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8 Posts
Discussion Starter · #1 · (Edited)
Hello guys,

I have some problems with my recently bought R33 GTR.
The car is quiet much modded:

HKS F-CON V Pro Ver3.1
HKS T45 Turbo + Manifold
HKS Super Suction Filter
Asnu 714cc Injectors
JUN Cam 272 10.5lift (seems in and ex?)
Greddey 1.2mm headgasket
Boost was set to 1.3bar and 1.5bar (lo/hi)
and a few more parts...

As i checked the engine i was figuring out that few original parts been not installed or disconnected.
For example, no lamda sensor, no MAF-Sensor, AAC-disconnected and so on.

It seems that when they installed the HKS F-CON they took out the original stuff.
What i found is that for replacement of the MAF-Sensor they installed the HKS pressure sensor which is a part of the HKS F-Con.

The problem i have:

The car has no cold start, which means revs too low when start up, I need to do the cold start manually by pushing the gas pedal.
As it warms up the rev stays most of the time at 900rpm but also sometimes drop down to under 500rpm which shuts the engine down.

Due to that i took of the AAC valve and cleaned it up completely.
But when i installed it and tested it, the idle was same or a bit higher like 1100rpm.
What i also found was that after reconnected the AAC (when i bought the car it was unplugged and it seems the plug was off form a long time as the plug was way dirty) that the car seems to run at the safety mode.
Till 3000rpm it runs ok but after its like kinda misfiring.

I'm wondering now if those things like MAF, Lambda and the AAc been unmount of unplugged how does the original ECU know when it has to use the cold start map and when the other one?
Because it seems the car takes quiet a lot of gasoline.

Could it be due to the HKS F-CON it's better to let the AAC valve unplugged?
Just wondering how you guys deal with it when you have a quit bigger engine modd done.

Any input or suggestion about the issue would be appreciated.

Premium Member
4,447 Posts
Not needing mafs is a positive

Your problems are almost certainly not because you have an fcon but because it has not been set up fully

As to mpg your set up isnt one that has economy as one of its features especially if it isnt running right.

8 Posts
Discussion Starter · #4 ·
Thanks for the reply guys.

On weekend i checked a bit the stuff and also reconnect the AAC Valve and adjust the idling as mentioned at the manual.

When start up, the car doesn't idle, i have to push the gas to let it idle for a while and then the idle get stay able around 1100rpm.

If i disconnect the AAC Valve plug, then the idle drops to around 900rpm, which means the valve itself should be working.

Could it be that the throttle position sensor is not right adjusted too?
Because it seems like it doesn't switch to the idle function.
I try to measure it out put couldn't get into the cable to grap a signal, need to try a again with a needle or something similar to get into the cable.

On the other side, it would be good to have a look at the F-Con maps as RSVFOUR mentioned it. Could be that the setup was not done right.

Problem is that in Korea are not many people who knows such stuff or better to say are licensed to work on a HKS F-Con.

But i think it make also no sense to "send" someone the ecu to have a look at it or?
I mean without the car to test it under real conditions it doesn't make much sense to me, or is it still possible to have a look at it?
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