Is this a vacuum leak?

[ByrdClaw]

When I first start my car in the morning, My idle tends to bounce up and down,and if I watch my boost gauge the vacuum goes from 20hg to around 12 hg and back to 20. Once warm it idles perfect. Any suggestions?

 

[BoostedTalonTS]

it could be, but I would start by making sure that your BISS is adjusted correctly & that your ISC is centered in it's adjustment range once the car is fully warmed up.

Do you have a logger?

 

[Bluefire16]

^^ The biss like already stated would most likely be the possibility. But be easy on it, its very temperamental. Also just check for some boost leaks, you might have some very small ones.

Lastly, my car does this once and a while.... its kind of "normal." When i start my car it was be between 15-20 but once it settles a few minutes its always at 20-21. If this is what your car is doing im sure your fine.

 

[smprende10]

the reason the inHg is bouncing around is because your motor is not settled at a steady idle... but a vacuum leak or boost leak is most likely like you said.

 

[ByrdClaw]

I do have link,and my wideband is reading 16+ at idle. Would an exhaust leak also cause this? My idle after warm sits at like 2000 rpms,I have never adjusted the biss. How do I check my ISC with link?

Also I set my idle at 900 with link,but maybe I didnt save it to the ecu.

 

[9!'clipseDOHC]

Your idle should be set at 750 +/- 100, anything higher or lower then that will be out side the range of the ISC. I'm on my phone so I can't post the link but search DSM ISC on youtube for a video of how to test your ISC.

Hope this helps!

 

[bigbird]

Most cars hit a fuel cut at about 2500 rpms when the throttle plate is closed. This can be a vacuum leak, failed idle air control system or a poorly adjusted idle.

 

[ByrdClaw]

I grounded the timing connector through dsmlink to adjust the biss,and When i grounded it and adjusted the biss properly it was fine. As soon as I unground it the idle jumps back up to 2000 rpms again. Am I suppose to leave it grounded?

 

[9!'clipseDOHC]

Try grounding it manually. There are 2 connections that need to be grounded to properly set the idle. Here is the proper way to set your idle: 1G BISS Adjustment.

Hope this helps!