korea_senpai

iTrader: (25)

I took sometime to install my BNR stage 3s and upgrade my radiator to a 3 row type. Put everything back together and I don't have any vacuum at idle, sometimes it will read 2 or 4 but most of the time so far while troubleshooting its been at 0. I took it for a drive and my AEM mechanical boost gauge, which I've tested, says it is hitting 14psi around 3000 rpm. I've done all the vacuum leak test and have come up with nothing, my MAP sensor is connected securely. I'm at a loss.

Mod list: Greddy M-spec FMIC
Greddy Pulleys
Greddy Elbow
HKS Hi-Power Catback
HKS RS Intake
HKS downpipe
Midpipe
FAMC reflashed ECU to support mods
Double Throttle Elim
ACV Elim
Air pump Elim
EGR ELim

Maybe I'm just over looking something small (duh) any suggestions? Thanks in advance. By the way it is a JDM model, RHD and stuff, if that changes anything?

Bin

djseven

iTrader: (56)

Have you ran a boost gauge directly off of one of the two nipples on the RHD side of the UIM?

zeroG

iTrader: (28)

What are you using to read the vacuum numbers? Does the car idle fine or is it stumbling?

If it idles and runs fine at lower rpms it is likely something wrong with the gauge or the way you installed it

If you had a vacuum leak you should not be able to build pressure to 14 psi either

Brodie121

iTrader: (8)

Do you have the boost gauge hooked somewhere that has a check valve in between it and the vacuum source?

korea_senpai

iTrader: (25)

djseven - yes my boost gauge is using the right nipple on the UIM for readings.

zeroG - I'm using the AEM mechanical boost gauge and the car idles perfectly, I thought I had installed the gauge wrong but went and checked it and everything was fine, while I was building pressure during yesterdays drive it didn't feel like there was barely any power, and my bov sounded weird, like it was surging or almost as if there wasn't one on.

Brodie121 - Hey man, hope you got all your stuff from me, no I'm using the UIM nipple.

Here is a question then, I'm not using the JDM UIM that came with the car, I'm using a polished USDM one I bought off a forum member with the double throttle removed, so would the difference in origin of UIM change anything?

djseven

iTrader: (56)

Take a short piece of vacuum line(less than 2 feet long) and hook it to the UIM and Gauge. That will eliminate any disturbance. If you have another gauge laying around try it.

The double throttle removal should have no effect.

DaleClark

iTrader: (55)

The engine would flat out not run or run terribly if it truly had no vacuum.

My guess is the boost gauge is petering out (not that big on AEM gauges) or you have a kink in the line or something limiting the signal back to the gauge.

Dale

korea_senpai

iTrader: (25)

So I went and got a cheap gauge at Advanced Auto and came back tested it and I had vacuum, I plugged in the AEM gauge and I had vacuum, what the heck....any ideas what might have happened?

MR_Rick

iTrader: (7)

you probably pinched the line some where behind the gauge.

korea_senpai

iTrader: (25)

Thats the only thing I can think of....I'm coming down to Virginia Beach next weekend to see my girlfriend, hit me up if you're free, 757-287-1673

Bin

korea_senpai

iTrader: (25)

The gauge isn't zeroing because whenI turn the key it turns on the gauge but actually crank the engine to start the car all my electronics snap off and snap on which causes the gauge to lose zero. What might cause the electrics to do this?

RotaryEvolution

iTrader: (30)

the ignition switch cuts power to most everything during cranking, that is normal.

if it is a mechanical gauge it is automatically zeroed, unless you are backwards and it is an electrical gauge and not mechanical which can cause many more possibilities as the cause of the issue.

korea_senpai

iTrader: (25)

No its a mechanical gauge, I not sure how to explain it.....the vacuum hose comes out of the UIM leads to a sensor which is electrically connected to the gauge in the car. When the car cranks and cuts power it resets the gauge and while its trying to zero there is already vacuum and messes the reading up.

korea_senpai

iTrader: (25)

Ok, what doesn't shut off while cranking your engine, or which wire is the ignition wire. I don't want to sound lazy but I've been on this project for almost 3 weeks straight and its starting to rack on my nerves.

Turbo8

iTrader: (17)

I have the same gauge you do, it is an electronic gauge.

AEM gauges automatically calibrate to zero when they boot up. I had this same problem with my gauge because when you crank the car, most auxiliary electronics are turned off for maximum cranking power. If you have your gauge power wired into a circuit that gets turned off during cranking, the gauge looses power and thinks it's shutting down. So then once the car starts, the gauge boots back up and recalibrates the sensor to what it thinks is atmosphere, but now it is really engine vacuum...get my drift?

I did the same thing when I installed mine, then I re-read the instructions and it says you need constant 12v even during cranking, so I re-wired the power source to the fuel pump fuse in the kick panel (I have my fuel pump re-wired with a relay so it's not taking any power from the pump) which stays on during cranking.

Hope this helps,

korea_senpai

iTrader: (25)

SO its like a hybrid gauge, but yeah I kind of figured I'd find out what didn't turn off when starting the engine but didn't know for sure what did and what didn't.

RotaryEvolution

iTrader: (30)

there's nothing hybrid about it, even the electronic MAP sensor on your car that the ECU reads the vacuum signal off of has a physical connection to the engine via a vacuum line.

it is electronic, the sensor itself may be going out or the gauge needing to be recalibrated with some sort of reset.

edit: or do what turbo8 said. it's important that the 12v feeds for gauges and electronic equipment is applied to the right circuits or it can cause issues like this or automatic resets each time you crank the car/shut it off.

korea_senpai

iTrader: (25)

Fixed it, just found a live source of power and added a toggle switch, switch on before I start the engine and switch off when I get out of the car.