Is 10 lbs of vacuum too low?

[baller760]

Before I got the car smogged and all the smog equipment was put on it I usually had between 14-16 pounds of vacuum. After I now have about 6-7 lbs when idling in park and 10 when I let of the gas while driving. Is that normal? Shouldn't there be more?

Also, on a side note, the car is struggling to stay idling when I put it in drive. After it's been in drive and adjusts the car is fine but from park/reverse to drive it almost dies out and actually did die out the other day. I usually just give it a little gas to get the rpms up. What adjustment do I need to make?

 

[Quick6'n'-K.C.]

Check to see if you blew a line off somewhere.

Alot of times, the 7/32 hoses will blow off do to being dry rotted or a bad check valve blowing by.

Check all the hoses under the hood to see if they are tight, doubt the hose at the gauge inside the car is bad
BW

 

[baller760]

I checked most of those today and I got the vacuum to jump up to 9-10 pounds. Before it was at 6 at idle. I ziptied some hoses and replaced the PCV. They all seem fine and the hoses are all new anyway so I don't know what it could be.

 

[Quick6'n'-K.C.]

Make sure you didnt blow a intercooler hose slightly off, and double check all the hoses... Even the MAP sensor line at the pass side fender well.

BW

 

[baller760]

Well I didn't blow off an intercooler hose. I was thinking though. Since I just got the car running again not too long ago the shop did not set the cam sensor. So, maybe since it is not set the computer is acting like it's an aftermarket cam and therefore decreasing my vacuum pressure? If I got the casper's cam sensor cap and installed it do you think the pressure would rise a little?

 

[Quick6'n'-K.C.]

No.

Only if your car is currently ideling at 200 rpm.

Check all your vacuum hoses and what smog parts did you install to change the cars ability to run correctly?

BW

 

[baller760]

I installed an EGR, an evap canister, and a catalytic converter. I have ziptied down every hose I can find on everything. I even installed a new billet vacuum block today and ziptied the new hoses down on both ends. My vacuum is still around 9 lbs. I'm figuring it has to be a plenum leak maybe? The gasket could be broken I assume. I'm just getting really irritated now, where else can I look?

 

[quicker6]

Eliminate the possibilty of it being your vacuum gauge by using someone elses for a few seconds. If it still has the same result than check your compression. You could have a weak cylinder or something.
Good luck

 

[baller760]

Well, I don't think it would be that because before the smog equipment was put on the car had 15-16 lbs of vacuum and since then it has about 9.

 

[Mile Hi GN]

If you are sure the gauge is good, I would work backwards. Is the loss of vacuum something new or related to the install of the smog equipment?

Remove the evap canister back to the way it was - test. Remove the EGR - test.

My money is on the evap canister.

 

[QUIP'6']

what are your blm's if they are pegged at 160 you ahave a vacuum leak

 

[baller760]

Yup, it turned out to be a fitting on the evap canister. Now my vacuum while idling in drive is 12-12.5 lbs. When driving and when I let off the gas the vacuum ranges from 15-16 lbs. And my BLM's are high 150's but when I give gas in the 11X's.

 

[flattype]

If you are sure the gauge is good, I would work backwards. Is the loss of vacuum something new or related to the install of the smog equipment?

Remove the evap canister back to the way it was - test. Remove the EGR - test.

My money is on the evap canister.

You mean the hoses going to it or the whole evap canister can cause a vacuum leak? (Im chasing down this same problem thanks) Can I just plug off the vacuum to it if its bad?

 

[JDSfastGN]

still seems like low vacuum for a stock cam setup. I would double check that the EGR is sealing as well as the solenoid (can leak internally) The EGR can be a pain to seal for some reason.

 

[baller760]

Well if I remember correctly the vacuum was about 12-13 inches in park before the smog equipment was put on and that's where it is now. When I put it in drive the vacuum goes down to 10 inches or so. When I am driving and let of the gas it rises to 15 inches. I don't know where else there could be a vacuum leak, I have literally checked everywhere thousands of times.

 

[Gary Wells]

Well if I remember correctly the vacuum was about 12-13 inches in park before the smog equipment was put on and that's where it is now. When I put it in drive the vacuum goes down to 10 inches or so. When I am driving and let of the gas it rises to 15 inches. I don't know where else there could be a vacuum leak, I have literally checked everywhere thousands of times.

------------------------------
Still sounds a little low to me.

 

[carrddine]

What is considered low? where should vaccum be? in drive and car fully warmed up?

 

[Marc87GN]

You mean the hoses going to it or the whole evap canister can cause a vacuum leak? (Im chasing down this same problem thanks) Can I just plug off the vacuum to it if its bad?

I think they are talking about the hose to the valve. Probably the purge valve. The line to the canister comes from the tank if I remember correctly. I had a vacuum leak and the first thing I did was remove the block and block it completely and worked backwards from there. That should eliminate everything else.

 

[Gary Wells]

When first fired up & running in idle, about 1K RPM or so, seems to hold about 18"-19" pretty steady, and when almost warmed up and idling about 750 to 800 RPM or so pulls about 17"-18" vacuum. I will take a closer look Sat morn. Cammed cars generally hold a little less vacuum.

 

[Marc87GN]

When first fired up & running in idle, about 1K RPM or so, seems to hold about 18"-19" pretty steady, and when almost warmed up and idling about 750 to 800 RPM or so pulls about 17"-18" vacuum. I will take a closer look Sat morn. Cammed cars generally hold a little less vacuum.

My car does the same thing actually and holds about 16-17 in gear at idle.

I had a problem where the idle, on cold start, would sound almost like it was missing, while the rpms were coming down from fast idle. I figured since I run CAI that some of the oil was sucked up and stuck to the elements in the MAF. It's not something that easily shows up on a scantool (maybe directscan it might). I took some INTAKE (not Carb) air cleaner and blew probably 1/4 of a can through the intake at the MAF while the car was running to the point of stalling the car. The car has started ever since with a very smooth idle.