Boost gauge readings.....

[Tensor187x]

What are some things that could be causing a boost guage to read incorrectly? :confused:

I've got a boost guage hooked up to my s14 SR, which has only got a 3" DP, FMIC, and a HKS bov. I've never messed with boost on my car at all, nor do i even have the stock boost selenoid. My boost gauge is reading 17psi and i don't understand how that is possible?

If anyone could chime in, please be of help! :angel:

[japslapsilvia]

where are u getting the signal for boost?
what type of gauge is it?

[ANVIL]

could depend on the gauge (if its cheap) and also how you plummed it to read

[burnsauto]

i usually tape in between the fpr and the throttle body. i always get an accurate reading from that line.

are you sure you don't have the wastegate signal line unhooked and you're actually pushing 17psi? :keke:

[MR_X]

Try to borrow someone elses boost gauge to verify the reading, either your gauge is broke, or you're really boosting 17 psig.

[looking4-240]

you can borrow mine malarky...........................i think it very well could be you're boosting 17psi

[GSXRJJordan]

First of all - make sure you understand the difference between boost and vacuum - vacuum is measured in "in Hg" or "inches mercury". Much different than psi (which is a measure of pressure) - the engine 'sucks' air into it whenever the turbo's not 'pushing' air in... this is a source of confusion to those new to boost gauges.

At idle, your engine should pull somewhere around 20 in Hg - this could be what you're reading as "17 psi" except it's on the wrong side of 0.

As you step into the throttle in 1st or 2nd, you should see the boost gauge rise very quickly to 0psi, meaning no boost, and then if you give it some more gas it'll go into "boost" and you'll see somewhere around 7psi on a stock motor.

[Tensor187x]

It's an Autometer boost gauge. I know it's probably the cheapest one you can buy, but my brother had it hooked up to his 1JZ and it was working correctly. Is it possible that i have it hooked up to the "wrong" vacuum line? Is there a special spot i should have it T off to?

[reccakun08]

usually T off on the vacuum port where the FPR is connected to on the TB

[Tensor187x]

Alright, i'll go ahead and try that!

And what did the other guy mean by "are you sure you don't have your wastegate singnal line unhooked?"

Thanks.

EDIT: This is where i have it connected.
http://i16.photobucket.com/albums/b42/Borund/1119081329-00.jpg

[SidewayZ-s14]

That's where i have mine T off to.

[GSXRJJordan]

That's a fine location. You didn't answer my questions as to whether or not you know what you're looking at... no offense.

[djcobra]

If you don't have a charcoal canister installed then you can use the spare vaccum line under the throttle body. There are 2 vaccum ports under the 'Throttle Body' one goes to the BOV, and 2nd is spare, most guys cap it or you can run it straight to your wastegate/boost controller or to your boost gauge. I try not to 'T' off vaccum lines as it causes boost problems and other crap down the road. If you ever do get a high quality boost controller, such as Blitz or HKS, then you usually 'T' off from the FPR line. I have a feeling you have a faulty gauge or your not reading it right as GSXRJJordan stated... I have nothing against Autometer products, but i'm usually picky about my parts and I stick with mostly JDM shit, ie, GReddy, HKS, Blitz, Defi, etc... Anyways, good luck.

Steve.

[reccakun08]

a little off topic but do most of you tee your boost controller into? (no nipple on hot pipe or turbo)

[GSXRJJordan]

Whatever your wastegate is currently connected to, because the wastegate connects through the boost controller. If you need a second vacuum source for the control box/etc, I just tee the same vacuum line as the boost gauge is on.

[reccakun08]

Currently using a different hotpipe setup with no nipple. Before my wastegate went to boost controller and to hotpipe nipple. Now that i do not have a hotpipe nipple where should it route back to?

[GSXRJJordan]

Throttle body has some nipples you can use. Most people only use 2, and have the 3rd capped - one for FPR, one for wastegate - take a peek at the corners of the throttle body for your nipples.

[Tensor187x]

That's a fine location. You didn't answer my questions as to whether or not you know what you're looking at... no offense.

My idle reads about 15hg at idle, but when im in 2nd gear giving it some boost, the needle EASILY goes to 0, and then all the way to 17psi. Tried a different boost gauge and still reading 17psi.

[Sileighty_85]

So your just running a vacuum line straight to the W/G? W/G actuator might be shot (broken Diaphram)

[GSXRJJordan]

My idle reads about 15hg at idle, but when im in 2nd gear giving it some boost, the needle EASILY goes to 0, and then all the way to 17psi. Tried a different boost gauge and still reading 17psi.

Well, that's what we needed to know. You've definitely got something wrong with your wastegate, or you're tee-ing your BOV to the wastegate line and it's leaking air?

Make sure your wastegate and BOV have their own hoses to the throttle body, for starters. If they already do, look into getting a HKS wastegate actuator (great investment, and only $100 new, ~$70 used).

[Tensor187x]

Well, that's what we needed to know. You've definitely got something wrong with your wastegate, or you're tee-ing your BOV to the wastegate line and it's leaking air?

Make sure your wastegate and BOV have their own hoses to the throttle body, for starters. If they already do, look into getting a HKS wastegate actuator (great investment, and only $100 new, ~$70 used).

It could be that they dont have their own vacuum lines to the TB. I'll have to check that. If they do infact have their own, i guess it's time for a new wastegate. Thank you guys for all your help! :]

[sc300fivespd]

TITS, okay now that i have ur attentions. a wastegate unless u have a boost controller needs a straight line to a point in the system that holds boost, for best acuracy and boost control. if for some reason there is something else on the same like as the wastegate, get rid of it. unlikly, but have you taken off the wategate or anything recently? if the actuator on the wastegate gets bent or something it will boost higher than normal....

[g6civcx]

Throttle body has some nipples you can use. Most people only use 2, and have the 3rd capped - one for FPR, one for wastegate

Wastegate signal comes from TB?

[GSXRJJordan]

Wastegate signal comes from TB?

With no boost controller, it can come from a lot of places - could come from a nipple on the hotpipe, a nipple on the compressor housing itself/etc. Stock setup has the wastegate and the "popoff" valve both getting their own lines to the throttle body, in addition to the charcoal canister and FPR.

Talked to the OP via PM's, I think he had some routing problems, and I'm sure he'll post again when he has them taken care of.

[Tensor187x]

With no boost controller, it can come from a lot of places - could come from a nipple on the hotpipe, a nipple on the compressor housing itself/etc. Stock setup has the wastegate and the "popoff" valve both getting their own lines to the throttle body, in addition to the charcoal canister and FPR.

Talked to the OP via PM's, I think he had some routing problems, and I'm sure he'll post again when he has them taken care of.

Jordan FTW. It worked! It doesn't read 17 anymore! :w00t:
lol, i feel like a loser. It reads 7psi now, exactly what it should be reading! :coolugh:

[GSXRJJordan]

Jordan FTW. It worked! It doesn't read 17 anymore! :w00t:
lol, i feel like a loser. It reads 7psi now, exactly what it should be reading! :coolugh:

Glad we got it figured out. The car might feel a little less torque-y, but now you can put your foot in it and not worry about anything.

[Tensor187x]

Glad we got it figured out. The car might feel a little less torque-y, but now you can put your foot in it and not worry about anything.

Yeah, i was going to mention that! :cry:
I didn't know if i was just trippen cuz i thought i fixed something or it actually is less torquey. I loved the torq! Noes! :trogdor:

[Mr.s13r]

Got a question about boost reading also, Op, sorry not mean to thread jack. I have a s13 blacktop and run all the hose already. Fpr goes to boost control (not turn on yet) also t off for boost gauge. The top right hose from throttle body to BOV and bottom cap off. Wastegate is t off with greddy profec 2 spec b sender. I try to hit boost today to see where i am boosting at but get like 10lbs, this is again with the boost controller not turn on ( didn't hook up the electrical wires yet). idel at 20 hg vacuum. I got this reading in second and third gears since i heard in first, it can't build enough boost yet. Lmk what's going on. thanks

[Tensor187x]

LOL just drove my car again and it's pretty slow. Feels like im driving a KA. Now im starting to think my routing of hoses was acting sort of like a bleader valve allowing me to boost more. My BoV sounds quieter, My car has slower reaction time, and it's slow lol! I think im just going to risk it and put back on the T! :P lol i really can't stand it being like this! It honestly felt like a volswagen bug could smoke me!

Thanks for all your help. Now i understand why it was reading incorrectly.

[g6civcx]

Stock setup has the wastegate and the "popoff" valve both getting their own lines to the throttle body, in addition to the charcoal canister and FPR.


What engine are you talking about?

[GSXRJJordan]

Got a question about boost reading also, Op, sorry not mean to thread jack. I have a s13 blacktop and run all the hose already. Fpr goes to boost control (not turn on yet) also t off for boost gauge. The top right hose from throttle body to BOV and bottom cap off. Wastegate is t off with greddy profec 2 spec b sender. I try to hit boost today to see where i am boosting at but get like 10lbs, this is again with the boost controller not turn on ( didn't hook up the electrical wires yet). idel at 20 hg vacuum. I got this reading in second and third gears since i heard in first, it can't build enough boost yet. Lmk what's going on. thanks

I don't see what the problem is... "like 10psi" could be the stock 7psi from the wastegate spring spiking a little - your idle is good, so no leaks... sounds fine.

LOL just drove my car again and it's pretty slow. Feels like im driving a KA. Now im starting to think my routing of hoses was acting sort of like a bleader valve allowing me to boost more. My BoV sounds quieter, My car has slower reaction time, and it's slow lol! I think im just going to risk it and put back on the T! :P lol i really can't stand it being like this! It honestly felt like a volswagen bug could smoke me!

Thanks for all your help. Now i understand why it was reading incorrectly.

It wasn't "reading" incorrectly, you were overboosting! 17psi is WAY too much boost for that t28 on stock MAF/injectors. You WILL damage your engine if you put it back and keep it that way. Don't be dumb.

What engine are you talking about?

SR20.

[Mr.s13r]

thank for the reply jordan

[Tensor187x]

I don't see what the problem is... "like 10psi" could be the stock 7psi from the wastegate spring spiking a little - your idle is good, so no leaks... sounds fine.



It wasn't "reading" incorrectly, you were overboosting! 17psi is WAY too much boost for that t28 on stock MAF/injectors. You WILL damage your engine if you put it back and keep it that way. Don't be dumb.



SR20.

Yeah, thought so. I know 17psi is WAY too much for that t28 but believe me, i wont be driving it like that. I know better than to push a stock t28 to 17psi. I've only done it like once and it read 17psi thats why i was pretty scared.

[g6civcx]

SR20.

I was always under the impression that the factory plumbs the wastegate to the IC piping. It was like this on my redtop.

Can you clarify?