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I fought some grounding issues earlier this year (and last year, and the year before T_T) while messing around with first one aftermarket ECU and then another. I'll post details in my journal at some point, but all I can say is, the best thing to do is get a complete wiring diagram for your car and just test the wiring segment by segment until you find the issue. It sounds slow and ... well, it's a slow process. But it beats trying to guess what's wrong and then being back to square one when you guess wrong.

Since the TPS isn't reading right (ground offset I assume), that might help you narrow down your search. I know it's frustrating and feels daunting, but if I can figure this stuff out you can too. I'm subbed to this thread now, so keep us updated as you narrow it down and maybe I'll have some ideas as you get closer to the root cause.

Spoilers: It's gonna be some wire headed into a connector that got crimped, damaged or mutilated in some way but has exactly 1 strand still connected. That was it for me. More than once. FML.
 

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Discussion Starter · #42 · (Edited)
I'm back in the game...posted it up for sale out of rage but it'll be running soon. Don't know what I was thinking with that partout ad. I was just frustrated that I screwed something up; I wanted to do things right by not splicing, I bought new pins and was ready to do a quick swap, but life took a different turn now I'm forced to rewire an entire plug!

I tried too hard to take the pins out of the ECU connectors, and now the metal pins are probably not contacting the ecu properly. I gave iWire way too much money for a new "C" connector and will cut the old connector and stick on the new one. Hopefully that'll fix it, I literally did nothing else over the past week that could cause this issue.

Thanks for the motivation gents, I need it.
 

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Discussion Starter · #43 ·
Was too late to mess with the harness but flooring the throttle improved my idle, with AFR's at 15 and running smooth at 1500 RPM, so i guess the coil pack wiring is good! No misfire codes just that persistent TPS high input CEL. Connector is coming Friday, so I'll spend Sat morning mucking about with it.
 

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That sounds consistent with some things I've seen. I've sworn 1 or 2 cylinders weren't firing when running waaaay too rich or waaaay too lean, but as soon as I get things in some kind of 11-16 ballpark everything cleans right back up.
 

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Discussion Starter · #45 ·
That sounds consistent with some things I've seen. I've sworn 1 or 2 cylinders weren't firing when running waaaay too rich or waaaay too lean, but as soon as I get things in some kind of 11-16 ballpark everything cleans right back up.
It sounded like I had 2 coil packs disconnected before I decided to floor it! Scared the hell out of me. But I'm 100% sure I didn't try to get the ign pins out so they will definitely be fine.
 

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Discussion Starter · #46 · (Edited)
Had a very productive day today, got the new plug in. Was super stressed cutting into the harness, a few of the pins didn’t fully click in but she fired up just fine!
Motor vehicle Hood Automotive design Fixture Automotive tire
went all out with the soft Tesa tape to keep everything somewhat organized.
Motor vehicle Trunk Automotive tire Bumper Automotive exterior

And since I don’t trust my own wiring, threw in an extinguisher for peace of mind.
Motor vehicle Cylinder Tints and shades Font Road surface

Test fitted a new eBay radiator, no way will the stock fans fit. Need to get some slim fans for this setup.
Hood Motor vehicle Vehicle Automotive air manifold Automotive exterior

Also wired up and scaled an AEM 3.5 bar MAP sensor, just need to find a better way to mount it without zip ties.
Motor vehicle Automotive fuel system Automotive tire Automotive exterior Auto part

Not bad for 4 hours of work! Super happy I managed to get her back up and running. Now on to MAF tuning….

thanks for the motivation guys!
 

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That's rad! How is that tape to work with? I went with some non-adhesive tape (sealed with self-adhesive tape on the ends of wire runs) for my wire rapping needs but that stuff you have looks 1) nicer 2) sturdier.
 

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Discussion Starter · #48 · (Edited)
That's rad! How is that tape to work with? I went with some non-adhesive tape (sealed with self-adhesive tape on the ends of wire runs) for my wire rapping needs but that stuff you have looks 1) nicer 2) sturdier.
I love the Tesa tape! Be sure to get the original.

There's 2 kinds though so be careful of the application.

The one I used for the cabin harness is kinda soft and fuzzy, but still strong as hell, no way you can rip it like normal tape with your fingers.


The second type is more resistant to heat, and is water resistant, feels like high thread count cloth. Also impossible to rip, have to cut it. I used it on that small section of wiring at the MAP sensor in the above photo, I'll have to tape down that small little piece because I rushed it.


Both are abrasion resistant.

I redid all my engine bay wiring, got rid of the thick plastic sheathing and just went wild with the tape.

Both are great and are easily applied, I recommend it.
 

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Discussion Starter · #50 ·
glad you're back, looking forward to more updates!
Thanks!

Tackling the radiator now. It's 3 times as thick as my piddly stock rad but I will most likely still need fans since my area gets H O T during the summer.

It mounts up perfectly but no room for stock fans. Picked up 2 Spal 12 inch straight bladed ones which fit with an inch to spare! Since the rad already has 90 degree brackets on the ends, I'll just use some 3/16th alum bars to mount them on. Don't wanna half ass it and use those zip ties that just rip out the radiator vanes.

Wiring seems simple. Cut the connectors off the stock fans and will merge the 2 12 v leads into one so it runs full blast whenever the ECU wants to. Harness wiring seems thicker than the Spal fans, so seems like an additional relay won't be necessary!

Thinking of fabbing up a rad shroud of of aluminium, but without a press it might be difficult. Also looking to reduce weight wherever I can, so might just stick with the stock brackets for now, unless I have cooling issues down the road.
 

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Discussion Starter · #51 ·
Threw the new rad in, just a weee bit thicker than the stock one! Used spal 12 inch straight bladed fans, still have a good inch of clearance all around.
Motor vehicle Hood Automotive tire Vehicle Automotive design
Th
Motor vehicle Automotive tire Plant Vehicle Automotive exterior
 

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Discussion Starter · #52 · (Edited)
Cold NY winters prevented me from doing much, but I had some money burning a hole in my pocket so decided to throw in a standalone.

Gadget Font Wood Box Computer hardware

Pinout for both an 04 STi ECU and the Ecumaster Black is below if anyone needs it.

Colorfulness Font Material property Parallel Pattern


Just have to find a subaru ECU header to make the patch harness!
 

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Discussion Starter · #53 · (Edited)
Bought an ECUMaster Black after some goading from a friend of mine, although I quickly discovered no one makes a proper patch harness.

Took me hours in excel and OEM drawings and ended up making my own patch harness, fired up with the first turn of the key.
Circuit component Electrical wiring Gadget Cable Electronic engineering
 

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Saw your other details about the WL stuff.

Been following. Good to see it actually and at least works!

I dont have a read swaybar on mine, its light enough with stiff enough suspension to warrant me not running it... saves a few pounds too.
 

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Discussion Starter · #57 ·
Also put some time into the tune, got a rock solid idle and all my sensors to work. Trying to make a map from scratch is a great learning experience and far easier than using Romraider, changes can be made live and get instant response through the wideband o2.
Took a drive around the block but my tune was far too rich and it broke up at anything over 3k. will need to log a ton to get good data and fix my VE map.
 

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Discussion Starter · #58 ·
Saw your other details about the WL stuff.

Been following. Good to see it actually and at least works!

I dont have a read swaybar on mine, its light enough with stiff enough suspension to warrant me not running it... saves a few pounds too.
WL has been a nightmare for me! Parts not fitting, swaybars misaligned....Wish I could make my own parts cheap, at least I know they would fit.

I'll have to try running without one and see what it's like.
 

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Discussion Starter · #59 · (Edited)
Looks like my swaybar is installed wrong, the bar should attach to the inside of the endlinks, but for the life of me I can’t spread the endlinks wide enough to get it in between, and if I leave one on the inside and the other outside, or both on the outside, the bars rub on the endlinks.

I’m getting really tired of this damn car and nothing fitting properly.
Should have just bought a newer STi and called it a day.
 

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Trust me my friend - these stomp the newer subies in every way!

Looks, performance, all of it. I test drove a fair share and nothing comes close to these.
Keep at it yo, you'll get it. I'm confident in your abilities! Don't let it get you down!
 
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