sometimes into vacuum sometimes not

[SpoolinTalon2]

my boost gauge, at idle, sometimes goes into vacuum and sometimes it doesn't. when i drive the car it goes into vacuum and when i park it it stays in vacuum until i turn the car off. also, it goes around 12 into vacuum at idle and around 15 into vacuum at boost, just checking to see if these are normal number? i have been looking for a boost leak but cant find one, but will keep looking. is it possible that the home made catch can that i put in affects this? i put the pvc hose into the can and put a breather on top of the can and a breather on the nipple of the intake pipe. some advice would be great before this weekend so i can fix this. thanks.

 

[streetlegends]

Are you getting any bad idles?? If you don't have it sealed then it's possible but if you want to see if you have a leak anywhere this is what you can do, get so liquid soap carwash, dishwashing liquid,and etc with some water not alot. Take it and put over areas where it could be possibily leak from and start up the car and if you see bubbles you have a leak in that area but don't stop there check all over because it could be in more then just one area. The other way is the see if you hear a hissing sound. Good luck on findind the problem(s).

 

[No_Skillz]

You might also want to check how your boost guage is connected. If I remember clearly one of the options is a solenoid which only goes into vac once the engine is warmed up.

 

[steve]

If I remember clearly one of the options is a solenoid which only goes into vac once the engine is warmed up.

Close, the FPR Solenoid is used for hot starts. When the engine is hot the ECU activates it to disconnect manifold vacuum from the FPR to raise the fuel pressure and fight vapor lock.

Your correct that if the boost gauge is connected after the solenoid rather then before, it might not see vacuum at first.

Steve

 

[SpoolinTalon2]

i believe my boost gauge is taped into the hose that connects to the intake manifold and solenoid. i dont know if that is before or after the solenoid, what is the correct way? thanks.

 

[steve]

what is the correct way? thanks.

Before the solenoid, so it sees what the manifold pressure/vacuum is all the time.

Steve

 

[SpoolinTalon2]

how do i know if it is before the solenoid? is this a pic of what it should look like?
http://www.roadraceengineering.com/instructions/vdoboost/vdoinstall-2gteefitting.jpg
thanks

 

[steve]

how do i know if it is before the solenoid?

Well, I'd grab the hose as it comes off the intake manifold and follow it to the FPR solenoid. If you find the tee for the boost gauge before you hit the solenoid it's before.

Steve

 

[SpoolinTalon2]

i think i do have mine teed in with the hose that connects the solenoid and the intake manifold, but i will double later since im not by my car right now. if it is connected right, do you think it will be a boost leak then? also my vacuum hose goes around the whole hole of the boost gauge, not into it. for example a tube that is going around the whole other tube, not into it. do you think this effects anything b/c of the size of the hose? thanks.