Over fueling under load (Boost)

MrMann

Idling at the Lights
Premium Member
Location
New Zealand, Southland
First Name
Johno
Drive
1997 Legnum - Non Turbo 6A13 - just hit 200,000KMS! 15,000 since ownership
1998 Super VR4 - Living on jackstands... for now.
It's been awhile since I've posted about my Super VR4, pretty much has the same issue since the day I've bought it.
What's been replaced, fuel filter+pump, leads, spark plugs, coil packs, multiple MAFs.
I put my foot down and above 3500rpm it dumps out black smoke over fuels and doesn't really boost. It used to lurch that turned out to be because of a boost leak doesn't do it anymore just over fuels to hell under Wide Open Throttle.
I can provide evo-scan logs no problem if someone is willing to compare.
Soon I'll be coming into my third Legnum that has rod knock but a complete stock 6A13TT engine.
So I'll be comparing against that/can use it to swap parts that might be causing my issues. It won't come with a transmission but that's fine.

Cars sure are pain, and she's a money pit coming on 2 years, but it's all learning and figuring it out.

Where should I be looking next? O2 Sensor, Fuel Pressure Regulator, Fuel Injectors?
 

BCX

Administrator
Moderator
Location
SA
First Name
Bill
Drive
2000 Galant Type-V
1997 MK Triton GLS [6G74 conversion]
2019 i30 N-Line
Maybe check wastegates are functioning correctly and turbos can spin freely.
 

MrMann

Idling at the Lights
Premium Member
Location
New Zealand, Southland
First Name
Johno
Drive
1997 Legnum - Non Turbo 6A13 - just hit 200,000KMS! 15,000 since ownership
1998 Super VR4 - Living on jackstands... for now.
hi i am having the same issue , did you sort out the problem ?
Sadly no I haven't found the problem.
I've boost leak tested as well and found no leaks.
I'd like to change the O2 sensor and I have some second hand injectors to swap in next.
I'm looking at using a Link ECU with this LINK ECU 6A1 Interface. Putting in a full aftermarket system with 4 Bar Map sensor, Intake Air Temp Sensor and Lambda sensor all interfacing with the Link ECU. Doing this so we can tune the car to not overfuel on boost. Because as far as I can tell so far it runs and drives fine the engine is healthy too and has been compression tested.
Doing this is really expensive and potentially I could be tuning an engine not running correctly leading to more broken parts and more expense.
Given how expensive it is and this doesn't even guarantee that the problem will be fixed I don't know if I'll do it.
If you do figure it out post your findings.
 

Baba Galant

1 AYC Bar
Lifetime Member
Location
Melbourne
First Name
John
Drive
Galant VR4 twin turbo 1997
You haven't changed the O2 sensor? This would be one of the first items of concern followed by fuel pressure regulator and injectors. Any ideas on your fuel usage?
 

MrMann

Idling at the Lights
Premium Member
Location
New Zealand, Southland
First Name
Johno
Drive
1997 Legnum - Non Turbo 6A13 - just hit 200,000KMS! 15,000 since ownership
1998 Super VR4 - Living on jackstands... for now.
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