Vacuum keeps getting close to 0

**Exanimas** · 12-05-2008 09:31 PM

So, dumb question - I can't remember exactly, but I feel like when I first got my boost gauge I would idle at like -18 or so. Then after I installed new plugs (which coincided with the weather getting drastically colder) it seemed to go down to about -15 or -16. On my way home tonight I was stopped at a red light and noticed it was flickering between -12 and -13. Any idea what's going on? Is it a vacuum leak, bad plugs, or could it just be the cold weather? Any help is greatly appreciated.

**[email protected]** · 12-05-2008 09:41 PM

You have a vacuum leak somewhere.

I'd check the hoses as the cold temp could be making them crack open more.

**Exanimas** · 12-05-2008 09:43 PM

I probably should've posted this in the original, but when I coast I still get a consistent -22. Does that change anything or still sound like a vacuum leak?

I'm just hoping it isn't because I'm so, let's say mechanically challenged, that I would probably never find the leak.

**[email protected]** · 12-05-2008 09:45 PM

If you are not around -18 to -22mmHg at idle then you have a leak somewhere

**Exanimas** · 12-05-2008 09:47 PM

Damn, well thank you for the help Winston. Is looking for a vacuum leak anything like looking for a boost leak? Or should I just give the hoses a visual inspection?

**[email protected]** · 12-05-2008 09:51 PM

Not the greatest diagnostic method but if you smoke it makes things a bit easier... take a puff and blow the smoke in the engine bay and see if any of the hoses suck in the smoke.

But I'd check all of these hoses for cracks and valves to see if they may have separated/cracked.

It's not fun work but it is something that should be done routinely.

**9744RR** · 12-06-2008 09:56 AM

If you suspect a vac leak, get some brake cleaner and spray around the vac hoses and check valves, If the idle changes, you found the leak.

**AudiA4Turbo22** · 12-06-2008 10:16 AM

i can't figure it out for my car as well i've checked almost every line changed every check valve much of the vac lines as well in park i get -14

**Exanimas** · 12-06-2008 10:19 AM

Originally Posted by 9744RR

If you suspect a vac leak, get some brake cleaner and spray around the vac hoses and check valves, If the idle changes, you found the leak.

Interesting. Although it wouldn't necessarily help me determine exactly where the leak was, thanks for the tip.

And Kirk, I don't think the vacuum is as strong when my car is in park, but the second I put it in D it gets lower. I'll confirm on my way to work today.