RB26 issues

[terry_valley]

RB26 issues

Good Afternoon everyone,

I've finally had time to start repairing my GTR. I had a vacuum leak from the intake manifold in the past and have changed all gaskets. Since putting it back together, two issues exist:

I've lost the brake booster
I have a fluctuating idle...When I start the car, it idles and sits at 2000rpm for about 10 seconds, following that it idles between 1300rpm-2000rpm (fluctuates)

I have taken the car to a mechanic and they have tested for leaks with a smoke machine. No leaks were reported.

Does anyone have any experience with these issues or have any ideas as to where I should start?

 

Thank you, comments much appreciated! 

[r32-25t]

Did you clean the throttle bodies when you had them off?

[GTSBoy]

Brake booster sources its vacuum from the auxiliary plenum that runs under the manifold runners.  Like.....after the throttles.  If the smokers didn't open the throttle, then no smoke will reach the leak.

[R.3.2.G.T.R]

brake booster also has a one way valve iirc, yours still installed?

[terry_valley]

Thanks for the answers! I didn't clean the throttle bodies I read about not cleaning them as they have a seal. I will check the brake booster hose as I don't believe they opened the throttle bodies in smoke testing!

[r32-25t]

Check the plastic chamber near the guard that the hoses for the booster go to isn't cracked 

[terry_valley]

Hey guys, I've checked to see if the IIRC valve is operating which it seems to be, the plastic chamber is not cracked... I've checked the hoses out of the auxillary valve and they seem to be on tight and in the right location. (I also installed new hoses) Does anyone have any other suggestions as to why the brake booster is not working and a fluctuating idle? Thank you so much in advance 

[Sinista32]

Potential to be 2 seperate issues with many causes. Here's some

Brake booster: Air in the brake system, booster flange issue, one way valve, vacuum leak/air leak

Eratic idle/Idles high: Vacuum leak, fouled Injectors, Idle speed, fouled plugs, ECU setting/s

[terry_valley]

guys just for an update I've fixed the brake booster issue, the idle now sits at 2100rpm when it starts then hunts between 1500rpm-2100rpm...Could it be an AAC issue? or can anyone else point me in the right direction? 

I've driven the car and it drives fine, it's just that idle issue now.

Thanks so much in advance

[GTSBoy]

Vacuum leak still there.

[terry_valley]

On 2/17/2017 at 4:34 PM, GTSBoy said:

Vacuum leak still there.

If there is one it's hidden away better than the Nazi gold train, Searched all weekend for it, put a new gasket on the AAC valve and cleaned it, same result