Possible vacuum leak w/Whipple 150MM throttle body

[Wings65288]

Hi there guys, trying to chase down a possible vacuum leak. Just got the Gen5 3.0 Whipple on and car wants to idle at 2,000 RPMs. I unhooked the line that goes into the FRPS and backfed the smoke via that way. Other than coming out of the CAI filter the only other place the smoke came out was at the throttle body mechanicism area. See vid here, any ideas? Could the boost bypass actuator cause a high idle like this? Thanks!

 

[ITSTOCK]

Hard to tell from the video, but with that minimal amount of a leak right there, it's not the issue.

How did you originally set the throttle body for the tune?

 

[03terminatorcobra]

quite a few tuners and installers are recommending to not use the provided gasket for the whipple throttle bodies. instead, use a small bead of black RTV. im not sure if this is your problem but others who were having the same issue reported the high idle of ~2000.

 

[Wings65288]

Hard to tell from the video, but with that minimal amount of a leak right there, it's not the issue.

How did you originally set the throttle body for the tune?

Ok right on, I don't know what could cause such a high idle. It's actually more at a steady 2,500 RPMs at idle. The TPS is set to 0.755 volts. I have the stop screw on the throttle body backed all the way off too.

The smoke test showed no smoke in between the throttle body and inlet so I figured the gasket was doing it's job. I may try RTV if I can't find anything obvious.

Would a bad boost bypass actuator cause a high idle?

 

[olympic]

The bypass valve has nothing to do with idle because it just equalizes the pressure before and after the blower when it's open.

Quite a bit of fresh air is leaking into the engine somewhere for it to idle at 2500. Does the car still have the PCV system? Maybe the hose to the lower intake came unplugged. You could also try spraying some brake cleaner or starting fluid around the TB and intake gaskets to try and find the leak.

 

[Wings65288]

The bypass valve has nothing to do with idle because it just equalizes the pressure before and after the blower when it's open.

Quite a bit of fresh air is leaking into the engine somewhere for it to idle at 2500. Does the car still have the PCV system? Maybe the hose to the lower intake came unplugged. You could also try spraying some brake cleaner or starting fluid around the TB and intake gaskets to try and find the leak.

Good suggestion but I capped the PCV a long time ago. Yeah when I did the smoke test there was no smoke coming from the TB gasket. You think I should try RTV'ing it anyway?

 

[olympic]

It's worth a shot if others have had problems with the gasket as 03terminatorcobra stated.

 

[04torchred]

Hard to tell from the video, but with that minimal amount of a leak right there, it's not the issue.

How did you originally set the throttle body for the tune?

I agree here, have you adjusted the idle screw at all for the TB? I had to adjust my VMP big TB when I first installed mine on my 3.4.

if you unplug the IAC will the car start and stay idling? If so it’s getting way too much air through the blade.

 

[Wings65288]

I agree here, have you adjusted the idle screw at all for the TB? I had to adjust my VMP big TB when I first installed mine on my 3.4.

if you unplug the IAC will the car start and stay idling? If so it’s getting way too much air through the blade.

Yeah it'll stay running if the IAC is unplugged. My tuner had me do a pretty cool test using playdough. He had me unplug my MAF and plug the IAC in while the car was running. Then I removed the intake tubing to have the throttle body exposed. Then he had me start putting playdough around the blades. Once BOTH of the inner sides of the throttle body were covered it died instantly (confirming the throttle body was the culprit).