hello! I have a 2008 AT g37s coupe.
My current mods are: Stillen G3 Intakes,Stillen exhaust,and cobb tuen, going to put the test pipe on it next week.

but now, after i put the intake on it , and change the map to the stage 2 with cobb, my rpm become so crazy,sometime goes up to almost 2000, or drop to like between 500-600 .when i step on the gas, it doesn't really response , i step deeper, the acceleration goes up suddenly,or goes up and down, that was so scare!! and also, i got Check Engine Light p0174 system to lean bank2. is it the problem on the tune? what do i need to do? if I use uprev tune, will it give me back my power?

i checked, no leak on the intake, I really want to keep the intake, plz help me, is it something wrong w/ the tune? I tried to uninstall the tune , but it doesn't work, and the rpm even drop more to about 500, the car was shaking!!

nothing wrong w/ the exhaust and the air sensor .

the problem appeared when I install the intake. new tune or any idea?

 

I would take it for a check up definitely. Sounds similar to what happened to this guy I know. His G was working fine, but as he wanted to accelerate the car wouldn't give him any power. It started working fine for a couple of minutes before it got worse. When they took it to the garage and got it checked out, they found that the transmission was ripped to shreds. The dealership even flew in a guy to investigate exactly what happened, and he said he never saw anything like it.

Let's hope your problem isn't this, but I'd definitely get it checked out.

 

P0174 Fuel injection system (Bank 2) too lean

With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the theoretical mixture ratio based on the mixture ratio feedback signal from the heated oxygen sensors 1. The ECM calculates the necessary compensation to correct the offset between the actual and the theoretical ratios.

In case the amount of the compensation value is extremely large (The actual mixture ratio is too lean.), the ECM judges the condition as the fuel injection system malfunction and light up the MIL (2 trip detection logic).

DTC detecting condition:

* Fuel injection system does not operate properly.
* The amount of mixture ratio compensation is too large. (The mixture ratio is too lean.)

Possible cause: (All in Bank 2)

* Intake air leaks
* Front Heated oxygen sensor may be faulty
* Injectors may be faulty
* Exhaust gas leaks
* Incorrect fuel pressure
* Lack of fuel
* Mass air flow sensor may be faulty
* Incorrect PCV hose connection

 

wow!!!!!!!! you mean if i have the some problem, i have to change the transmission?!

I m going to do those step:

1. clean the mass air flow , if works, thanks god!
2. change back to stock intake, and see what happen.

if the problem is from intake itself, i need a new tune?

I was wondering, if you have intake and exhaust, then you have to tune your car?!

 

Go back to stock intakes, see if it happens again. Many of us have intake+exhaust but no leaning error code.

If it goes away on stock, maybe it's the gen 3 + all your mods. I've heard the gen 3 to cause leaning before on someone else's car.
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Yeah, well that's what the did for him. They replaced the 5AT set on his 08 G37 with another 5AT (he tried getting a 7AT).

But like nogoodname said P0174 has to do with the fuel injection system.

Keep us updated on the issue.

 

just clean the MAF, it seems back to normal. i think the K&H oil fitter cuase the problem. i will go test drive today n we will see what happen.

if the problem solve, the other problem is intake+exhuast+COBB in stage 2, i feel that the car is losing power, it doesn't really accelerate in lower rpm, when i step more gas, it kind of slow and have to think, then power up. it did accelerate after 5000 rpm. normal?!

 

Every body is quick to blame the car when 99% of the time time it's user error...and 100% with mods. Oil on the MAF is a common issue.

 

there is no way to have a intake and exhaust, if u dont have a good tune, i died on high way today, really scare... i change back to stock intake, and everything back to normal..thank god. but it doesnt really accelerate when i step on the gas. this time, i think the problem in the cobb tune, i m gonna uninstall it, and see what happen.

 

problem have been solve!! bad air sensor!!!!, change to the new one, the car back to normal.!!

 

PHEW! Good to hear it was nothing more than an air sensor