Codes....All of the Codes....And odd engine feel.
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This is a discussion on Codes....All of the Codes....And odd engine feel. within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; 2003 WRX Wagon, EJ257 block with EJ205 heads machined out, 2010 STi Injectors, 255 LPH Walboro Fuel Pump, TBE, No ...

  1. #1
    Registered User Pylonpounder's Avatar
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    Codes....All of the Codes....And odd engine feel.

    2003 WRX Wagon, EJ257 block with EJ205 heads machined out, 2010 STi Injectors, 255 LPH Walboro Fuel Pump, TBE, No Cats, blah blah blah.

    For quite a while I've had the code P0031-Front 02 Sensor Low Input. That, I'm not worried about- I have an Innovate LC-1 wideband kid, and it appears as though there is a wiring problem between the little computer that the O2 sensor hooks up to, and the gauge itself (Guage constantly blinks 7.4, logging with RomRaider will give me good AFR Numbers, And there is power on the sensor side of the LC-1 computer unit thingy, so I'm assuming wiring problem somewhere in the return lines from the LC-1 computer. But, irrelevant, I'll figure that out. Though advice would be nice if anyones got any.)

    Then, I started throwing the TGV-1 System Closed code-ouch. Limp mode. No fun. Replaced that TGV motor- No difference. Replaced that TGV sensor- and the System 1 Closed code went away, but on came P1088- TGV Pos. 1 Sensor Low Input. I am now on my 3rd (And have a 4th at the ready) TGV sensor. I have two new connectors to wire into the harness for it if necessary. When logging with RomRaider, the System 2 sensor (I.E. Drivers side) Will give me values, while the system 1 (Right Side) TGV Position sensor will not give me any values. But..I've replaced with brand new, with several used but functioning....I don't get it.

    This causes an issue because it drives fine normally- but if I go anywhere near high(ish) boost, It starts to...I don't know how to discribe it. Jitter. Almost like a jittery Misfire, but..not really a misfire. I noticed today a discrepency in a few things- My boost guage (A crappy one....) Will read 15 at the max, but it gets that "jittery" feeling around 10-11 PSI. But logging with RomRaider, The target boost climbs all the way to 18.89- which is right about where EFILogics tuned it to be a few years back.

    Up until I started writing this, I was thinking "Ahh, well, there must be a vacuum leak between the turbo and the boost gauge, if my gauge is reading so low!" But now, I realize that the parameter I was logging is entitled "Target Boost". Now, I'm pretty new to playing with Open Source tuning and Logging in detail and things- But it seems to me that "Target Boost" Would be the boost that it is instructed to reach by the ROM loaded onto the ECU, not the actual boost being acheived as I was first thinking. Which makes me wonder why I'm not hitting full boost as I should. (I did replace the turbo since being tuned- was tuned with a factory subaru TD04L-13T, replaced it with a cheaper brand Td04L-13T..But I have the waste gate as tight as it will go, and unless i'm wrong and "Target Boost" is actually the full PSI I'm reaching, I can't figure out why I'm not reaching full boost, and why it gets so...jittery under boost).

    Then today, I replaced the TGV Pos. 1 Sensor yet Again- And for a little while atleast, P1088 Stayed away. Only to be replaced inexplicably, by the code for "IAT sensor reading high". Now, using the diagnosis process in the factory service manual, according to the 1st step (Is it reading higher than 90-something? Which yes, mine was) I'm supposed to "Repair poor connection in MAF, MAF Connector, or the battery harness between MAF and ECU. According to the other steps (Yeah, I did them anyway), 2-4 check out fine; 5, however, says to measure the resistance between pin 5 on the maf connector and an engine ground, and if less than 5 Ohm, replace the MAF. But..The MAF is less than 2 weeks old, brand new. Replaced it not even two weeks ago because I was getting the code for IAT Sensor low input. Havent had an IAT or MAF code since I replaced the MAF, up until today when I replaced the TGV sensor on the right side (Again). But, as its a memorized code, I'm thinking that was my fault- when filling the coolant I did start it without the MAF connected for a moment to be able to more quickly fill the coolant. Cleared the code several times, and eventually it went away- and has stayed away, to my knowledge (Computer started bugging out and I couldn't log it anymore tonight). So, clearly that code stuck around because its a memorized code that the ECU needs to make absolutely sure is fixed before it goes away.

    But then, right around the time that the IAT code goes away...Along comes our friend P1088, TGV Pos. Sensor 1 Low Input. According to the service manual, this can cause poor idle (Mine idles fine), Stalling (Nope) or poor driving performance (You betcha.) But, the service manual simply says "replace the TGV System.". I..am at a total loss here. I'm wondering if perhaps I set the TGVs in the wrong position before remounting the motor and then the sensor, which doesnt really seem all that possible...I just don't know. I believe that code is causing my stuttering/jittery issue under WOT/Decently high boost, but I cannot make it go away no matter what I try. I'm going to fix a few things that I believe may be causing miniscule vacuum leaks tomorrow, but I don't think the (potential) vacuum leaks would be big enough to make an issue. I'm also probably going to pull the whole TGV system off of a Forester XT that is at my disposal (And hope they happen to be the same- if not, I guess I'll sell them on ebay, it's free if I pull it so why not try, right?)

    But...I just...I don't know. I'm at a loss. My Ideal fix here is to get my AP rebuilt, and edit my map using the AP race tuner so that there are no TGV codes after doing some form of TGV Delete..But first I have to get the AP rebuilt. So for the moment, I just have absolutely no idea.

    If anyone has any idea what the heck is going on or how to fix it, that would be fantastic.
    If there's any parameters anyone would like to see logged that may help troubleshoot, say the word and I'll log it ASAP and post the results.

    I'm really, really, really sorry for such a huge post guys- I just really don't know what the hecks going on, and felt that all that backinformation was fairly important.

    Thank you, and I really hope someone (atleast one out of those few who bother to read this novel anyway ) has some idea of what's going on here, or if I'm doing something wrong while replacing the sensor, or...I just don't know. I really don't.

    Thanks again in advance for the help I'm sure I'll receive from those far more knowledgable than me!

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  3. #2
    Moderator Donkey's Avatar
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    Did you preload the TPS/TVG sensors when you put them on? Also I would check to make sure all of the factory engine grounds are hooked up. Kinda sounds like you have a ground issue possibly. Do you have a grounding kit installed?
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  4. #3
    Registered User Pylonpounder's Avatar
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    I do not have a grounding kit installed. As far as I'm aware, the TGV motor/Sensor are preloaded properly- I removed both, set the TGVs so that the pin the sensor sits on will rotate the way that winds the spring in the sensor, installed the motor to hold them still, and then installed the sensor. I could check and clean all my grounds, but I believe they are all hooked up. There's intense boost oscillation when it gets "jittery" as I put it- not intense in the sense of wide variation, but small and extraordinarily rapid.

    Edit: If I have to have the sensor's spring wound up (loaded) when installing it, rather than having it set so that when the TGV motor moves the TGVs it loads the spring....I don't really know how I'm going to do that, atleast not easily. My turbo (and turbo inlet) are both very much in the way of placing the sensor on the pin and then twisting the sensor to load it. If necessary I'll pull the turbo, set the TGV's in the closed position, put the sensor on the pin and turn it so that it's loaded and and then install the motor, but that doesn't make too much sense to me. And I can find very little information on replacing TGV motors/sensors since pretty much everyone just does the delete- Which I will do, once I get my AP rebuilt.
    Last edited by Pylonpounder; 08-06-2014 at 06:17 AM.

  5. #4
    Registered User Pylonpounder's Avatar
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    Anybody got any more ideas? Maybe something I could log to help discover the issue?

    I regrettably did not get the chance to play with the grounds today, much as I wanted to- way too much other work going on. I will do that tomorrow in all likelyhood. I will also go through the diagnosis steps in the factory service manual and see exactly where the issue lays (atleast, as indepth as the service manual goes) in regards to the TGV sensor code.

    One last thing- Just to sate my curiosity, can someone explain how a ground problem could cause the issues\symptoms I'm having? I can't see it lowering the boost (though im sure the tgv sensor code could, though the sensor codes don't put it in limp mode, and I'm sure a ground issue could very easily cause the TGV sensor code), but...Well I guess this is pretty hypothetical. If the driving issues (low boost, insanely quick boost oscillation, all while feeling like...Not misfiring necessarily, more like just not firing period on a cylinder- but only at 35%+ or so throttle, or 10+ PSI regardless of throttle [Hey, it's a td04 on a 2.5 hybrid, boost happens whether I want it to or not, even at less than 10% throttle once im past 3,000 RPMs] ) are unrelated to the TGV code, could a ground issue cause that? I dont see how, and I'm pretty good with vehicles and with electronics/wiring, but I certainly don't claim to be an expert of any form, so any new imformation I can pick up would be wonderful.

    Thanks again for your attempts to help guys! Im so confused by this as this point.

    And if someone could give me a detailed step by step for replacing the TGV sensor, that'd be great too. Not the whole process, just.. TGV's open, or closed when sensor gets put on? And should the sensor spring be loaded when installing while TGV is in said correct position for installation, or should the action of the TGV motor moving the TGV be what loads the spring in the sensor? To me it makes sense that the motor opening the TGV should load the spring, so that it closes automatically- but considering that they do spend the majority of the time open, it would make sense the other way too. I'm just a little lost here, and can't seem to find anything that gives me the little bits of information I need

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