I ordered and received an Autometer Phantom series Boost Gauge, Autometer part number 5776. I have a question or two about some connections. I need to connect the white wire from the light bulb to a source that is switched when the headlights are turned on (I know of the orange wire behind the radio but I don't feel like pulling out the radio if I don't have to). I also need to connect the red wire to a switched power source that maintains power during cranking. What/where are the two easiest/best places to tap in for the above two connections? Thanks guys.

- Josh

 

well In My 3rd gen I use the fog light switch for power and lighting or you can try head light switch

 

There are multiple places to choose from in the fuse box. I have my constant 12v source from the cig ligter and my gauge is lighted via my headlights IIRC.

 

Thanks guys. So the cigarette lighter maintains power during cranking? And where do I find the headlight wire/what color is it? Thanks.

 

Yep, I've linked into the cig lighter too. Works great!

 

Like I told James, my illumination was tapped into the tail light fuse.

 

Well, I spent some time last night to test where I will be tapping in.

Slimer Steve, your suggestion was perfect. I will use the 'Tail Lamp' fuse #5, 7.5 amp (R/G wire I believe). I hooked up a little test light and it only turned on with the headlights.

I30Mike and BlackCat, I tested the cig. lighter but, no, it does not maintain power during cranking. If you guys are using electric boost gauges, you might want to change your power source because the boost gauge recalibrates during cranking (at least with my Autometer gauge). If you have manual boost gauges, I don't think it matters.

I hooked my test light up to the cigarette lighter and sure, enough the light goes out during cranking. After a few trial and errors, I finally concluded that the fuses which maintain power during cranking are those marked with "IGN" (ignition) on the fuse panel (note the cig. lighter is marked "ACC"). If you look at your fuse panel, you'll see we have two 'Telephone' fuses (both 7.5 amps). Well, the one in the "IGN" section is the one I am going to use (I figured I might as well choose a fuse which isn't otherwise used). It is fuse #28 (green wire I beleive).

In conclusion, here are the names and functions of the fuses found in our driver side fuse panel:
"BAT" = always live, even with key out of the ignition
"ACC" = live when the key is in the 'Acc' or 'On' postion but not in the 'Start' position during cranking.
"Light" = live when the headlight switch is in the On position (regardless of key position).
"IGN" = live when the key is in the 'Acc', 'On' and 'Start' position.

 

Great detective work Ptatohed!
Thanks for the tips Steve!

 

good job guys.

 

Well, James and I finished installing the boost gauge last night - but it doesn't seem to be working properly. The needle sits at "-10" or 10 vacuum at idle and under light to medium throttle. As I give it medium to hard throttle, it gets up to zero. When I mash it, it slowly creeps to a max of five just before red-line. Then the transmission shifts and the boost drops and starts building again.

We feel good about all our connections. The vacuum was tapped in along side the Stillen provided 5 way splitter, the power was tapped into fuse #28 which does maintain power during cranking (as mentioned above), the ground was grounded to a bolt in the cabin where I have grounded other "toys". There are no detectable boost or vacuum leaks.

Any ideas what could be wrong? What kind of readings should I be seeing (at idle, at cruising, at WOT)?

Thanks guys.

 

well, which pulley do you have on?

I usually see -16in/hg when at idle. Engine braking is somewhere around -24in/hg.

I think the reason why my vacuum at idle is not as low (high?) is because my pvc valve is venting to the atmosphere.

I consistently see 7.6 lbs of boost on my 3.33 pulley.

 

Heck, that's less than mine at idle. I'm always at -15 at idle. I remember reading that -20 at idle is the norm.

I've got the Autometer Phantom series mechanical boost gauge btw.

 

Slime - Oh sorry, I have a 3.25" pulley.

B.C. - So what does your boost max out at?

 

I max out at 9 lbs and that's with the 3.125" pulley.

 

Could be a bad boost gauge. Wouldn't be the first time.

 

That would be nice. Of course it entered my mind but then I threw it out figuring it has to be me. But I guess I can try Jim's gauge, we bought ours at the same time, we just happened to install mine first.

So did I tap into the correct vacuum location? Is it o.k. that I grounded to a bolt/nut in the cabin or is it best to ground to the negative battery terminal? Arrrggghhhhh. :-/

 

In every boost gauge Ive seen, short of digital, the gauge will function regardless of how the wiring is hooked up, its a mechanical function. The wiring is just for the lights, and on some gauges, to record or set off an overboost warning. Regardless, the needle should still move and display properly.

 

If you have other things grounded to the bolt, it may be causing interference, but not likely.

The 5 way tee is alright to tap off of. Is the car running alright? No vacuum leaks? (you'll know what I mean if its happened to you before.)

Mtrai-I like that you're visiting this forum again. Why did you have such a long vacation?

 

P'head has the new Autometer electric boost gauge. It has a pressure sensor that send an electric signal to the gauge rather than the nylon hose tht the mechanical gauges have, so it is possible to wire it wrong.

I like to have my boost gauge connected to its own port. Usually that is not possible without drilling into the manifold and making one, however.

At any rate, disconnect the vacuum hose (at the manifold) that is feeding the 5-way connector and apply a vacuum to it with a Mityvac and see if all the hoses and devices connected to the 5-way are leaking or not. You may just have a split somewhere in one of the vacuum hoses.

 

SM-Slightly OT, but I was wondering how you could make the mityvac make something see pressure.

I am looking at tuning the sfmu. PM me about it if you do not want to clutter Josh's thread.

Thanks
Steve

 

My Mityvac has a port that you can connect the hose to that will provide pressure when you squeeze the handle. The gauge won't work in pressure mode, however, so you have to tee in another pressure gauge if you want to know how much pressure is being developed. I have the cheapo plastic version.

 

I just installed an SPI boost gauge today. I'm at -18 vac at idle, -21 vac during deceleration, 0 at medium throttle, and under WOT it slowly builds up to 7-8psi at redline (it's tough to look at the boost gauge and tach at the same time , but I know it's at least 7 psi). Using a 3.48" pulley here.

-Eric

 

Thanks for the info. Eric. Very helpful.

Well, I swapped in Jim's (The Wizard) gauge and MAP sensor - with almost the same results. I am still at zero at 'on', and still at 5 Max at top RPM but at idle/cruise I am reading 12 vacuum instead of 10 vacuum.

The car runs fine and performs fine. I did a thorough visual check for vacuum leaks - but didn't see any.

Stephen, I went to AutoZone to buy your MityVac but I did not see one. Will any vacuum gauge work? Explain one more time the principle please. Are you pressurizing the sytem to check for leaks or are you creating a vacuum? I thought at first you were pressurizing the system but they only had a vacuum pump at AutoZone and now that I am re-reading your post, I think that is what you meant.

I would be worried about something more serious like a worn/tired blower or a boost leak but since my vacuum is reading lower than it should (10-12 in-hg) at idle I am assuming it is either the boost gauge install and/or a vacuum leak. I hope anyway.

This is frustrating because this is the last thing James and I are waiting for before we install our custom water to air aftercooler (it took us months to do all the homework and purchase all the parts and now that we have all the parts, we can't get an accurate 'before' boost reading). We want an accurate boost reading before the cooler goes on so we can measure the exact boost loss throught the cooler. We are both installing one but we are doing my install first.

I guess my next step is to test the vacuum....

 

Josh,

The mityvac you can get at Sears. It creates vacuum. I am using mine to test pressure for the the SFMU settings.

As for your readings, it may not be a MAP malfunction, it could be the electronics in the gauge itself. Could you test his actual gauge?

I'm really excited to see how your air to water setup works too. It seems like I have pressure loss, but it also could be the condensing of the air through the intercooler.

Do you have your pcv connected to your piping? Mine isn't so its reads lower. I noticed tonite that I am getting -19 in vacuum. Could you post pics of how you set it up. It may take me a little to respond because of the fire, but you know that I'm there for help if you need it. Y'all have my number.
Steve

 

Thanks for the help offer Steve.

- Yes, the rental tool at AutoZone was, in fact, a MityVac. It didn't say it anywhere on the box but it does say it on the handle. See pictures in link below.

- As I mentioned in post #23, I swapped in Jim's MAP and gauge.

- I am not sure what you mean by connecting the PCV to the piping so I guess my answer is no. I have the PCV valve in the stock location.

- Fire?

- O.k., I took some pics last night. Please see the photobucket link below. I hope they are clear. Please let me know if you see anything wrong. Also, please take a look at my MityVac and confirm I got the right one. And, if you could, please provide me with detailed instructions on how to use it. You will see two MAP sensors for the boost gauge, one is James' from when I was comparing the two.

Thanks!

Boost gauge pics.

 

it looks a little beefier than the one that I got, but its still a nice unit.

My favorite part of the pics is the rubber band? that holds the manumatic and gauge to the steering column. hehe

Fire? My house caught on fire and we have to move out for 6 months for it to get rebuilt. Yuck.

Good luck Josh. I wish that I could be more help.
Steve

 

"My favorite part of the pics is the rubber band? that holds the manumatic and gauge to the steering column. hehe"

I thought you might like that. I am just winging it for now until I know my final set-up. I just can't bring myself to cut a hole in my instrument cluster so I have just had the manuamtic LCD just 'propped' for months now. I think my ultimate plan is to have two gauges as "Mickey Mouse ears" on my steering colum with the manumatic LCD in the middle of the two gauges. I'll have to build something pretty.

Could you provide a little input on how to use the vacuum gauge?

Sorry to hear about your house. Did you lose any irreplaceables? Does your home owner's insurance cover you? I hope you found a decent temporary home. That's a bummer - good luck to you. Try to get some upgrades out of the re-build. "Mr. Contractor, it may look like I only had a two car garage, but I had a three car, the fire destroyed the whole 3rd car garage".

 

Well, this may sound weird but I got a whole psi increase in boost by going from the stock 3" long filter to 4". Now I am up to 6 psi. Still too low though... :/

http://forums.maxima.org/showthread.php?t=440889

 

Not weird at all. What that means is that the stock filter was grossly undersized (or very dirty or both) and you had a substantial pressure drop through the filter.

 

im at -17 to -20 at idle and until i reach boost levels it stays at zero at cruising speed.

 

Oh man, this is frustrating. I used the MityVac this weekend. I got dead nuts the 20 hg.in vacuum at idle that BlackCat/others said was normal for our cars. But, like I said, my boost gauge reads 12. I even unplugged the vacuum line directly from the boost gauge's MAP sensor and hooked it up to the MityVac (where it read 20). So the boost gauge should read 20! And now I feel confident that I have no vacuum leaks. And I have already tested 2 different Autometer MAP sensors and 2 different gauges, both with similar results. So, this would point to the wiring but where can I go wrong with that??? Power and ground. <pound fist on desk a few times while making a frustration groan>.

 

I've been observing my vacuum at idle for quite a while now and my needle always hangs around 15 hg.in. Sometimes it will go to 17 hg.in (this is always when the engine is turned on and without pressing the gas peddle at startup). Now if I drive around a bit it will go to 20 hg.in but it will drop back down to 15 hg.in. I'm wondering if 20 hg.in is not a standard to go by anymore. Any thoughts?

 

15-20 is good vacuum give or take for driving conditions. you may see 20 if your dragging the gear to slow the car down or something but still seems reasonable. he says he sees the proper vacuum until he gets to the gauge so it has to be the gauge maybe a vacuum leak right where its connected or something wrong with the gauge itself.

 

According to the FSM - -17Hg to -22Hg is "spec"

My boost gauge shows -18Hg at idle and 13PSI at full boost. Almost 14 on an especially cold morning. -23Hg when engine braking on the freeway.

The gauge used to show low but I found out the fitting at the boost gauge was leaking. I used rubber hose over the nipple on the gauge instead of that fitting crimped into it. Problem solved.

 

Well, I guess I feel better now. We installed James' Autometer electric boost gauge (#5776) and he has the same exact readings as I. We both have a 3.25" pulley but he is 5M, I am 4A. We first used the MityVac and, sure enough, we got a reading of exactly 20 Hg.In (just like my car). After installing the gauge, he reads the same 10-12 Hg.In vacuum that I do. Just like my car did, his boost maxes out at 5PSI (mine maxed at 5PSI with my 3" filter and now at 6PSI with my 4" filter). This really blows. $190 bucks down the drain.

Autometer

 

Well,

I'm pretty pissed. I almost willing to go Greddy now and take the metric units.....At least I know they're accurate.

But some of you guys are using Autometer boost gauges, and are happy with them. Is it because they are mechanical boost guages? or? Are Josh and I the only ones using Full Sweep Electrical Autometer boost guages?

This sucks............

Autometer..........

 

I live near autometer. I was going to go out there a couple of months ago to check out their Nexus line, but after hearing this, I may just keep what I have.

 

what boost gauges are other ppl using? i still need one...would be nice to have a really cheap hidden one that can record my peak boost...

and one thats accurate also, sorry to hear about ure situation guys....

 

Ah-hah! The Wizard and I are golden! I just got off the phone with a tech at Autometer and it turns out we were given the MAP sensors for the 0-30PSI boost gauges. We have the 0-15 gauge. Sweet. He is sending them off tomorrow. I'm still a little upset that they would box the wrong parts - but as long as they make good on it, it's free and it is all good in the end - I'm happy. I can't wait for those correct numbers....

 

lol, yay, cool now i can go buy one...