Boost Gauge Installation FAQ

The boost gauge is perhaps the most common, and overlooked mod in the DSM community. I have yet to see a full up FAQ on it's installation; at least on the 2g cars. I can't count how many times some poor newbie (yes my hand is raised :) asked the questions: Where do I tap my gauge? Where do I get power for the light? Well look no further. I will help you new guys as best I can since everyone else (my self included sometimes) takes for granted the most often performed mod as if the knowledge of how to do it were implanted in your brain at the time of sale (ya, SATAN teaching you a mod . . . DOH). Anyway here we go:

Parts:

Tools:

Installation Steps:

  1. Decide where you are going to mount the gauge and how (I'm going to assume and A-pillar cup:).
  2. Trim the A-pillar mount so that it fits the way you want it to.
  3. If you're going to drill holes to attach the cup drill them now.
  4. Ensure proper fitting of the cup and A-pillar and alignment of the holes you've drilled.
  5. Cut a hole on the steering boot.
  6. Run the hose through the firewall.
  7. Tap the Fuel Pressure Solenoid.
  8. Attach the hose to the gauge. (You might want to test the setup by starting the car at this point).
  9. Make the connections for the light under the dash.
  10. Run the wire to the cup and attach it to the gauge light (Again I suggest testing it now).
  11. Attach the cup (make sure the hose and wire are already going through the cup :).
  12. Slide the gauge in place.
  13. Hide the hose and wire.

Explanations:

What Kind of Boost Gauge should I get?

Preferably one which reads from -30inHg to 20psi (or 30psi). If you get one that only goes to 15psi you might as well save your money for the next gauge you're gonna buy, cause 15psi just won't last you long. Also before you buy your gauge make sure that you will actually be able to hook it to your car. What I mean is I bought an Autometer gauge which came with hard plastic tubing and compression fittings.

The problem was that the Hard plastic tubing wouldn't seal on a barb "T" and I simply could not find a "T" with barb fittings on the top of the "T" and a pipe tread on the bottom to accept the compression fitting supplied with the gauge. Fine you say, just get some vinyl hose; it will seal on a barb "T". Correct, but the compression fittings that came with the gauge were too small on the hose side. Again you ask: why don't you get a brass fitting with a barb on the end to attach to the gauge. Well they simply don't supply them in the mid-Ohio area. I looked everywhere and there simply are no barb fittings which fit the boost gauge (1/8" NPT).

OK then get a compression fitting that fits the gauge and the hose. Not so easy again. First of all, the vinyl hose collapses and doesn't seal in the compression fitting, and besides that it took me 3 days of searching to find a compression fitting that 1) fit the right size vinyl hose AND 2) fit the gauges 1/8" NPT. That's right I did find it.

I solved the collapsing problem by inserting a hollow plastic tube into the vinyl hose (actually it is one of a "T" which I cut off :). Then I could tighten down the compression fitting CAREFULLY and seal it without the hose itself collapsing. I still used RTV to make sure.

The point of all this blabbing to to make you realize that just because they sold you the gauge doesn't mean: 1) it has the parts needed to hook it to your car and 2) that they even sell the parts separately to make it work on your car. So the $15 I saved buying an Autometer locally was NOT worth it when I could have bought a gauge from any of our favorite net speed shops with the right parts already included. But remember: ASK WHAT CONNECTIONS ARE SUPPLIED.

Where should I mount it?

I used the standard A-Pillar Mounting Cup. You don't have to use one of these but it is the most common mounting method. OK here are the facts: NO ONE MAKES ONE THAT FITS. That's right even the cup which three (3) people told me was the best one to get at the shootout, still didn't fit right (they did admit that to me at the time also). Apparently all of the 2g cups are the same way. Have no fear though. If you file down about a 1/4" off the top of the cup it will fit very well. Other locations people have mounted their gauge was in the driver side vent. It looks nice if done right but no one sells a face plate so you will have to roll your own.

Where do I tap the gauge into?

This has been a frequent question on the digest. I have found in my searches that the best place is the fuel pressure solenoid (FPS). Which is under the hood on the driver side of the firewall (red box). From what I've read this gives the best results from the standpoint of stability (needle doesn't vibrate) and accuracy. The hose you want to tee into is the one on the passenger side of the solenoid (green arrow). If you follow it you will see that it goes to the intake manifold. Do not tap into the hose which goes to the Fuel Pressure Regulator (Drivers Side). Besides getting inaccurate readings, you may alter the signal which gets sent to the regulator and you DO NOT want that.

 

How do I get the boost hose there?

Anyway you can. Seriously though, most people seem to send it through the firewall via the steering boot. Have no fear . . . you won't lose steering if you cut this boot. All you need is a small hole to fish the hose through. I placed the hole at the 9 o'clock position in the boot. I then used an unwrapped wire hanger to fish the hose through. I did this by sticking the curly end of the hanger in the hose (this holds very well) and then fishing the hanger through the boot. If you bend the hanger right and fish it through carefully the hanger should appear somewhere reachable from the top of the engine (versus crawling underneath). Then just start fishing the hose around the way you want it (without the hanger :) until it is in place at the FPS. I made sure that the hose could not rub against the steering column as I turned the wheel by keeping it taught with wire ties..

How do I tap the FPS?

I used a simple tee. To avoid cutting the hose I slipped about a 2" piece of my vinyl hose on to the FPS and then attached it to the tee. The original hose which goes to the manifold is put on the other side of the tee. I then attached the boost gauge hose to the remaining part of the tee. All of the connections were secured with wire ties to ensure they wouldn't work loose.

How do I get the gauge to light up with the dash?

First things first. Don't bother trying to make the gauge dim. You can do it fairly easily (though not as easily as you might first think:), but it will not be bright enough especially if your like me and keep your dash fairly dim. Even on the brightest setting the boost gauge is barely bright enough even for me. Therefore I will be describing how to hook the light up so that it is only on when the dash board is lit and with no dimming control.
You shouldn't worry too much about what size wire to use since the gauge doesn't really draw a lot of current, BUT, better safe then sorry. 22AWG should be more then enough. You may even want to use an inline fuse but that may be over kill since the place we are taping power from is fused itself.

  1. There is a junction block that is just above your left foot above and behind the fuse box. B-66 is the wiring harness we are interested in.
  2. Pull the connector from there; it is quite hard to pull that connector. I cut my hand one of the many times I pulled it out. There is a "button" on the inner side of the harness (i.e. between B-66 and B-51). You don't "have" to pull the connector but it make the following steps much easier.

  3. Now you are holding connector B-66 in your hand and asking "now what". Well find wires #2 and #14 (black and green-white respectively). Tap into those with your trusty wire taps (or splice if you really must). It doesn't matter which wire you connect to which, but I put the two black wires together and the white and green-white together.

  4. Plug the connector back in.

  5. Turn on your lights and make sure your gauge and dash lights up.
  6. Turn your dimmer and make sure the gauge doesn't dim but your dash does.
  7. You're done. Turn your lights off and go to the next step

 

How do I hide the hose and wire as it travels to the boost gauge?

Well here I am going to have to assume you are using an A-Pillar mount. First of all route the hose and wire to the bottom of the dash where it meets the driver side door frame (near the fuse box). What I did was carefully pull back the rubber molding on the driver side between the frame and the dash (picture soon). You don't have to remove it. Just pull it back enough to stuff the hose and wire in there. Push the molding back in place and you no longer have to look at it. To hide the hose and wire as they passed into the A-Pillar mount I just cut a notch in the pod on the bottom near the back of the pod. This allowed the hose and wire to go into the pod with as little of them visible as possible. I think a better job could be done than I did so think about it before you do it. Hey I can't give you all the answers . . . that wouldn't leave you any fun :)

How do I mount the A-Pillar Pod

Good luck. The supplied mounting tape stuck to every part of my car except the A-Pillar molding, and YES I CLEANED IT SMART ASS :) So I decided to bite the bullet and drill holes. The stock A-pillar panel is only $7, so if you want to replace it to sell your car don't worry too much about it. Anyway, I drilled two holes in the mounting cup and then used it as a stencil to mark the holes for the A-Pillar. After drilling them I used some black automotive style push connectors (is this the right name??) to secure the cup. It works very well, looks professional and is removable. So get over it and drill some holes.

John Chin e-mailed me to tell me that Shoe Goo works really well also. He says that it is rather soft, is very sticky, and allows removal of the mount should you need to do so. The residue also scrapes/rubs off really easy as well. Let me if any of you try this.

I have since changed my mount to a Lo-Tek dual A-pillar replacement. This very sweet part replaces the entire panel and looks so stock it would fool anyone. More info on this will be posted soon so check back again soon.

Other Hints:

  1. Leave enough wire and hose in the mounting cup so that you can pull the gauge back out.
  2. Make sure you can disconnect the gauge from the hose and light. This way you don't have to deal with the hose and wiring if you should need to remove the gauge for any reason. Trust me its a good idea.

Acknowledgements:

The photo of the FPS was supplied by Tim Romero. Thanks Tim