Omori Boost Gauge Installation

[tw2]

I have just finished installing my Omori boost gauge I purchased from PrimeDriven. Or at least the gauge itself and wiring, the vacuum hook up will come later. I also got the dash light LED's to put in at the same time (also purchased from Prime). There are no shortage of threads on this but almost all of them are now devoid of pictures. I will post this on mr2.org.nz and mr2oc.com for longevities sake.

https://primemr2.com/collections/gauges ... or-cluster
https://primemr2.com/collections/interi ... b-lighting

This was done on a JDM 1991 (equivalent to USA 92 model year) with 3sge that comes with the same volt meter as the 5sfe cars. Note that the instument cluster pin outs, wiring and layout is not the same in different markets and the USA and JDM are quite different.

There appear to be at least two different types of Omori gauges. The “JST” branded ones seem to be the same but there are ones that have a white needle. This is important because the needle of the white needle variants is longer and will touch the black bezel requiring... something. If I had one of these I think I would get an icecream stick to put underneath and a very sharp knife and shorten the needle 2mm. I have seen others grind out the black bezel but I personally don't think the outcome always looks the best.

This video has a lot of pointers and helpful information https://www.youtube.com/watch?v=kPKZAmyJv2c

This one is good for LHD people https://www.youtube.com/watch?v=3OLf9MQys0k

RHD cars are pretty easy to dismantle. Pull out the shifter surround, remove the large stereo trim piece that has the cigarette lighter and hazard lights button in it. Remove the large under dash piece. Next in order is the piece that goes across the top of the steering column below the instrument panel and encorporates the right air con vent. This one is a pain to gently move out of the way of the steering column clam shells. Removing the clam shells would make it a lot easier but they often explode into a million pieces at this age as the ABS plastic goes brittle (yes I have visited the plastic welder with it in the past). If you can get that out then there is only the thin piece that goes over the top of the instument panel as seen in the videos- two screws and two clips, use a plastic pry tool to avoid scratching it. It is mostly the same as the LHD cars.

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[tw2]

There are three plugs on the JDM cars in the back of the instrument cluster. You have to stick your hopefully thin arm through the aircon spaces to grab them out. Luckily due to their design they come out somewhat easily as you can't see anything. USDM cars have four plugs I believe. If you have a speedo cable this will have to be unplugged. Mine had one simple plastic clip to push and it came out easily. You will get grease all over your fingers.

Remove the plastic clear cover carefully as in the videos, same with the black bezel. The Omori gauge comes with a “case” which has to be pried off. Go around it carefully with a screwdriver until it comes off. This is not used. The next part is preparing for wiring. Some people run the wires to the radio/cigarette lighter or other sources. This is easy but not neat and is also uncessary. All of the feeds you need are actually located in the instument cluster, battery, switched 12V, ground and illumination. The issue is the different markets and turbo vs N/A provide a lot of variations.

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[tw2]

First is the exit from the cluster for the Omori wires. Some drill a hole in the top of the cluster. I liked the idea of them exiting out of the back of the cluster through the bolt holes for the volt meter. They need to be drilled out to fit the wires through. The loom to be wired up needs a 5mm hole. The plug for the boost sensor needs just less than 8mm hole to fit through, I used an 8.2mm drill bit. First cut a small amount of the green “circuit” layer away from around the holes. You don't want to catch it with the drill bit or cut through anything other than the copper immediately around the holes... or you will be fkd. Next make a loom to wire up, you will be ditching 95% of the loom it comes with as it is way too long. Measure carefully and cut to approximate size. Make sure any crimping, soldering etc is all done in the correct order. Its always fun removing a perfectly crimped lug as it won't fit through your predrilled hole.

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[tw2]

For the illumination white wire, it connects to a 12V source. A lot of people complain the LED is way too bright. I purchased a 510 Ohm resistor and put it in between the white wire and my illumination source. I have seen people use 270 and 470 Ohm also. My guess is that 470 would probably be about right. The 510 made it slightly darker than the LED's in the cluster. Resistors can be installed either way around, they don't care. LED's do care so check them before you put the car back together!

For the placement of the gauge, I found when placed in the cluster there was only 1-2mm movement side to side and up and down. When the black bezel was placed over it, it moved into the only position it naturally wanted to go to and there was zero movement. As such I didn't glue it like others have. Another member commented that the black face can rotate on you if you are not careful. It has a small notch to sit in place but can fit at 90 degree rotations. The 30mmHg should be straight down.

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[tw2]

Wiring is a bit challenging. The USDM turbo BGB I had was only moderately helpful- only some pin outs were the same. Be careful which direction they are numbered, check all wires manually and test them. A 12V door bulb with a long wire attached and a multimeter will help heaps. The easiest place to start with the N/A cars is the ground and switched 12V. Both of these are part of the volt meter. We just destroyed them when we cut the green wiring and drilled the plastic but they can be traced to a separate screw each futher down the board, in this case over the tach. Just follow it carefully and check with multimeter. IG+ is the switched 12V on mine and SE is the ground. All cars seem to have a ground at B1 connector (large brown wire) so check it is continuous with this.

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[tw2]

Next is illumination. Any of the 4 main back lights will be fine. The are all wired together. For me B6 was the 12V power supply for the bulbs and it ran to the top of each bulb. B7 was the tan coloured wire that was the ground for them. You can confirm which is which by running a spare bulb as a test circuit to a known good ground with the lights switched on. As the wires are very thin I found I could simply jam it under the bulb which twisting it in. This made a VERY tight and strong hold on the wire. I was not keen on soldering anything.

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12V continuous was the most difficult as almost everything is switched. But the door open light is always available so this seems a good place to start (and the only one I could find). Mine was located in A6 and was a plain red wire. Your bulb and wire will make it easy to test this. Put everything together and crimp on some small lugs. Be careful as the wires are very thin and it is probably easy to ruin both plugs in the back of the gauge.

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[tw2]

I pulled the boost gauge sender to the drivers (right) side and I will run it somewhere useful. It isn't long enough to make it to the engine bay so a vacuum line might need to be run into the cabin. Otherwise in theory the brake vacuum line in frunk should be fine to use but finding the correct T port might be tricky.

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[Benckj]

Nice job and good clear write-up on the mod. You should offer a service to replace gauge if owners send their cluster into you. I took the easy option and installed an EBC in cab with digital readout. One of the advantages with EBC is having control in cab and display flashes when it reaches max value so nice to keep track of value reached. Does Omori have a function to briefly display max value?

[tw2]

Thanks Jim. No it is just a simple gauge, no extra functions. I wanted everything to be very stealth. I don't think I am good enough to offer a service but hopefully it helps someone. Now I just need to add some boost somehow....

[thorns]

Definitely looks the part and saves having to drill/mount gauges in the cabin. Looks factory at first glance as well.

[tw2]

Part 2 - actually hooking it up. I chose the brake vacuum line so I didn't have to run anything through the cabin. It is also a 3/8" hardline from the intake manifold forward so should give a pretty fast and accurate response. I wanted a wide T- piece so as to not occlude the vacuum reaching the brake booster so that ruled out any crappy plastic multi-size t-pieces that come with some kits. I went with an aeroflow 3/8" (9.5mm) fuel pressure fitting with a 1/8 NPT port for a fuel pressure gauge. I used a 1/8 NPT to 3/16" barb fitting and some thread sealant.

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[Benckj]

I’m not keen on using brake vacuum line for boost monitoring. Using a larger line actually dampens reading rather than small semi-hardline supplied with gauge for fast response. Probably ok enough for a gauge but would not use to control. Best to connect directly to plenum so pressure is what engine is running at.