Boost gauge hits max set psi, then falls?

[TheTSiGuy]

Just started happening tonight. I'll floor it, and it hits15 psi, no problems. But as soon as it hits 15 psi, instead of staying constant, it falls. Is this a boost leak or something? are there any other typical ways to tell if i have a boost leak?

Also, another question.

My factory boost gauge doesnt work, which is sorta ok since i have an aftermarket gauge on my pillar. Is there any way i can fix the factory gauge though? every other gauge works, except fort that one.

Thanks!

 

[Forced4]

Not sure about the factory guage, but I'll look into it. As for the boost falling off. Yes that would likely be a boost leak. First things first, check ALL the hose clamps from turbo to throttle body. Then check ALL vac lines. IF all is well there, you may have lost a gasket(BOV, T-BODY, INTAKE) something like that. Don't forget to check the lines for the boost guage as well. A leak is a leak.

Forced 4

 

[TheTSiGuy]

aha, so i am most likely experiencing a leak then. good to know. I thought my turbo was going to blow up or something. Ah, the ignorance of my thinking :laugh:

I'll have to go throughout and check.


Also, Would anyone happen to know which warning light im having go off? Its on the left side of the cluster, its the farthest right. It looks like some type of oval with lines in it. I have the haynes manual beside me, and its not much help.

Thanks!

Jim

 

[TheTSiGuy]

Actually, i have another dumb question.

I remember quite some time ago, i was driving with the owned of Ultimate Z in his 300zxTT...we noticed that his boost gauge wasnt moving in once instance....so we pulled over, and he blew a hose off. We re-connected it, and voila! boost guage works again. IS there some kind of hose that would do this with a DSM I went under my hood a few minutes ago and looked at all the clamps and tightened every screw i could find. I also pushed all hoses back onto where they should be as best as i could. I hope it will help some.

Any other input?

Thanks!

 

[flytalon93]

Well the only way to see if what you just did helped is to take her for a spin. Then diagnose whether any of that helped. I would also suggest a boost leak tester to help track down all leaks.
Good Luck
Steve

 

[turboholic]

Originally posted by TheTSiGuy
My factory boost gauge doesnt work, which is sorta ok since i have an aftermarket gauge on my pillar. Is there any way i can fix the factory gauge though?

-Unlike your aftermarket boost gauge, the OEM boost gauge doesn't actually measure vac/pressure, it's just an estimation from the ECU according to the input it has receive from sensors, so a loose hose won't effect the OEM gauge. If you are running high boost, should consider upgrading to better worm drive clamps or T-bolt clamps.

 

[mrmadmax]

Originally posted by TheTSiGuy
Actually, i have another dumb question.

I remember quite some time ago, i was driving with the owned of Ultimate Z in his 300zxTT...we noticed that his boost gauge wasnt moving in once instance....so we pulled over, and he blew a hose off. We re-connected it, and voila! boost guage works again. IS there some kind of hose that would do this with a DSM I went under my hood a few minutes ago and looked at all the clamps and tightened every screw i could find. I also pushed all hoses back onto where they should be as best as i could. I hope it will help some.

Any other input?

Thanks!

The factory boost gauge gets it's information from calculations made by the ecu. There is no real pressure measurement (on the 1G's at least) other than the baro sensor in the MAF.

To answer your question, fixing all the vacuum lines won't help much....

 

[mrmadmax]

Originally posted by turboholic
-Unlike your aftermarket boost gauge, the OEM boost gauge doesn't actually measure vac/pressure, it's just an estimation from the ECU according to the input it has receive from sensors, so a loose hose won't effect the OEM gauge. If you are running high boost, should consider upgrading to better worm drive clamps or T-bolt clamps.

Beat to the punch!!

 

[TheTSiGuy]

Ah, so is there no hope for fixing my factory boost gauge?

Also, what do you guys consider high boost?

 

[TheTSiGuy]

Also, anyone have a diagram for where all my vaccum hoses are? also, any diagrams for where the boost could leak would be nice. Gotta check em all.

 

[turboholic]

-Taboospeedshop.com

 

[TheTSiGuy]

ok, so no hope for my factory gauge.


And anyone happen to know which warning light im talking about in my first post?

The one on the left side of the cluster, furthst right.

 

[turboholic]

-You can try pulling the entire gauge cluster off and try reseating the connectors a few time, that whole cluster is one big circuite board.

 

[turboholic]

-Look like a Roman building? it's the low coolant light, check the coolant overflow reservor.

 

[TheTSiGuy]

Looks like the roman building, correct!

Looks like i need coolant, eh?

good to know. I thought it was something far worse.


Thanks!