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Old 12-19-2020, 07:53 PM   #1
JDMRosa04
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Join Date: Jul 2019
Default Help with Front 02 on built STi

2007 WRX chassis and ecu
Has my 07 STI 6 speed and longblock

Basically car has a fully built motor. Iag closed deck. Bc272 g35 turbo and has Id2000cc injectors, Cobb flex fuel kit, speed density, flipped manifold, 4bar map, ets fmic core, custom headers and upipe and custom intercooler piping, tial wastegate and bov, iag tgv delete and some other minor stuff. Proven to do well on my other car.

Trying to get it tuned but have one issue.

Only issue Iím having is the front 02 sensor wonít read. Have a brand new oem sensor. Tried 3 different ones I had and even repinned them in different ways to try to get it to read. Some orientations will read for 1-2 seconds on startup but then go right back to 14.7. AF 1 Current is 1.75. If I repinned it I can get it to 0.12 but still doesnít read any different. Changed SBF 5 fuse as well.
AF sensor 1 just stays pinned at 14.7 but my aem gauge is showing fuel comp is dumping all the way rich and just pegging below 10.0
Pin (1) 0.0 Pin (2) 12.0
Pin (3) 2.8 Pin (4) 2.5v

Iíll legit PayPal someone to help me fix this lol.
Iíve tried everything I can think of to get this figured out! I even pulled every fuse I could find on the car and changed it lol.

ďHad spare fuse box from old carĒ
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Last edited by JDMRosa04; 12-19-2020 at 07:57 PM. Reason: Misspell
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Old 12-20-2020, 06:51 PM   #2
JDMRosa04
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Anyone have any info that can help with this??? Does it matter that the rest of the MAF plug isnít spliced into anything?
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Old 12-20-2020, 07:06 PM   #3
pickleSlapOG
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Run some fresh wire from the o2 to your ecu and see if it works then. If so then your problem is in the harness.
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Old 12-20-2020, 07:21 PM   #4
pickleSlapOG
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Quote:
Originally Posted by JDMRosa04 View Post
Anyone have any info that can help with this??? Does it matter that the rest of the MAF plug isnít spliced into anything?
Do you have a photo of the wireing diagram?
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Old 12-21-2020, 03:04 PM   #5
JDMRosa04
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Quote:
Originally Posted by pickleSlapOG View Post
Run some fresh wire from the o2 to your ecu and see if it works then. If so then your problem is in the harness.
Anyone know where I can find the pins on the ecu for it?
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Old 12-21-2020, 03:04 PM   #6
JDMRosa04
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Quote:
Originally Posted by pickleSlapOG View Post
Do you have a photo of the wireing diagram?
I donít, Iíve tried to find it but canít
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Old 12-22-2020, 01:56 PM   #7
spoolinsti05
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I've been using aem ems pinout to trouble shoot things. If that helps any..

I've also had issue where my power supply to relay box under hood was loose. Unbolt box pop lower cover off relay/fuse box and check the 10mm bolt is snug. Probably should disconnect battery I however didn't. If you're careful you won't short it out.

Also had pin tension issues on fuses in that same relay box. Had to bend the terminals so they hugged tightly to pins for relays and whatnot.

Anyhow that harness is run past the turbo into the firewall. That spot gets super hot and can brittle those wires in no time at all. Start with basics connection issues. Then dive into the harness and check for hard brittle unbendable wires. Those are usually the bad wires.
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