I have an 03' G35 coupe. Today, it suddenly started suddenly running crappy.

For starters, the car will not idle on it's own. If you start it and play with the gas, you can eventually get it to run. Once it's in the upper RPM range,it will run, and seems ok. However, as soon as you let of the gas, the RPMs drop and the car will die. It will restart every time, just wont idle.

While driving, the car doesn't seem down on power. It will pull just fine at WOT, and seems to run ok as long as you're in the upper RPM range. It's not smoking, and mechanically everything seems ok.

There are NO check engine lights. There was a stored misfire code, which is to be expected seeing as the car runs like *** at idle. Otherwise the codes are clean.

Searching around didn't really yield much help. I tried all the relearn procedures here: http://www.nicoclub.com/archives/g35...-learning.html . None of them helped.

I'm looking for suggestions. I would assume if the throttle body was ****, it would throw a code. Maybe not? Any help would be greatly appreciated.

-Brett

 

well check spark plug and fuel injectors for starters. is your car stock?

 

The car is stock aside from an HKS intake and exhaust.

 

Sounds like you might need to clean out the MAF (mass air flow) sensor and the throttle body.

 

How long ago was the intake and exhaust installed?

 

Ding ding ding
Winner.

 

Start with the MAF and check that intake filter, HKS needs to be cleaned frequently...Gary

 

The car only has about 85k miles on it. I've had the intake and exhaust installed for probably 15k.

I removed the air filter completely and started the car to see if that did anything, and got no change. I did some research, and cleaning the MAF should be easy. That will be my next step.

For the throttle body, I'm finding conflicting information on cleaning it. A lot of people say not to, some say it's fine. Is there a good how-to or something somebody can like me to? Any info or advice on this?

The car ran perfect 2 days ago,and now runs like complete a$$. Would a bad MAF or TB not throw a code?

 

May be random but, what kind of gas did you put in your tank last?

 

Sounds like the MAF or the Throttle Position

 

Ok guys. First, let me say thanks for the suggestions!

I think I figured out the problem. So, the foam filter for the HKS intake system seems to be deteriorating a bit on the inside. As a result, some little pieces of the foam got sucked into the intake, and also into the MAF. I could literally see little foam pieces inside of the MAF where the sensor wires are located:



So, I just blew the sensor out with compressed air and reinstalled it. I started the car (air filter removed) and it fired right up and seems to be running perfect. Seems like the issue is gone. I ordered a new filter element, so I can't really drive the car until it gets here. I'll report back and confirm the issue is fixed.

Thanks again for all the help, guys.

 

HKS has major issues with quality control and never admits their products are anything but perfection! Best advice, replace the HKS intake with Stillen's CAI which comes with a large K&N cone filter...Gary

 

Installed a new filter, and cleaned the MAF with CRC mass airflow sensor cleaner. The car is running great now.

Thanks for the help, guys.