I have a 2004 Silverado 5.3L and i just put a turbo on it. I had it tuned yesterday and everything was working great. I drove it to work this morning and it drove good. The idle was around 8-900 in drive and park. Started it after work and it was still good.

On my way home I pulled over at the grocery store, put it into park and the idle shot up to 1500rpm. I thought maybe the pcm just had a brain fart so i didnt think anything of it. After the store i started it and it had the same idle of around 1500 in park but when i put it into drive it went down to 8-900rpm. I started driving and i got a message on the dic saying SERVICE BRAKE BOOSTER. The message disappeared by the time i got home and i got an ses light. I scanned it and it was iac higher idle than expected.

Anyways, I check under the hood and this seems a little bit weird to me. On the back of the intake i see a little red thing that i've never seen before. I dont know if i just never noticed it before or what. But the fitting that the brake booster hose attaches to on the intake spins in the intake. Is that normal? My tuner said i probably have a vacuum leak somewhere so I'm thinking this is the source.

Can someone with an 03+ check the back of the intake to see if it looks like this? Yes i am aware that the clamp is off but i took that off when i was checking it out.

Thanks

 

seems as you pushed boost into the brake booster. is the one way valve still there?

 

Where would the one way valve be? I always wondered if people put check valves or anything into the brake hose but never found a clear answer..

 

mine is the fitting that goes in the booster

 

I will go check. Maybe thats the thing on the back of my intake.

 

This is what it looks like where the hose connects to the brake booster.


And heres a better pic of the back of the intake.


The red thing spins around and feels loose.

 

the red thing is supposed to be free. to release the vac line fitting there you push in on the line and then hold the red thing against the intake and pull on the line.

Its kind of like an air hose fitting, the red thing would be the collar of the air hose.

 

Ah okay makes sense.

Now i'm confused why the service brake booster message came up and the high idle. Any other ideas?

 

Been messing around with it today and still cant find whats wrong with it. Started it up and it was idling fine right at 8-900 rpm for about 5 minutes and then when it was up to operating temps the idle shot right back up to 1500. I also noticed that the idle speed increases 2-300 rpm if i pump the brakes. wtf is going on? When i put it into drive the rpm drops down to 8-900.

I sprayed the intake and everything down with brake cleaner and didnt find any leaks.

 

Did you spray the brake booster vac line and everything?