Low Vacuum

zer099

Member
Okay, so I'm not too worried about this but it has been bothering me. I rebuilt my turbo and ever since the vacuum at idel has been at about 16in/Hg. She boosts, pulls, and idles just fine. I've pressurized the system and there seems to be no boost leaks. I can't figure out what seems to be up. Before the rebuild she sat around 18ish in/Hg at idle.

Anyone have any ideas to what is up and if I should be worried? Thanks ahead of time.

Oh, and btw, I did search and didn't find much other then people saying check for boost leaks, which I have. I did find that one guy did say that his sat at about 16in/Hg as well and he never had a problem. Thanks!
 

zer099

Member
If it seems right to everyone then I'm not worried at all. It was just something I noticed and thoguht I would ask about. Thanks!
 

youngsyp

New Member
Mine sits at between 900 and 920 rpm at idle and I checked the vacuum today. It was between 18 and 20 in/mg.

That's with all the EGR system removed and left over pipes plugged. The breather system simplified and all vac points bunged and a freshly sealed inlet manifold and plenum.

Paul
 

zer099

Member
Yeah, see that's what mine use to be. Now she starts at 14ish inHg and warms up to 16inHg and holds there. Under engine slow down she goes to about 22inHG, like she did before. Everything infacts feels like she did before except that she now sits at 16inHg.

Anyone know what else could cause low vacuum other then a boost leak? Or cams... 'cause I do not recall putting cams in her.
 

youngsyp

New Member
zer099 said:
Yeah, see that's what mine use to be. Now she starts at 14ish inHg and warms up to 16inHg and holds there. Under engine slow down she goes to about 22inHG, like she did before. Everything infacts feels like she did before except that she now sits at 16inHg.

Anyone know what else could cause low vacuum other then a boost leak? Or cams... 'cause I do not recall putting cams in her.
Any type of vacuum leak could also affect the vacuum figure.

As will engine/idle speed etc...
Paul
 

zer099

Member
Well, there is no leaks under preasure. I've pressure checked her like 100 times. She's solid. I guess I can make a leak down tester and apply vacuum to her and see if she leaks. Might do that tomorrow.

She idles perfect, like before. Thats the thing, nothing is actully wrong. Fuel mileage, idle, boost, everything is the exact same except the vacuum during idle. That's why it's not bothering me much, but it still is on my mind. Know what I mean?
 

youngsyp

New Member
zer099 said:
Well, there is no leaks under preasure. I've pressure checked her like 100 times. She's solid. I guess I can make a leak down tester and apply vacuum to her and see if she leaks. Might do that tomorrow.

She idles perfect, like before. Thats the thing, nothing is actully wrong. Fuel mileage, idle, boost, everything is the exact same except the vacuum during idle. That's why it's not bothering me much, but it still is on my mind. Know what I mean?
If it's not bothering you, just forget about it. It doesn't sound like anything's wrong to me. Most likely just fluctuations in the gauge accuracy...

Paul
 
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