Boost gauge only reading vacuum

[jakelandry]

I know this has been covered a thousand times but after reading 20+ threads on the matter noone seems to have the same situation as me. I bought a car recently and it came with a glow shift 30-0-30 gauge in it and when the car is off it reads 0. Once i crank the car it reads inbetween 18-22 vacuum. When i give the car a little gas it jumps up to around 10 vacuum. When i hit well into boost the gauge just reads about 0. I know it is not the gauge because i actually had a gauge that i know for a fact works sitting in my room that i swapped out and it does the exact same thing. I can take the gauges and blow on them with my mouth and they will read a few psi so it cant be the gauges. The gauge line is tapped into the intake/fpr line. One thing, i dont know wether it will make a difference or not but i just pulled the center console up and found a avcr unit thats working, could the way it is installed have any impact? And yes it did make my dad when i found the avcr because to my knowledge the car was stock .

 

[Jezza]

Where is the gauge hooked up? If it's on the wrong side of the turbo, it won't show boost. Also, make sure that the line to the boost gauge doesn't have a check valve in it. (I've actually seen this done before. )

 

[black_gst]

Where is the gauge hooked up? If it's on the wrong side of the turbo, it won't show boost.

on the right track, where is you boost gauge tee'ed off from, show us a pic

edit:

well the avcr could def be causing a problem since its a boost controller, but im not familar with the unit. see if you can bypass it.

 

[jakelandry]

on the right track, where is you boost gauge tee'ed off from, show us a pic

edit:

well the avcr could def be causing a problem since its a boost controller, but im not familar with the unit. see if you can bypass it.

I teed off of the intake to fpr line, not the line that runs beside this line. It is a direct path from the device with the twistable knob and the intake manifold. I tried running directly to the vacuum with the gauge and i get the same reading as i do from the line run to the inside of the car. I dont know a thing about the avcr, i cant even find the solenoid valve. Is there any other line i can tee off of just to see if ill geta boost reading? I have a cyclone intake manifold also, im assuming that does not matter though.

 

[Jezza]

You should be able to get a good boost reading from anywhere between the turbo and intake. Just make sure that if you are splicing into a line that it doesn't have a check valve between the splice and the source.

 

[courtneyh28]

I would try to switch out with another boost gauge. Just to make sure thats not the problem???
From ## explination it sounds like u have it Tee'd into a good spot.

 

[rlacasse1]

I vote it is because it's a glowshift gauge.

 

[Jezza]

I would try to switch out with another boost gauge. Just to make sure thats not the problem???
From ## explination it sounds like u have it Tee'd into a good spot.

He already checked that:

I know it is not the gauge because i actually had a gauge that i know for a fact works sitting in my room that i swapped out and it does the exact same thing.

 

[rlacasse1]

Oh, well screw my post then.

 

[courtneyh28]

Damn Me too. I gotta learn howto read

 

[2gGSXEclipse]

Arent some of the vacuum ports off the intake manifold/throttle body only used for vacuum, they might have a check valve in them that close once it hits boost. Id try hooking it up to another vacuum port.

 

[Jezza]

From everything that I've seen, the best place to get a good, accurate boost reference is in the UICP, after the BOV, before the throttle body(if you have a hard pipe). That is after any pressure drop that an intercooler may have.

Otherwise, tee into the pressure line into the wastegate actuator.

 

[2gGSXEclipse]

From everything that I've seen, the best place to get a good, accurate boost reference is in the UICP, after the BOV, before the throttle body(if you have a hard pipe). That is after any pressure drop that an intercooler may have.

Otherwise, tee into the pressure line into the wastegate actuator.

Do not do this. The wastegate should have a line of its own and not share a line with anything. The wastegate line should come off the J-pipe, or any pipe right after the turbo directly to the wastegate.

 

[rlacasse1]

Well if he has it tapped into his FPR line then he should be fine.

 

[Jezza]

Do not do this. The wastegate should have a line of its own and not share a line with anything. The wastegate line should come off the J-pipe, or any pipe right after the turbo directly to the wastegate.

That's what I thought too, but a Toyota tech article for the MR2 I was just reading said different.

 

[jakelandry]

Well we can all stop debating. I have absolutely no clue how but it began working. I tested it with 2 boost gauges, and my avcr and none of them would read over 0, then for some unknown reason they all began to work correctly. I have absolutely no clue how or why, which is really dissappointing because im sure someone else will have this problem eventually and i can offer no answer.

 

[Couger85]

Isn't your car a N/T??? If you dont have a turbo then all you are going to get is vacuum.

 

[Zack Huffman]

From everything that I've seen, the best place to get a good, accurate boost reference is in the UICP, after the BOV, before the throttle body(if you have a hard pipe). That is after any pressure drop that an intercooler may have.

Otherwise, tee into the pressure line into the wastegate actuator.

To read the pressure entering the engine you'll want to be tapped into the intake manifold. The pressure in front of the throttle body can be different than what the maniold sees under partial throttle.

Also, for accurate readings, do not tap the wastegate line -especially if you have a boost controller.

 

[jakelandry]

Isn't your car a N/T??? If you dont have a turbo then all you are going to get is vacuum.

I have a nt and a gsx i just have not updated my profile because the gsx is about to go through drastic changes and ill just be modifying my profile constantly.

 

[Couger85]

I figured that was the case after I posted that.

 

[caseyty13]

I know this is an old thread, but I was given a glowshift boost from a friend. Before I hooked up the wiring, I wanted to test the gauge to make sure it would even read once it was hooked up to a vacuum line. I am having the same problem. When I start the car it reads around 18-20 vacuum, but when I rev up the engine it just goes to 0. And it won't go higher. My car is mostly stock. I have the vacuum tee'd off of the vacuum line to the fpr. I checked for vacuum leaks and I'm not finding any. What could be the issue. The only upgrades I have on the engine is an Injen intake and replaced the stock intercooler piping with hard piping. So I'm lost. And the vacuum line isn't being pinched at all.