Category: HyperMiata Build

Taking a detour for a bit, our tech day at the shop is coming up this Saturday and a couple days ago I realized that April 1 will be the one year mark to the day from when the car rolled in to the shop and the old engine came out. Decided the car should be on the ground and on display out front on that day!

So, the next couple days will be a bit of jumping around with random updates as I prioritize just the things needed to get the car on the ground.

Front Suspension

Clearly we were in need of some suspension to set the car on! Installed the following:
Feal 442 coilovers
Control arms with spherical bearings
Spindles with fresh hubs
R package tie rod ends
V8R upper rebuildable ball joints
Bauer extended lower ball joints

Notes…
– haven’t sorted out the front sway bar yet but don’t need that for Saturday.
– V8R front upper ball joints are tight until they lap in (takes a couple hundred miles). Correct assembly is to torque top cap down then back it off one “notch” of the lock ring and then install the lock ring. Reset the lash after first track day or 200 miles.

Setting the shock length/bump travel in the front (done with spring removed from the shock assembly):

Driveshaft

Installed the driveshaft with rear subframe and differential. Has to be done together as the Getrag has a long shaft on the flange to the driveshaft that the driveshaft slides over, so you lower the diff about 12 inches, install the driveshaft and then raise the diff with the driveshaft attached.

The CV joint on the driveshaft gave us some trouble, the CV wants to spring apart and has to be held together while installed. During first install something came unseated inside and the bearings locked up. Quickly evident as the drivetrain wouldn’t rotate because the CV was locked at one angle. Had to disassemble/reassemble the CV (and order the proper CV grease) and then reinstall. Everything is in and happy now. Forgot to take a pic.

Axles

V8R Stage 2 axles – first off, examining these in person they are very nice pieces.
Comes marked as one long and one short. Long one goes on the right side. The CV joints in these are packed with grease and the grease can keep the CVs from compressing fully so at first it appeared the axles were too long. Pulled them out and worked the joints around while putting body weight on them and they shortened up a lot and then installed fine.

Current state of affairs in the rear:

So, axles, hubs and spindles are in along with the V8R upper pro series control arms. What’s NOT in are my lower control arms complete with spherical bearings. The placeholders right now are factory arms with rubber bushings that were laying around.

This spherical bearing kit had some dimensional issues in some of the rear pieces. Unfortunately the company who makes the bearing kit has been working at a snail’s pace to make the necessary changes. As this kit is here for evaluation, this makes it hard to recommend it, but hopefully that stuff will get sorted out soon. As a last resort I can have the existing pieces machined to work right myself, but they assure me they’re working on corrected pieces. We’ll see, but for the moment these loaner rear lower arms will get the car on the ground.

Ran into one more hurdle in the rear. The beefy axles are larger in just about every dimension than stock Miata axles. Where the axles passes by the coilover, it’s very tight. There’s juuuuust enough clearance from the CV boot to the lower cup on the rear coilover, so that is OK but the lower lock ring on the coilover has a larger OD than the cup below it and that ring hits the boot:

Can’t have these two bits contacting with the axle spinning of course. I believe I have a solution figured out, Feal is sending over some parts that I think I can modify to make a custom low-profile lock ring out of. That stuff arrives Friday.

Fluids

Final thing tonight was getting fluid in the trans and diff since we’ll be rolling the car around.

Trans is 75W90
Diff is 75W90 + 4oz Limited Slip Additive. Sounds like snake oil to me (sarcasm) but OK we’ll follow the spec.

Got the USM (Universal Sensor Module) sorted. The USM is a four channel add-on to the Racepack digital dash allowing the addition of any sensors you want. Black box in the pic below:

The USM is why I finally took the plunge on a digital display. The original plan had been to add at least two more Accutech SMI gauges to the two I already had in the car so I could keep track of temperatures of all the various important bits. I realized I was heading down a path to having a very busy interior with a lot of things to try to keep an eye on.

The digital dash simplifies everything into one place where I can program warnings for each input and leave the dash to monitor things while I just drive. The dash pulls most of the engine vitals info I need right through the OBDII but the USM makes it possible to add the extra sensors I wanted and simplifies the wiring by transferring everything to the display via one V-net cable.

The sensors are already installed in their various locations, documented earlier in this thread. Now, on to wiring up the sensors to the USM. Here I’m using milspec /32 wire same as previously, but this time in 22ga twisted pairs. The twisting is a method of shielding the signal from interference. Frankly, you don’t need it for these types of sensor’s signals but here I used it because it helps keep things tidy:

Wiring within the USM box. The USM has a strain relief feature on the inlets which is a nice touch; tighten the outer nut and it clamps down on the wire to secure it in place:

The finished USM harness:

Mounting the box was done on the top/rear of the engine via a pair of simple brackets. Yes it’s tight back there. This is mounted to the engine so that all the sensor wiring can stay with the motor when it’s removed, just disconnect the single V-net cable connector:

With the box mounted we just need to run the V-net cable to the display. This could be done with one long cable that would need to pass through the firewall, or a bit cleaner version here that involves two shorter cables and a bulkhead connector:

Tidy!

The remaining wiring to be done was to tie in where necessary on the GM wiring harness. Most of this was coming through the firewall from the chassis harness – things like ignition switch, start button, lights, fan, drive by wire throttle, OBDII, etc.

I blasted through this and forgot to take all but one picture – V8R advised that the throttle pedal signal is very sensitive to interference, so for this I ran a 6-wire shielded cable on both the chassis and engine side:

The rest was just patching stuff into the existing engine harness. The stuff I added is all on par with what I did on the chassis side, but I’d love to re-do the entire engine harness in the future so that it is all up to higher standards. However, for now it’s a good working harness and this thing needs to be running!

All of the wiring interface from chassis to engine converges in the rear right corner of the engine bay. Everything is set up to disconnect from the chassis quickly/simply and comes out intact with the engine. There’s only four total things to disconnect, all located here: main bulkhead connector, v-net connector, engine ground and one M6 bolt that holds the fuse/relay plate to the firewall. Not trying to hide wires or tuck anything away, the goal here is easily accessible and quickly removable:

Switching gears a bit, this car will need some serious brakes… and they arrived!

Newly released 11.75″ BBK with Stoptech billet STR42 caliper. Ohhhh yeah baby, track testing can’t come soon enough!

Paired with my AP Racing J-hook rotors on aluminum hats:

Continuing on from the last post…

Here I’m beginning to loom the harness with a combination of the fiberglass braid plus short lengths of adhesive tube that will later be shrunk down over the ends of the loom to prevent fraying and seal the wires where the harness splits. You can see that assembling the loom requires a good bit of forward-thinking because each section often needs several more various pieces sleeved over it that will be shrunk down later:

Also in that pic is the bulkhead connector already assembled. That connector contains each wire that will pass from through the firewall into the engine bay, which makes it very quick and easy to disconnect the engine side of the wiring from the car so the engine can be pulled quickly without having to disconnect the wiring harness from the engine.

With beginning to pin wires into connectors we can cover the final piece of documentation; diagrams and pin layouts for each connector in the harness. When I began the harness build this sheet had blank spaces next to each pin, and I filled the sheet out as I assembled connectors:

Looming an engine harness is rather straight-forward as nearly every wire begins at a common datum (usually the ECU). Looming a chassis harness can be a bit more complicated since you have wires doing a lot of back-and-forth from switches to fuses to devices etc. In my case, I planned to put the fuse/relay box and a distribution block for power and ground on the passenger side of the transmission tunnel for easy accessibility. Also along this same area of the harness I had multiple breakouts for connectors that would go to the switch panel. This all made for a dense bunch of splits all at one point requiring a bit of work to tidy up and seal.

Here the wire is as condensed as possible and wrapped in kapton tape, ready for the Raychem ATUM to be slid over and shrunk to seal the breaks:

And with the breaks all sealed up:

After the loom is in place the last step is pinning the wires for the connectors. There are a few popular options for connectors with different strengths. I chose to use the common weatherpack and metri pack connectors for ease of service. Each wire has a seal that is assembled with the terminal so that the wire itself seals to the connector – the benefit here is this eliminates the need to seal the whole backside of the connector. In this pic you can also see the short sections of clear shrink tube that are put on each wire before the terminal is crimped on and will be shrunk over the labels afterwards:

Terminals inserted into connectors, connector sheet updated with which wire went in which pin position and each connector’s name labeled on the loom behind it. These are the connectors that go to all the engine and auxillary control switches that will be on the center console:

Similarly finished ends that go to the fuse/relay box:

There were a few other connector types used for the harness as well. Some were OEM connectors that had to be re-used, and then there was the connector that goes to the Racepack IQ3S dash. This is supplied by Racepack with an extra long pigtail made up of standard cross-link wire. I needed to de-pin the connector and then rewire it with the milspec stuff:

After some digging I found this is a Motec M800 34-pin connector. What do you know, ProwireUSA has pins for those 

Here’s the connector, new and improved:

For fuses and relays I chose this trick little combo box that takes both mini fuses and micro 280 relays. It uses metri pack seals and connectors:

Beginning to wire the box:

After much work, here it’s tidied up with service/strain relief loops on each wire:

The finished fuse/relay box and harness. The ring terminals go to a bus bar for power distribution and grounds. I put this whole assembly on connectors rather than build it into the harness so that it can be removed for service or additions without the need to take the whole main harness out of the car:

And after much more work, we’ve got finished harnesses, ready to go to the shop for install.

Main chassis harness (connectors to Racepack dash, OE brake pedal , GM gas pedal, fuses/relays, OBDII, all switches, tail harness, diff temp sensor harness) :

Power and ground to bus bars:

Tail harness (connectors to chassis harness to fuel tank, rear lights, and grounds):

Diff temperature sensor harness:

Engine control switches:

Racepack dash page toggle buttons:

At the shop, everything ready to go in. Oh, and this saves 10 lbs over the old wiring that was the already hacked and trimmed down factory harness:

Where to begin?? Fair warning, this is going to be lengthy. I’ll have to cut this down and simplify for some of the forums but here I’ll post all the details.

For the engine swap, the minimum wiring to get the thing fired up isn’t bad, particularly if you opt to have V8R prep the engine harness for you (I did). You could certainly retain most of the factory wiring on the chassis side and just tie in where needed.

However… I had a few things on the wish list for this car that meant there was more work to do.

Over the years of racing and modifying this car, the wiring has become a bit of a mess with things added, wiring cut to remove things, etc. etc. There’s even been a couple times in the past that I went to modify or fix something in the wiring and found it wasn’t the way the FSM says it should be – I had modified it at some distant time in the past and now I couldn’t remember how or why I did it.

To eliminate any potential for issues for the future, I decided the best approach was to remove all of the existing wiring on the chassis side from the car and start from scratch with good materials, practices, and documentation. This is also the most time consuming approach, but c’est la vie.

Step 1 through 10 of a big wiring project is all planning, long before any tools or wires come out. Drawing up plans, thinking about the systems you want to include and things you may want to incorporate in the future.

Here was my starting point, the electrical diagram for my new chassis wiring:

A diagram like this is the bare minimum to plan out a harness. But as soon as you go down this path, if there’s an issue in the future you can’t just open up a factory service manual to check the wiring diagram. None of that applies any more. The ease or difficulty of service/troubleshooting in the future now comes down entirely to the quality of the documentation you create. With that in mind, I took things a few steps further.

Working off the electrical diagram, I made a spreadsheet listing each individual wire that would be present in the harness – including the wire’s name/purpose and where each end terminates. Each wire is assigned a unique numerical ID. If you’ve ever tried to identify a certain wire in a harness you’ll know the struggle that can be – even with the multitude of wire colors that factories use you still end up with duplicates of certain colors and you end up having to break out the multimeter to test wires and sort out what’s what. By assigning each wire a unique ID and labeling the wire accordingly (more on that later) there is no guesswork left to do, just consult the master sheet and look up the wire number.

Here’s a screenshot of the top of the list. All in, there’s about 100 wires on the chassis side:

A great feature with having this in spreadsheet form means that if you stay consistent with the info you put in each cell then once the list is done you can sort the list alphabetically by whichever column you need. This was really handy during the build as I could easily switch between sorting by harness, numerical order, system, etc.

The remaining piece to the puzzle is knowing how to lay out the harness. The simplest method is to just start laying wires in the car from point A to B to get lengths, but I wanted to be able to build the harness out of the car and also have the plans so that everything is replicable in the future if necessary.

I took measurements on the car and then drew up the build plans:

Now, much of the above is a bit overkill. The key info there is the lengths between splits and the layout. The rest isn’t necessary but I like to be thorough – with this plus the connector diagrams that I show just a bit further down, I could build a matching replacement harness without any need to refer to the car or the original harness.

With the planning sorted it was time to start laying out the harness. I transferred the measurements to a 4’x8′ sheet of particle board with screws placed at each branch split for turning points. Progress shot with the chassis and tail wires being laid out:

The wires are labeled with their ID number on both ends. Here is where the thermal label printer got a workout:

All of the wires used are milspec /32 series with tin plating and very abrasion/temperature resistant insulation. This stuff is a big jump forward from standard cross-link OE wire in terms of durability and is also more conductive and lighter weight. It sounds obvious but the wire is the core of the car’s electonics and nothing else can make up for poor quality wire. IMO this isn’t the place to scrimp.

Most of the materials for this build came from ProwireUSA. Excellent source for professional/milspec wiring materials and the staff is very knowledgeable. They’re local to me but on the other side of town so I can attest to them doing a great job with order processing/shipping times as well.

With all the wires laid out the next step is looming things together. Time for some more materials! Here is all of the shrink tubing used in this build, in several various diameters.

Pictured:
Raychem RT-375; the clear stuff, for covering all the labels.
Raychem SCL; 3:1 shrink ratio, semi-rigid and adhesive lined for sealing bare crimps and also providing strain relief.
Raychem ATUM; massive 4:1 shrink ratio, adhesive lined and flexible
Deray V25; 2:1 shrink ratio, non-adhesive. This is similar to Raychem DR-25 but is a thinner (lighter) version designed specifically for motorsports.
Kapton tape (upper left); super high-heat resistant tape for wiring assembly. Serves as a barrier between the wires and the adhesive shrink tube so if you need to service the harness later you can cleanly cut the tube and tape off and you have like-new wire underneath.

Everything is tagged with its specs. You don’t want to accidentally use an adhesive lined tube where you don’t want it.

NOT pictured above is another loom material that I used in a lot of areas; resin infused braided fiberglass loom. It’s resistant to chemicals and can withstand a massive 1200° F. That’s quadruple what the good heat shrink tube can take, so this was my choice for the bulk of the chassis harness that runs along the trans tunnel and firewall. Overkill? Yep. I weighed the shrink tube vs. fiberglass loom and they are even, there’s no weight penalty for using either one over the other, except in cases of a run of just one or two wires where there is shrink tube available in smaller diameters than the smallest fiberglass loom. For wire runs of ¼” diameter and up it’s a wash.

It’s been quiet for a little while because I’ve been spending long hours building the wiring harness. I wanted to be rid of the hacked up factory wiring mess once and for all so I chose to take the long road and removed every wire from the car, because now was the right opportunity to take the extra time and learn how to build good motorsports wiring from the ground up.

For now, here’s a pic from way back on step 1 with wires laid out for the new chassis harness:

There’s still a bunch of assembly to be done before it’s driving (rear end, suspension, interior, etc.) but we’re close to first test start. All that’s left is wiring… not a small thing but I can feel it getting close!

Current view from the front:

First the hurdle. The factory oil filter setup is a cast aluminum housing that bolts to the left side of the block and extends up to hold the filter canister up near the fill cap. You can see the housing just forwards of the dipstick:

To run an oil cooler we need an inlet and outlet for the lines, but a traditional sandwich plate won’t work here because of the unique shape of the ports where the block and housing meet:

Conveniently, Keisler Automation has been working on a solution. Here is their oil reroute plate:

This plate has a pair of M16x1.5 ports to which I added the metric to -10AN adapters. It also has an ⅛ NPT port for a sensor, but I found its location to be too cramped beside the larger fittings (and the GM oil pressure sensor is M14x1.5 anyways) so after this pic was taken I plugged that port and put the sensor in the remote filter plate:

As I mentioned in the power steering post, the factory oil filter housing can’t be removed without taking the steering pump off because the factory bolts are too long. There’s no getting around this the first time, but when installing the Keisler plate I switched the two forward bolts to shorter ones – this makes it possible to remove/install the plate with the steering pump in place. I forgot to write it down but I believe I used M8x1.25x25mm:

With the in/out for the hoses sorted all that’s left is a remote filter and a cooler. For the remote filter adapter it was important to me for it to be mounted to the engine so that removing the engine requires as little disassembly as possible. I played with a few locations and came up with doubling up the filter adapter on the same bracket that holds the power steering reservoir. Here’s the filter adapter mounted up to that bracket (now powdercoated black) with the steering reservoir not yet mounted:

Here it is with the steering reservoir in place. The filter location ended up mimicking the factory location a bit. Oil changes will be a breeze:

Now for lines and the cooler. For the cooler I chose another Earl’s unit – same depth and length as the power steering unit but taller; 19 rows instead of 7.

Just as I did with the power steering system, in order to make the entire nose assembly quickly removable I chose to add dry breaks here. Staubli -10AN units for the oil lines:

Here’s the full system just before final install. I fit the dry breaks directly to the cooler so that the feed and return lines remained one line each rather than being split into two. Fire sleeves on the portion of the lines that are anywhere near the exhaust. The short line is oil plate outlet to remote filter inlet and the long lines of course go to the cooler:

Installed:

We begin with V8R’s power steering kit. Included are fittings/lines to replace the hard lines that run along the rack itself with steel braided lines as well as fittings and a high pressure braided line for pump to rack. The kit leaves it to the user to sort out the low pressures lines (usually rubber) and reservoir (I’ve heard the factory Miata unit can be used), so that blue 180° hose barb fitting is supplied for the exit from the rack.

I used everything above except the hose barb fitting because this car will use braided lines throughout.

Removed the old lines from the rack and spent a good deal of time cleaning the rack up. The power rack I got from a donor car seemed to have been competing for the coveted title of thickest layer of grime, but it’s shiny now.

Here’s the rack with the V8R lines added. Also pictured is the early version of the rack to cooler line I made which I later added the in-line dry break to:

Closeup shot. This bunch sit close to the pan once installed so best to leave them loose and adjust the angles once both the engine and rack are in place:

Pic of the power steering pump. The black threaded outlet goes to the rack which V8R supplies a fitting for (that’s what I’m holding in the photo). The port above that is the inlet from the reservoir. That port has a barbed end for a rubber hose in the stock GM form, but as seen in this pic I removed that and drilled/tapped the hole to adapt it to an AN fitting:

A note on the power steering pump pulley –
To remove the pump from the engine you must remove the pulley from the pump first. This took us a combination of parts from a rather comprehensive pulley puller kit, something most home garages may not be equipped with. Reinstallation of the pulley is equally difficult. I’d recommend leaving the pump on the engine unless you absolutely have to remove it. However, there is a complication if you’re going to add an engine oil cooler; to remove the factory oil filter housing you have to remove the steering pump first because the filter housing’s bolts are too long and can’t be backed all the way out with the pump in place. For shame, GM! Later, when I installed the Keisler oil reroute plate in place of the stock filter housing I swapped two of the factory bolts out for shorter ones and now the plate can be installed/removed with the steering pump in place. At any rate, if you need to remove the filter housing you’ll have to take the pump off at least once.

Now back to our regularly scheduled programming…
The next piece to the puzzle was the steering fluid reservoir. The reservoir needs to sit higher than the pump as it is a gravity feed. The pump’s position on the motor is high enough that there was a good bit of head scratching and lots of looking around at various reservoir options/shapes/etc. to figure out what to do. The solution I came up with uses a Moroso reservoir mounted directly to the top of the pump NASCAR style. This eliminated the need for a hose and guarantees good flow from the reservoir to pump. This reservoir is actually intended for power steering so it has the appropriate internal baffles.

I don’t have a pic of the reservoir by itself but you’ll see it in following pics. The reservoir had an AN bung in the bottom for the drain so with a couple fittings the pump was set up for the direct-mount:

To hold the reservoir in place requires a bracket. Always up for challenging myself, I decided to make it from aluminum. Here is an in-progress pic about 80% of the way done, just before tack welding the two halves I made together:

It turned out to be a funky looking little thing but it’s nice and light, piggy backs on existing factory bolts, and does just what’s needed:

Here it’s mounted up with the reservoir. Note the factory oil filter housing is still in place behind there, but that is removed later for the oil cooler:

The final piece in the power steering system is the cooler. Most cars doing any sort of performance driving will need one, you don’t want this system overheating and spraying flammable fluid around the engine bay. If you’re doing a more standard street setup with rubber lines there are lots of affordable cooler options with barbed ends built in. For this car I chose Earl’s 40700 cooler, which is a 13”x2”x2” unit, with -6AN ends. I erred on the small side to keep weight down but Earl’s stuff has efficient cores so I think it will do the trick. I’ll be monitoring fluid temp so I’ll know if it is sized well or needs to be upgraded:

Back when I was making the removable nose I made the brackets to hold the cooler in place. With the cooler, pump and reservoir all settled in all that’s left is to connect the dots with the lines. Embracing the idea of having the whole front nose section quickly removable, I picked up a pair of Radium -6AN dry break fittings for the power steering lines:

Long line below is cooler to reservoir, with the dry break junction fixed to the reservoir side. The short one is half of the rack to cooler line:

Here’s the other half of that lower line, I had already fixed it to the rack and didn’t want to remove it for the last pic. This section has a fire sleeve since it’s in the vicinity of the exhaust:

Final setup installed:

That concludes the power steering setup. Tomorrow I’ll write up the oil cooler system.

While waiting on the last fittings to arrive, this past week I’ve been working on wiring plans in the evenings.

Because race car I’m pulling the entire Miata harness on the chassis side as well and will make a new harness for just the essentials. For the record, if this was a street car with many more factory systems I would keep the factory harness and just add things as needed. But since that’s not the case, there’s some planning to be done here if I want to wire everything up in one nice clean harness.

The engine harness itself has already been set up nicely for my needs by V8R. They trimmed out anything unnecessary, converted it from auto to manual, added an OBDII port for me and extended a few wires at my request. They also fused anything that needed it and added a main relay. All that’s left for me to do on that side is carry a few voltage wires from the cabin/battery over to the engine side.

But, that doesn’t get me out of the woods. I still need to sort out a chassis harness which includes several systems like fuel, ignition, etc. as well as the Racepak dash plus the sensor module for the dash. I also need a cooling fan circuit, and I need to get the OBDII port and the drive-by-wire connector into the cabin. To make things easy to service/remove, almost everything will pass through a single bulkhead connector in the firewall.

One unknown I ran into during planning was the question of how much info the digital dash can pull directly from the ECU via the OBDII port. Anything the dash can get straight from the ECU saves me time and wires. The guys at Racepak couldn’t make any guarantees, they said you really just have to plug the dash into the car, start it up and see what data it can pull. Well that’s great except I can’t start my car yet – I need the wiring done before I can start it… but if I want to do the wiring all at once and not have to hack it up and add stuff later I need to know this answer before I do the wiring. Gotta love catch-22’s.

Sean had a great idea for a solution – rent a V6 Camaro and wire the dash up to it.

Turns out it can pull quite a bit of info. I don’t need most of it, but here’s the full list of what the dash is getting from the OBDII port – noteworthy items that I’ll probably be displaying on the dash in bold:

Fuel system status
Engine RPM
Vehicle speed
Calculated engine load value
Short term fuel % trim – Bank 1
Short term fuel % trim – Bank 2
Long term fuel % trim – Bank 1
Long term fuel % trim – Bank 2
Intake air temperature
Intake manifold absolute pressure
Timing advance
Engine coolant temperature
MAF air flow rate
Oxygen sensor Bank 1, Sensor 1
Oxygen sensor Bank 1, Sensor 2
Oxygen sensor Bank 2, Sensor 1
Oxygen sensor Bank 2, Sensor 2
Run time since engine start
Distance traveled with malfunction indicator lamp (MIL) on
Fuel pressure
Fuel rail pressure (diesel)
Fuel level input
Fuel type
Commanded evaporative purge
# of warm-ups since codes cleared
Distance traveled since codes cleared
Evap. system vapor pressure
Barometric pressure
Ambient air temperature
Control module voltage
Absolute load value
Command equivalence ratio
Throttle position
Relative throttle position
Absolute throttle position B
Absolute throttle position D
Absolute throttle position E
Command throttle actuator

In addition to the above bolded items, I’m adding temperature sensors for engine oil, transmission, differential and power steering fluid. These four will tie into a Racepak universal sensor module which transfers the data from those sensors to the dash via one cable. Between the stuff above and these four added sensors the dash should be able to keep an eye on everything important. I can set up warnings on the dash for any of these inputs, so I can focus on driving rather than worrying about checking gauges.

I’m disappointed that oil pressure isn’t on that list. The ECU monitors this, but it appears it doesn’t send that info to the OBDII port. I’ll need to wire up a second OP sensor or figure out if I can piggy-back on the factory sensor’s wires. Not sure yet on that front, but overall some good info gained and I can finish up my wiring plans now.

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Next morning update:

I spoke with Racepak this morning. Explanation for oil pressure not coming through the OBDII plug is that the Racepak dash can only read the “standard” OBDII PIDs. There are additional “enhanced” PIDs added by GM which are not required part of the standard/required OBDII data. HPTuners and similar can read those enhanced PIDs but the dash cannot.

Worst-case scenario is having to run a second OP sensor for the dash. However, I asked about piggy-backing off the factory sensor and they said because the factory sensor is a 3-wire unit, one of those wires should be a 0-5V signal wire and there shouldn’t be any issues with splicing into that wire to connect to the dash’s OP input wire on its harness. Then, it’s a matter of configuring the dash for that sensor which requires knowing the scaling of the factory sensor – info with should be in the factory service manual. So, sounds hopeful-ish…