is this normal?

[Adam Hume]

just installed a boost gauge, it will move up to 14 psi, and then when i shift, it shoots up to like 18psi. This is pretty much stock engine except k&n, mbc, and free mods???

[James Coutu]

i lknow mine doesnt do that

[Jeremy Clarke]

Will it stay at 18?

If it just shoots to 18 momentarily it is called a boost spike and is often caused by the mbc or other various problems. If you do a search for boost spike you will find what you need to know.

[mike griffin]

14psi stock? or with the mbc i gave you? if its in, try taking it out and see what happens, and check your wastegate actuator hose.

[John Hartman]

just after you get back on the gas  it does that?

if so, yep, boost spike.  Fairly common.  its a function of several things, that like stated above, if you search you will find answers.  Some are free/cheap(shorter mbc hoses) and some are expensive but worth it.

[Adam Hume]

yea with the mbc you gave me...and it when i let off it will jump..

[mike griffin]

full throttle? part throttle? try taking out it out, and seeing if it spikes still. Try experimenting by turning it down a little too. My car did that when i first borrowed a friends boost gauge. I didnt even have a mbc, and i was running 10psi, and it would spike to 13 when i hammered on it and let off the gas. Then i changed some vacuum hoses and took out the BCS and it went away. Did you take out the BCS and plug the nipple coming out of the aircan like me and John said?

[Jeremy Clarke]

When you let off it will jump :shock:

Is your BOV connected? Is your boost guage on the right source?
I've never heard of boost going up when you get OFF the throttle :?

[Neil Fowlie]

I always though boost spike occured when you really floor it
and as the boost builds it will overshoot your set boost limit for a split second, then settle back down.

his boost is going up 4spi whenever he takes his off the gas
i think something is messed up with his gauge,

[John Hartman]

check what Jeremy said.  Especially check that your bov is correctly attached to the vacuum source.  Thats the only thing that I could think of that would show up as a raise in manifold pressure if you lift.

Also make sure you have correctly plumbed in your boost gauge.  If you get it on the wrong hose over there, or even on the wrong side, it will read incorrectly.

[Adam Hume]

i connected the guage by teeing in on the vacuum hose coming off of the fuel pressure regulator. I removed the BCS, installed the MBC, one side going to the waste gate actuator other side i tee'd into the vacuum line running from the BOV to the intake. Then caped the hole left on the airbox and the turbo outlet.

[mike griffin]

i always experienced problems when tee'ing into the bov line. I run mine like this:

Turbo outlet nipple

3" of hose

MBC

8" of hose

Wastegate actuator nipple

[Adam Hume]

so take the tee out of the bov to intake line, then connect that hose to the turbo oulet nipple?

[John Hartman]

I've actually had better results with it on the bov line, but thats with more mods. When it was closer to stock, it was better on the outlet elbow.

[mike griffin]

so take the tee out of the bov to intake line, then connect that hose to the turbo oulet nipple?

no

take your bov line, and plug it into the bov, leave it alone (till you get more mods) Then take your wastegate actuator hose, and plug it into the mbc, and keep the 3" of hose on the mbc already, and plug that into the turbo outlet nipple.