to elaborate on that? I've already determined that there is a problem lol
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Old 07-23-2013, 06:57 AM   #48
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Drove to and from work on Saturday. Other than a handful of quick surges on the highway, she drove very well. I had my AP hooked up on the way home and was going through the parameters list in an effort to catch something sporadic. Watched ignition timing, fuel pump duty, tgv voltage (L and R)...didn't see anything. Problem was it was driving well for about 99% of the drive. Temperature was actually fairly cool, low to mid 70s if I remember correctly. So the saga continues...
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Old 07-25-2013, 07:45 PM   #49
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I'm having the same issue. Although it happens intermittently, I've noticed the issue happens more frequently after a hard acceleration. The problem is fixed by turning the car off then back on. A resolution to this would be great.

car model: 2005 sti
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Old 07-26-2013, 01:23 AM   #50
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I'm having the same issue. Although it happens intermittently, I've noticed the issue happens more frequently after a hard acceleration. The problem is fixed by turning the car off then back on. A resolution to this would be great.

car model: 2005 sti
Do you also have a throttle body bypass?

I think if both you and the OP have the exact same issue a list of mods should be compared...maybe there's something in common?
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