Boost gauge problems... - PeachParts Mercedes-Benz Forum

ltrain300D · #1 07-27-2007, 07:23 PM

So I got the gauge in today.... VDO cockpit series, 0-15 PSI. I ordered it from e-gauges, and also ordered a 6' tubing kit. Went to the auto-parts store today and bought a T-fitting, but the hose I got with the tubing kit was 1/8" outer diameter, and the T-fitting I bought was for 1/8" inner diameter hose. So a quick trip to Home Depot and I got some 1/4" OD/.170" ID polyurethane hose. Get home, remove my old line going from the ALDA to the check valve (I think it is the over boost sensor - it is right up on the firewall by the brake booster). Install the new hose, cut it, put in the T fitting, and then run the hose to the boost gauge (had to buy a 1/4" tapered NPT fitting - looks like this http://images.outdoorinteractive.net/mgen/258124_d.jpg), and a coupler to attach it to the gauge. Start the car, zero response from the gauge. I am assuming the gauge works because when I blew into the fitting on the gauge as hard as I could I got it to read 1-2 psi.

Decided to try hooking it up to the back of the intake manifold but I don't know if I did it right, but I still got 0 psi on the gauge.

I am hoping the gauge isn't broken, but it responded to be blowing into it so I don't think that is the problem. I highly doubt I'm actually getting zero boost, the car runs fine.

Any ideas?

#2 07-27-2007, 08:34 PM

Quote:

Originally Posted by ltrain300D

Start the car, zero response from the gauge.

Drive it.

BodhiBenz1987 · #3 07-27-2007, 08:48 PM

Yeah ... boost won't kick in until over 2k rpm, under load.

Meanwhile, I still have a VDO gauge sitting in a box in the back seat ... bought it almost a month ago and have been SO excited to install it ... honestly haven't had time yet. Ugh. Weddings, illness, jury duty, overtime. Boooo.

Not to hijack the thread, but here's a question: Can I just cork the gauge into the line and get an experimental reading while holding the gauge in my hand? That is, I don't yet have time to actually install it in the place I've chosen (ashtray) with lighting and bracket and all, but want to play around with it ... does the gauge have to be "secured" onto something to get a reasonably accurate reading? I'll eventually fix it up all nice in the console, but will be a while until I get a good block of tinkerin' time.

LUVMBDiesels · #4 07-27-2007, 08:52 PM

Quote:

Originally Posted by BodhiBenz1987

Not to hijack the thread, but here's a question: Can I just cork the gauge into the line and get an experimental reading while holding the gauge in my hand? That is, I don't yet have time to actually install it in the place I've chosen (ashtray) with lighting and bracket and all, but want to play around with it ... does the gauge have to be "secured" onto something to get a reasonably accurate reading? I'll eventually fix it up all nice in the console, but will be a while until I get a good block of tinkerin' time.

You can just hook it up and it will work OK. I used my MityVac as a temporary boost gauge for a couple days. Just make sure you run the line through the firewall and do not try to just run it through the door frame.

ltrain300D · #5 07-27-2007, 09:04 PM

Ahhh, I thought I would get a response from giving it throttle in park. It's too late now, but I'll do it tomorrow... I also did some searching and found out the right way to connect it to the intake manifold. We'll see how she goes tomorrow... thanks for the help

ltrain300D · #6 07-30-2007, 10:54 AM

Ok, got the gauge hooked up again, drove it around and alas it worked. Didn't get out on the interstate, but took 3rd up to about 3800 rpm, and I could tell that the wastegate was opening just shy of 9 PSI (better than I thought), so when the boost controller comes in the mail I am going to get it for 12 PSI and leave it. Now I've just got to mount it in the right center A/C vent.... probably going to put a voltmeter or maybe even EGT in the left vent... not sure yet.

ltrain300D · #7 07-30-2007, 11:05 AM

Whoops, forgot to ask how I should go about removing the vent and such? Is it a big pain or rather easy? I just did some searching but I found a lot of stuff about removing the whole dash and hope I don't have to do that.

Mojool · #8 07-30-2007, 11:07 AM

where can one find a barbed adapter that fits into the hole in the intake manifold (where you take that plug out)...obviously HD won't have anything like that since they're all Engrish measurements.

I've been sitting on my VDO boost gauge for a month, too...

Jeremy5848 · #9 07-30-2007, 12:11 PM

Quote:

Originally Posted by ltrain300D

Whoops, forgot to ask how I should go about removing the vent and such? Is it a big pain or rather easy? I just did some searching but I found a lot of stuff about removing the whole dash and hope I don't have to do that.

1. Remove glove compartment
2. Reach in and push the rubber air thing out of the way.
3. Grasp the inner part of the plastic vent with your right hand from the inside and hold the outer part with your left hand.
4. Twist. The tabs will slide out of their grooves and the two parts will separate.
5. There's a thin wavy washer in between the two parts. Capture it for future use.
6. To reassemble, note how the tabs go and simply snap the two parts together. (Getting the rubber thing back on is another matter.)

Now you have a hole in your dash. I don't know what people are using as a gauge mount but some here have done it -- there are pictures on this forum.

Personally, I prefer the ashtray location as a better place for two or three gauges and I still have my center vents.

Jeremy

Jeremy5848 · #10 07-30-2007, 12:19 PM

Quote:

Originally Posted by Mojool

where can one find a barbed adapter that fits into the hole in the intake manifold (where you take that plug out)...obviously HD won't have anything like that since they're all Engrish measurements.

The hole in the manifold is probably tapered pipe thread. When Europe invented the ISO standard system, they "borrowed" the pipe threads from England. They may have different names but try a 1/8 NPT thread hose barb and see if it won't fit just fine. That's what I used for my boost gauge -- there are pictures on this forum somewhere.

See post #7 in this thread:

http://www.peachparts.com/shopforum/showthread.php?t=170191

Jeremy

TheDon · #11 07-30-2007, 12:21 PM

their is a fitting on the intake manifold that a short plug bolts into that will fit a brass nipple into.. I can't remember the size or threads.. I just went to home depot and tried a few and bought the one that fit.. ace should have something.

#12 07-30-2007, 05:24 PM

Quote:

Originally Posted by TheDon

their is a fitting on the intake manifold that a short plug bolts into that will fit a brass nipple into.. I can't remember the size or threads.

M10x1.0

ltrain300D · #13 07-30-2007, 06:09 PM

Lance (ForcedInduction) I have sent you a PM

#14 07-30-2007, 08:47 PM

Quote:

Originally Posted by ltrain300D

I have a 2 1/16" VDO gauge and I have my vents out - but how exactly do I mount the gauge?

Just for record in the case others might want to do it...

I removed the moving ball part of the vent and used the outer ring as a mounting base for the gauge. I bent the gauge bracket to make it point where I wanted and used a strong epoxy to glue the bracket to the vent ring. Then I just snapped it back into its hole and cut a small slit in the rubber boot for the boost tube and lighting wires to pass through.

ltrain300D · #15 08-01-2007, 02:56 AM

Well, finally got it all installed how I want it and finished, except for the boost controller which I am going to do tomorrow. I think it looks great, almost stock! I am very pleased with how it turned out, and also with the boost readings that I am getting from a turbo that is 260K miles old. I was expecting to see it top out at maybe 6 or 7 PSI but I am getting 9. I am excited to see what the extra 3 pounds of boost will give me (going to set the controller for 12 PSI).

I'll get pics up tomorrow as it was too dark to take good ones when I got finished tonight.