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Old 03-07-2021, 07:40 PM   #1
yliu14
Scooby Newbie
 
Member#: 522835
Join Date: Mar 2021
Location: New Zealand
Vehicle:
1998 Impreza WRX STI
White

Default JDM v5 STI ECU questions.

Recently I bought a JDM GC8 v5 STI, it’s running weird.
When cruising around 2-4K rpm and give throttle slightly, it has no response, sometimes even losing power. When depress more of throttle, it will suddenly “kick” me with quickly rising RPM. (Not boost up)

It has brand new OEM AFM, factory ECU, but a TD04L turbo(should be VF28).

Any suggestion will be appreciated.
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Old 03-08-2021, 02:34 AM   #2
alexmartynyuk
Scooby Specialist
 
Member#: 191967
Join Date: Oct 2008
Location: Vancouver
Vehicle:
2005 EVO VIII
open source tuning subaru

Default

Quote:
Originally Posted by yliu14 View Post
Recently I bought a JDM GC8 v5 STI, it’s running weird.
When cruising around 2-4K rpm and give throttle slightly, it has no response, sometimes even losing power. When depress more of throttle, it will suddenly “kick” me with quickly rising RPM. (Not boost up)

It has brand new OEM AFM, factory ECU, but a TD04L turbo(should be VF28).

Any suggestion will be appreciated.
Do you have any datalogs?
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Old 04-04-2021, 12:35 PM   #3
subaru_gc8
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Member#: 29292
Join Date: Nov 2002
Chapter/Region: SCIC
Location: Orange County CA
Vehicle:
2004 WRX wagon
silver

Default

Quote:
Originally Posted by yliu14 View Post
Recently I bought a JDM GC8 v5 STI, it's running weird.
When cruising around 2-4K rpm and give throttle slightly, it has no response, sometimes even losing power. When depress more of throttle, it will suddenly "kick" me with quickly rising RPM. (Not boost up)

It has brand new OEM AFM, factory ECU, but a TD04L turbo(should be VF28).

Any suggestion will be appreciated.
check your coil and wires sounds like a misfire to me
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Old 05-29-2021, 04:52 PM   #4
yliu14
Scooby Newbie
 
Member#: 522835
Join Date: Mar 2021
Location: New Zealand
Vehicle:
1998 Impreza WRX STI
White

Default

Quote:
Originally Posted by yliu14 View Post
Recently I bought a JDM GC8 v5 STI, it’s running weird.
When cruising around 2-4K rpm and give throttle slightly, it has no response, sometimes even losing power. When depress more of throttle, it will suddenly “kick” me with quickly rising RPM. (Not boost up)

It has brand new OEM AFM, factory ECU, but a TD04L turbo(should be VF28).

Any suggestion will be appreciated.


Problem solved. For somebody who may experiencing the same issue:

It’s the air fuel ratio issue. Due to its running rich, the O2 sensor becomes very dirty when I took it off and it’s not OEM as well. I soaked it into gasoline overnight and put it back on, all the “jerk” gone. Since I know it’s the O2 sensor issue, I bought brand new OEM sensor and installed, running perfect and feels more power.
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