What would cause a boost gauge to read lower boost then the actual boost?
Would a pinch in the line cause it?
I have already checked to see if I have any leaks and I don't. the gauge reads about 600 in vacuum, so I am alittle lost now.

 

well its either the gauge isnt working properly or you might have a leak. can you swap out the gauge if possible. recheck all your connections especially the one attached to the gauge and see if it's loose or leaking. i was loosing vacuum and it took me a month to find it, it turned out to be the hose that connected to the fpr had a little split in it.

 

I second checking for a leak at the gauge. When I first installed mine I had to do the connection over again at the gauge cause that plastic line crimped a bit right at the gauge and gave a false reading. I had to cut about an inch down on the plastic line and reinstall that plastic ball on the line and retighten it back on. **Make sure you tighten down with a wrench, not hand**

 

yeh that little white hose bites, not too flexible.

 

I will check that. But I have the Greddy guage and it just takes a regular vacuum hose to it with no nut or clamp or anything. I have a tie wrap on it just in case. Also I repalced all the lines with silicone lines too.

I will post after I look.

 

i dont know if it makes a difference on the size of tubing you use, but i know the white tubing is vey thin compared to a regular hose line.

 

Ptatohed and the wizard had the wrong sensor attached to their gauge (which happened to be an autometer electrical gauge)

I would call up the manufacturer and see if you have the wrong boost sensor.

 

thier clear get it wright.

no your right they are ****ty I cut mine close to the gauge and shoved a vacumm line on to it to run it throught the fire wall.

 

Latin, what gauge do you have? Mechanical or electrical? Recent install or did this problem just start from one day to the next? Like Slimer mentioned, The Wizard and I bought our electrical Phantom Autometer gauges at the same time and both came with the MAP sensor for the 0-30PSI meter (we have the 0-15PSI gauge). We read about 2/3 what we should in both boost and vacuum (12 vac. instead of 18 and 6-7 boost instead of 10). Not sure if that info. will help you but I thought I would pass it along. Good luck.

 

Greddy mech. and it happened after I installed the FMIC, water/alcinjection, 510cc injectors.
I hope it is the gauge or the line. I don't think the FMIC would cut boost in half, if it is it sure is running a really hard.

 

600 in vacuum doesn't sound right. Rent a mightyvac from AutoZone to test your vacuum. If the MightVac reads the normal 18-20, then it's your gauge. If the MightyVac also reads 600, then start searching for the vacuum leak.

What peak boost are your reading and what peak boost were you expecting? Be prepared for a 2PSI drop across your FMIC.

 

I am reading 5-6 psi and with the 2.87 pulley I though it that it should be around 12-13, I may be wrong, but I don't remember.

 

You should be seeing around 10-11 PSI with a 2.87" and an intercooler. 12-13 would be without a 2PSI loss across the cooler. I am seeing 10-11 with my water-to-air and 2.87". Like I said, expect a 2PSI loss across the cooler. Did you rent the mightyvac yet?

 

i have a question which might sound dumb, when u r idleing do u have vaccum with a s/c max. bc my guage shows 0 when im idleing and goes up to the regular PSI when im boosting. i have a reuglar autometer boost gauge.
thanks!!!

 

yeh your suppose to read vacuum, im at-18 at idle.maybe you have it hooked up to a wrong source i know i had that problem till i switched it.

 

ok, where should i have my boost gauge line hooked up to?

 

you probably have it on the non vacuum line, i would try vacuum from the manifold. i have mine running from the fpr vacuum.

 

ok i hooked it up off my 5-way T adapter and when i do that my blow off valve sounds different, and i get vaccum but when i hit the gas it only comes up to 0. then when i get on it the boost gauge only goes up just a little bit. when i had it hooked up to the other line at idle it was at 0 and when i would get on it the gauge would go up to 7-8psi. now it doesnt. any ideas??????

 

n/m fixed it had a leak coming from the gauge tightened it up and its all good now, thanks for the help C MAX

 

I just put the clear hard line into a soft rubber hose then that to a bigger hose that goes completely over the bolt that things screw into on the bottom of the gauge.

Airtight and reads perfectly now. 18-19Hg Vacuum, 14.5PSI of boost.

 

14.5PSI????????

 

Yeah - I really gotta take a pic sometime....but it's too difficult while driving.

Maybe I'll have someone sit in the back seat with a camcorder.

 

My gauge has peak memory.