Quick boost gauge question

[TooFastTooG]

Hey guys got a question for you, I recentely replaced my old autometer boost gauge with a new one that I won ant a contest from work, there wasnt anything wrong with my old one but this was free, so i figured why not.

The gauge is an autometer ultralite series boost gauge, I also replaced the old crappy plastic tubbing with a nice silicone hose. Before I replcaced the guage I was idleing at a good -20hg and boosted nice to 15 psi, now with this new gauge It seems to be off (idle at -15hg and boost to 20psi). Before where I would start to build boost and the gauge would show that accurately, now when the car starts to build boost the gauge is at 5 psi, and the needle goes 5 psi higher then it used to, about 20psi.

So in short it seems that this gauge is about 5 off (in vac and boost). Does anyone know any causes for this? My car seems to have the same power so im thinking it may be a kink somwhere in the line?

 

[VelocitàPaola]

What does the gauge read when the car is turned off? If it isn't on zero, then your gauge is probably mis-calibrated. If you contact Autometer, they'll replace it no questions asked.

Like you already said, though, look for kinks in the vac lines too.

 

[TooFastTooG]

The gauge says "0" when turned off, I looked over it really good and couldnt find any kinks.

 

[VelocitàPaola]

Maybe your old gauge wasn't as accurate as you thought then. Idling at -15 inHg sounds more reasonable than -20.

 

[TooFastTooG]

Maybe your old gauge was off then. Idling at -15 inHg sounds more reasonable than -20.

Maybe your right, for some reason I thought I read somwhere that -20 was the best to be sitting at at idle. So that means I have been unknowingly boosting into the 20psi range? . That still make me wonder why though the gauge reads 5 psi when I can hear the car start to build boost. Weird.

 

[megadeth0]

From the sound of things, I think the New gauge is the one that is not calibrated right. If you were unaware that you were boosting 20PSI, chances are you did not have the car set up to run that high in the beginning. Which leads me to beleive you would have had problems if you were actually going to 20PSI. On the other note, you say it's already at 5PSI when you here the turbo spool, you shouldn't be instantly building 5PSI. The vacuum sound more probable at 15 though. So you may have two guages that are not very accurate. We all know these cheap guages are usually off, but not by 5PSI. Send the autometer back and they will recalibrate it for you. Good luck man.

 

[delta448]

I know that -15 inches hg is where my gauge sits at idle, so I'm fairly confident that reading is correct since you have a 8.5:1 2.0L same as I do. However I'm really curious about your 20psi reading... are you getting the gauge to hold at 20psi, or is that a spike? I read your vehicle profile, are you running the stock T-25? Is your MBC maxed out? Maybe you should try lowering the boost level with the MBC a bit and see if your readings are still around 17-19psi. Also, what vacuum line connection did you make for your gauge?

 

[TooFastTooG]

Hey guys, thought I would give an update to see if anyone else has ideas.

I got some hose and hooked the gauge up to there was only about a foot of tubing, so i was holding the gauge while standing at the engine bay, I did this to make sure I wasnt getting any kinks, and I wasnt and the gause still read the same.

And finally, I may have discovered my real source of the problem, I turned my mbc all the way down and I was still boosting to about 18 psi, this lead me to believe that my vac readings are probablt fine (about -15Hg), but my mbc is probably shot. Please let me know what you guys think, and also is it normal to be at about 15psi at half-throttle?

 

[megadeth0]

I think you are on the right track with the controller being bad. No, it is not normal to be at 15PSI at half throttle.

 

[TooFastTooG]

Ok so I ordered a nice MBC from DejonTool9they have never let me down before), I was running an eBay special MBC I know I know. Im not being cheap this time, we will see how things work when I get my new MBC, lets hope thats the problem.

 

[NMFDChris1G]

Hey guys i have a quick question, at idle my autometer boost gauge reads at 28Hz of vacuum an my turbo starts spoolin at like 5Hz of vacuum an my boost gauge only tops out at like 6-10lbs of boost so im not sure if my boost gauge is off or my boost is really down that much but i keep turnin it up an it dont go up any more any ideas??????????????

 

[ChvyKc]

Hey guys i have a quick question, at idle my autometer boost gauge reads at 28Hz of vacuum an my turbo starts spoolin at like 5Hz of vacuum an my boost gauge only tops out at like 6-10lbs of boost so im not sure if my boost gauge is off or my boost is really down that much but i keep turnin it up an it dont go up any more any ideas??????????????

Could be a really bad boost leak. I would run a boost leak test and see what happens.

 

[NMFDChris1G]

i thought the more vacuum the better?

 

[luvmygst]

Hey guys i have a quick question, at idle my autometer boost gauge reads at 28Hz of vacuum an my turbo starts spoolin at like 5Hz of vacuum an my boost gauge only tops out at like 6-10lbs of boost so im not sure if my boost gauge is off or my boost is really down that much but i keep turnin it up an it dont go up any more any ideas??????????????

Hz measures the frequency of sound waves. Vacume is measured in in/hg and boost in psi these are the terms mots people use there are acouple of others but thats another subject.

About the question, you have a miscalibrated boost gauge, normal vac. should be 15-25mm/hg and you should not build boost untill the needle passes zero. I would borrow a gauge from someone and check to see what it says. I think yours is wrong.

 

[NMFDChris1G]

oppss i meant to put Hg but yea i think the gauge is off cause even when i shut the car off its still at 11Hg of vacuum

 

[kazzam]

Maybe your old gauge wasn't as accurate as you thought then. Idling at -15 inHg sounds more reasonable than -20.

My gauge tells me i am adle at -19-20. I can confirm this with the greddy ebc too.


On another note. Try taking the gauge out and shaking it around and see if you can get the needle to get back to 0 (if it is not at 0 already).
I did some work with the car and noticed my gauge reads -5 with car off. the above helped to get it inline.

 

[ChvyKc]

My gauge tells me i am adle at -19-20. I can confirm this with the greddy ebc too.

I idle right around -20 as well. Just thought that I would throw that in.