Nissan throttle bodies are notorious for getting dirty pretty quickly. If your car has a rough idle, it is probably a dirty TB.

Here's a link to the issue I had before doing this-
https://g35driver.com/forums/v36-eng...-rpm-drop.html

Items Required:
- 8mm socket wrench
- 10mm socket wrench
- 5mm allen key
- Clean shop towel
- Throttle body cleaner
- Pliers (optional)
- 2x throttle body o-ring seal (optional)

You will need to have the engine cool down before you start working. First you'll need to remove the engine cover. If you have a FSB like me, you'll need to remove that first. Simply take off the aluminum bar with the required allen key.




Next you'll need to remove both intakes to access the throttle bodies. It is best to clean one TB at a time. Removing the intakes will depend on what type you have installed.



Once you have removed your intake, you can see the TB and the butterfly valve inside (golden). You shouldn't see much dirt yet, as most of it loads up behind the valve. To take off the TB, you'll need to remove four hex bolts as shown below with a 5mm allen key. use the star configuration when removing and installing these bolts. They will be tight since they have thread lock applied to them.



Once you have removed these bolts, take care when pulling off the TB since there is an o-ring seal on the plenum.
The TB will also have a connector for the throttle position sensor as well as two coolant tubes connected to it.
Do not disconnect the harness connector or any of the tubes.
You should have enough space to work with.



You can see all the dirt on the other side of the TB. It is really sticky tar and will need some nice scrubbing with a towel and a TB cleaner to remove it.



There will also be some carbon/tar deposits on the plenum side as shown below. It is the greyish stuff on the lower portion.



To clean the TB, spray some of that TB cleaner (you can also use a very mild degreaser) on a clean towel. Push the butterfly valve to access all the necessary areas and start scrubbing it off. Once that is done, it should look good as new. Below is what mine looked like after cleaning. I also did the same for the plenum. Do not spray the cleaner into the plenum!



If your car has seen a lot of miles, it is a good time to replace the o-ring seal between the TB and the plenum.

Once the TB is clean you can now reinstall everything in reverse order. Repeat the same process for the second TB.

Note: You may need to drive around for a couple days so that the ECU has time to learn the idle position.

I will not be held responsible if you mess up your TB's or engine in any way. Perform this procedure at your own risk.

Edit: Made a video of the process below


Hope that helps

 

sweet! hey, how many miles does your G have?

 

So far I have 26K miles, but my idle started acting up since 10K miles.

 

:EDIT: to OP
Do not disconnect the harness connector!
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Great DIY Q8y_drifter
I took the liberty to add this^ edit to your post.

It's very important to NOT disconnect the harness.
If it is disconnected, and the butterfly is moved while cleaning;
the ECU will lose the closed or zero position of the sensor.
If that happens the car may not start or may run poorly.

If the cable is disconnected you have to perform a
"THROTTLE VALVE CLOSED POSITION LEARNING" procedure for the ECU.

 

this is a great DIY.
Thx.

 

InTgr8r, I thought I mentioned that already? must of forgot lol

Thanks

 

You know until now (touch wood) I haven't faced any fluctuating idle problems, is this because I haven't changed my airfilter?

I'm thinking all the guys that are having this problem is due to installing aftermarket filters? Maybe I'm wrong but my idle is perfectly level last time I checked.

On my Audi I did have to do this cleaning process every now and then, due to dirt coming in from my aftermarket filter, but not yet on the G35.

does anyone have fluctuating idle problems with the oem filters?

 

everyone had it with OEM filters (including me). When I got it my car was stock.

The carbon deposits have nothing to do with the filter or intake anyway. It comes from the crankcase ventilation system. The carbon goes from the crankcase to the intake tube through the little tube connected between the intake and engine block. then it builds up at the throttle body behind the butterfly valve. When the valve is only slightly open (at idle), the deposits block the air that is supposed to go through, this causes the RPM to decrease and the engine almost stall (hence you get the car shivers as I mentioned in my old thread), the ECU therefore opens up the butterfly valve a little more so the air can go through, this causes the RPM to rise up. This is basically what causes the fluctuating idle.

 

Ahh I see, ok my bad I thought it was just cr@p that got in because of the filters being replaced .

BTW how many miles/kilos has your car done?

 

.............

 

Had to chime in and let you know, GREAT DIY!

 

good write...time to do mine now..I just corssed 40k miles

 

Nice DIY doing mine this weekend... if weather permits

 

Great DIY and timely, too... I've got close to 45K and never cleaned my TBs, run stock intake and filters - idling has been rough for a while.

 

Great DIY 8qy. Thanks for posting that up. I used the same procedure with my 1st gen coupe along with a soft toothbrush to get at the difficult places.