|
|
|
|
Thread Tools | Display Modes |
04-20-2023, 05:12 PM | #1 |
Scooby Newbie
Member#: 533971
Join Date: Apr 2023
|
Alternator affecting AFR's?
Hello everyone, For the past year and a half of 07 STi ownership I have been trying to figure out why my afr's bounce around all crazy during idle. AFR's will swing from 13 to 17 and go back and forth and never settle at a nice smooth 14.7. Ive tried everything from a parallel fuel line kit, new afr sensor, new maf etc. I eventually gave up and then decided to make a facebook post asking for help one last time before taking it to a shop.
Someone ended up recommending that I disconnect the green plug on the alternator and let it idle and see if that helps anything. I unplugged it and it idled like a brand new car, like ive never ever seen before. So, I replaced the alternator with a 110A from NAPA and i have to say it is definitely better, but not as good as it was when unplugged. So, has anyone encountered an issue like this? My theory is that a diode in the alternator went bad and started introducing AC Current into the system and messed with the ECU??? I think I will start by checking the wiring in that circuit as well as clean all grounds that I can find. Any more advice would be greatly appreciated!
* Registered users of the site do not see these ads.
|
04-21-2023, 07:12 AM | #2 |
Scooby Guru
Member#: 428511
Join Date: Aug 2015
Location: philadelphia
Vehicle:2016 STI |
it's never going to sit at 14.7 BTW
|
04-21-2023, 07:59 AM | #3 |
Scooby Newbie
Member#: 533971
Join Date: Apr 2023
|
|
04-21-2023, 09:09 AM | #4 | |
Scooby Guru
Member#: 428511
Join Date: Aug 2015
Location: philadelphia
Vehicle:2016 STI |
Quote:
that is theoretical PERFECT stoich, no gas engine can run dead on 14.7 and they'll all swing around simply due to how it is read it's not like reading coolant temp or something, it will never sit stable is it actually running poorly? |
|
04-21-2023, 09:50 AM | #5 | |
Scooby Newbie
Member#: 533971
Join Date: Apr 2023
|
Quote:
|
|
04-21-2023, 01:35 PM | #6 | |
Scooby Specialist
Member#: 47143
Join Date: Nov 2003
Location: Toronto
|
Quote:
Sent from my SM-G975W using Tapatalk |
|
04-21-2023, 03:55 PM | #7 |
Scooby Guru
Member#: 428511
Join Date: Aug 2015
Location: philadelphia
Vehicle:2016 STI |
|
04-21-2023, 08:08 PM | #8 |
Scooby Specialist
Member#: 29292
Join Date: Nov 2002
Chapter/Region:
SCIC
Location: Orange County CA
Vehicle:2004 WRX wagon silver |
what injectors are you running?
|
04-22-2023, 08:09 AM | #9 |
Scooby Newbie
Member#: 533971
Join Date: Apr 2023
|
ID1000. and trust me, afr's are all over, causing misfires from being lean. Only have issues at idle. Tuner cant figure it out. Based on logs, as soon as it is in closed loop, it starts leaning out, fuel correction maxes to plus 25% and misfires. But thereafter fuel trims trends out of range negative as if its running too rich.
|
04-22-2023, 11:43 AM | #10 | |
Scooby Specialist
Member#: 47143
Join Date: Nov 2003
Location: Toronto
|
Quote:
Sent from my SM-G975W using Tapatalk |
|
04-22-2023, 12:01 PM | #11 |
Scooby Specialist
Member#: 510366
Join Date: Jan 2020
|
OP Do you have a log?
Are you the tuner and mechanic? |
04-23-2023, 12:06 AM | #12 | |
Scooby Newbie
Member#: 268286
Join Date: Dec 2010
Chapter/Region:
W. Canada
Location: Alberta
Vehicle:2011 STi Dark Grey |
Quote:
That green plug does is the sense the system voltage. If the lead is unplugged the alternator will run at 100% output. Have you load tested the battery? Autozone or whatever will do it for free inside the car. If the battery is more than 4 years old I'd probably replace it anyway. Have you hooked up a mechanical fuel pressure gauge to see whats happening? Have you logged fuel pump duty cycle after its done running at 100% and compared it to symptoms? Full list of mods would help. |
|
04-24-2023, 02:32 AM | #13 | |
Scooby Specialist
Member#: 29292
Join Date: Nov 2002
Chapter/Region:
SCIC
Location: Orange County CA
Vehicle:2004 WRX wagon silver |
Quote:
|
|
05-20-2023, 10:06 PM | #14 |
Scooby Guru
Member#: 108051
Join Date: Feb 2006
Chapter/Region:
AKIC
Location: Oneonta, NY
Vehicle:2005 WRX STi WRB |
Maybe it's your gauge and or sensors or a exhaust leak... Check hose first... There is a tsb however on the output wire that feeds into the ecu from the alternator. Telling the ecu what voltage the alternator is charging the system at.. good luck! I went through this also. Ended up wiring my entire engine harness repairing high resistant ground wires... Along with finding a electrical drain on sb5 and tracing that back to the keyless entry system... LoL good effing luck broham...
Check all your ground wires. Along the radiator support... I also found bad terminal connections at the fuse junction box.. that I repaired with plyers by pinching the terminals. |
Thread Tools | |
Display Modes | |
|
|