Die For MX

I have my greddy electronic boost gauge installed finally. With the mods I have my car spools up to 12psi, which when converted should be about .844kg/cm^2. It had the proper boost when I bought the car. The car still pulls just as hard as it did when I bought it. But after installing the gauge and taking the reading it seems inaccurate.

I know I've heard plenty of times about how electronic gauges are innaccurate, but I'm trying to find out why. So its reading between .5-.6 kg/cm^2 which after converting it is only 7.11-8.53psi.

The transition appears correctly on the gauge. It feels as if its still building boost but on the gauge it doesn't appear to build boost after the .5-.6 range. Also sometimes the vacuum reading is 100mmHg off from what my s-afc reads.

Is there anything I can do to correctly calibrate the gauge? Is the length of the vacuum line from the FPR too long causing a higher frictional loss? Could voltage to the gauge be a problem?
Have you guys with this type of gauge ran into the same problem?

Its still valuable in the fact that I can see if it will spike but I would just like to read an accurate gauge.

Thanks
Kevin

Die For MX

^

hapa

Where do you have the gauge monitoring boost? Where is the boost sensor connected for the SAFC? You can always borrow a vacuum pump from autozone or a mechanic, plug it into your sensor and test it out.

eric

Die For MX

I have a vacuum line T-d into the FPR vacuum line. Then to the boost sensor like the greddy manual says. The s-afc takes the reading from the ecu.

hapa

Have you tried plugging the sensor into nipple on the upper intake manifold? That's where I have mine connected to and it's pretty accurate. Try the other just for kicks and see what data you come up with.

eric

Die For MX

haven't tried that yet, just tried what the manual said. I'll give it a try this week though. Thanks for the idea. BTW...is your gauge mechanical or electronic?

hapa

I have the 60mm electronic peak hold one. I first installed it 3 years ago when I bought the car, and tested it and found it very accurate. I used a snap-on vacuum tester so I know it was accurate back then. I suppose I should re-test it, just to double check.

eric

Die For MX

ok so you have a vacuum line coming directly from one of the UIM nipples right to the pressure sensor, then from there to the data link? Hopefully this will solve all my problems ...
I wonder why on page 7 of the manual it depicts the FPR vacuum line forming a junction with the greddy vacuum line w/ the 3-way joint.
Anyway....hapa, i'll give that a try and get back to you with the results.
Thanks,
Kevin

hapa

Kevin, I didn't bother to read the instructions with my gauge, they were in Japanese, the only part I could read was the wiring diagram for the control box. So I wired it up, pluged the sensor into the nipple on the intake manifold and fired it up. Let me know what your results are, I have to re-test my sensor to see if it's lost it's calibration.

eric