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bogle's 1991 mild build thread

I used VSS power because the foundry harness used it. I did think a bit about using power from the original igniter, but didn’t look into it too deeply, and figured there must be a reason the foundry harness used VSS power. I just wanted it to work with minimal struggle, so went with the known schematic. Def worth a shot using the OG power though.
FWIW, I messaged with foundry3 on ig today asking why he used VSS power. He said it was just convenience, and it was a design decision he made a long time ago. But it didn’t seem like there was any real reason. So not totally sure, the OG power source is probably fine. I guess I should move mine… maybe I’ll make a little patch harness to try it out. It would have been simpler to use that in the first place
Aaand looking a tiny bit deeper it seems the fat blk/yel power wire isn’t on a convenient plug in the engine bay. It looks like it comes from the fuse through the harness directly to each coil. So youd have to cut wires or make a little patch harness on each og coil plug. I think? Not 100% sure.

I guess if you wanted a more oe setup, you’d just need to get grounds to each k coil, then pass the signal wires through with a patch in place of the OE igniter.
Aaand looking a tiny bit deeper it seems the fat blk/yel power wire isn’t on a convenient plug in the engine bay. It looks like it comes from the fuse through the harness directly to each coil. So youd have to cut wires or make a little patch harness on each og coil plug. I think? Not 100% sure.

I guess if you wanted a more oe setup, you’d just need to get grounds to each k coil, then pass the signal wires through with a patch in place of the OE igniter.
Now it's getting serious. :) I've started a wiring diagram. I think I will use the OEM plugs with small patch harnesses on each coil to go from the 2 to 3 pin plug, kinda like the RDX injector adapter plugs. And run a ground wire to each coil, terminating at the ground pins on the 8-pin plug. This will allow me to ground to the OEM loop.
Do it! Curious to see how it comes out. I think the OG coil connectors use 1/4” blade terminals so should be easy to make a patch harness.
I was going to ask if anyone knew what the 2-pin connector was. Looks like a HX090, but I can't find a 2-pin version.
I took the car out for a long drive last weekend, the first time it’s really been out all year. I spend so much time fussing with it and thinking about its little issues, it was really nice to just enjoy it for a day, get a feel for it as a whole.

I went up through dry creek valley, which is obscenely pretty this time of year. The leaves changing on the vines — each grape varietal has a bit of a different color — and at 4pm, the sun is pretty low, making for a dramatic backdrop. I tried to take a couple pics at stop signs but failed to capture it with my phone, so a pro photo will have to do


Sonoma county is home to the car. If you’ve ever had a Dry Creek Zinfandel or Russian River Pinot you may notice a bit of spice. That’s the soot I sprinkle all over Sonoma county’s grapes with my rich AFR pulls. Adding to the terroir. You’re welcome!

Up past dry creek is Skaggs Springs road, 20 miles of smooth pavement, elevation change, and pretty high speed sweepers. There is usually no traffic except for motorcycles who treat it like a race track. It was the perfect place to really test out the short Quaife rack on some 50-70mph corners.

The short rack verdict is in (again): it’s awesome. It feels a lot shorter and effort is just right. The new rack has also totally, 100% eliminated the steering wheel shake I had at 65-70 mph. Double win.

I stopped to take a couple pics at an overlook at lake Sonoma.



It was dirty, though. One year’s worth of dust, and my fingerprints from opening and closing the hood 100 times. Sorry not sorry.


Dirty but fun. Days like this remind me how good the car is and how far it has come since the first drive. It feels good, sounds good, looks good. There was a moment when I was on a newly paved section of twisties, zero traffic, 6k rpm, a little sc whine, passing between redwoods and hills of red & orange vineyards, I got a little emotional. Just me and my middle-class F40 on a beautiful road with a beautiful view.
More driving and less fiddling! I went to another breakfast club rally the other weekend and had a lot of fun. I got some photos and drove the car like a crazy person. This one went from a winery in carneros all the way near Sacramento on some super twisty roads that I had never been on. One of my favorite things about these events is the pro photographers wandering around and camped out along the route.

This is now one of my fav pics of the car. It captures the feeling of the north SF bay area pretty well.


Chased by 5 red alfas all from different eras, they never had a chance :p

Another roller with minimal derp face


Next to a 1982 turbo euro capri. I didn’t know what it was when I parked. I guess they only made 150 of them.

Also I love watching people check the car out.


In person the car looks super wide, even with stock fenders. I guess you all know that, but it really doesn’t come through in pics, imo, and it’s tough to capture with the camera. A long focal length and a highlight on the rear fender seems to do a decent job tho


And a pro photo from a film camera


I was chased by an Aston Martin with a Rudolph nose on the way back. It was goofy every time I looked in the mirror


A bunch of other stuff behind me


And a few of my other-car shots




I also brought the film camera, but the film is out for development. More pics later
I took some film pics with a camera I’ve had since college (pentax k1000 + Kodak 200). I only got a couple of the car




There was a superformance GT40 there. It was definitely the hero car of the day:



450-500 hp 302 and 2200 lbs


Air cooled Porsches don’t give me any feels for some reason, but this one was cool. I loved the color


And some more euro nonsense, clean euro nonsense tho

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It’s true, definitely a dreamy ethereal vibe. And kinda fun that it makes you work for good shots. Pretty much everything looks good out of the a7r, but the K1000 takes some energy. Not unlike an MT car I guess.
Nice shots. Great stance on the nsx!
Merry Christmas! I finally got that haltech:


… but it’s for the civic, ha. My old EF has been floating around between spaces at my parent’s places for the last 15+ years. Every time they move it, I get hassled because it doesn’t run. Right before I moved to SF, I had changed a bunch of stuff (fuel pump, injectors, and more). I was also testing new code in the ecu, and I never finished. Definitely a recipe for not knowing where the problem is. Anyway, I’ve told them I’ll get it running this summer. Debugging my old shitty code is not on the agenda, so the haltech.

Here’s it’s ~5th home. They keep moving it to further out out-buildings, but fortunately always indoors.


It didn’t make sense for the civic to get a new ecu before the NSX, of course. I finally got that SoS link:


I’ve been going through the basemap setting everything up. There are a few tables of injector settings that are more complicated than 2d dead time, and they’re all set up for ID1050x injectors. Rather than kinda guessing on the tables for the EV14 550s I have, I figured it’d make my life easier just to use the 1050s, so I got a set:


SoS was unwilling to give me a basemap with fuel / ignition tables from a tuned sc car. It’d be nice to get as close as possible out of the box. There’s a guy on ig I interact with who has a similar setup tuned by SoS. He said he’ll share his map, so hopefully he comes through. In the absence of that, the plan is to port over the boost parts of the ign map from the AEM as a starting point, which are more conservative than the basemap I do have. Then of course get it running super well in vacuum, and probably take it to like shad for a proper WOT tune.

Belt slip is a problem with the supercharger. It tends to slip at higher rpm and shows as the boost bleeding off toward redline. An extreme example with a super loose belt to showcase the issue, it starts at 9 psi and bleeds off to 4.5 psi up high:


It’s been tricky to have minimal slip without over tightening the belt. I use a gator back / continental elite belt, but it still slips.

There’s a company called ZPE that makes grippy pulleys, so I sent them my small (89mm) 9.5 psi pulley and had them build a Griptec pulley:


It’s got a grippy pattern on the ribs:


A closeup:


It’s 3.5”(89mm) measured to the top of the ribs on the pulley. If you have a whipple ctsc and want one, you can order one from them by telling them the offset (0.695) and order number (924286). You can specify any diameter you want.




Is it better? Yes but not totally fixed. Here’s a pull. It seems to be pretty steady at 9.5 psi until about 6k rpm, then it drops off to high 8.x psi.


This pull was after several hours of driving, on the way home from the rally from the previous posts. With this setup, on that day, the car felt as fast as it ever has. Maybe it’s the cooler weather (70F at the TB inlet)? It feels quick AF, a lot of tire spinning if I’m not careful.

I’m still super paranoid about belt tension. It’s probably on the loose side, running about 110 lbs tension when hot. I can still twist it past 90 deg, which is the usual test, but would prefer to be as loose as I can get away with.

One downside to any slip with the griptec pulley is tons of belt dust. The alternator even after one short drive is pretty dusty:


Maybe the gator back belt is not a great option for this pulley? I got a couple other belts to experiment with, hopefully less slip and less dust.

In any case, I had griptec make me 2 other pulleys, a 3.7” (94mm) and a 3.9” (99mm)


The middle pulley should be about 7psi, and the large one should be about 4.5-5psi. I badly want to get the car on the track next year. 9.5psi is fun on the street, but unnecessary for a track outing, so I’d run the lowest boost possible.
Power bits

I’ve been slowly trying to improve the power situation under load. To recap, I’ve been sort of chasing a voltage drop at high load & high rpm for the last year or so. At its worst, the ecu was reading about 12.1 volts min at 7500 rpm and full boost. Sometimes the ecu would cut out / restart and my guess was that it was sometimes dropping below 12v, likely an aem series 1 quirk. The drop is probably normal but I thought maybe I could still improve it by replacing some obvious parts.

I replaced the ignition switch. A ton of circuits run directly through the big black / yellow wire coming off the ignition switch. On my OG switch, the black yellow and black white wires had been spliced and run through an immobilizer on my alarm.


Seems like a pretty hacky way to do it, so just replaced it and am not running the immobilizer right now. Side by side, old vs new:


The second thing was the alternator. The supercharger requires use of a 92-96 prelude alternator, the most common are only 80 amps. I thought under load with the wmi and everything, maybe the alternator couldn’t keep up. I previously tried a singer high output alternator, but had nothing but problems with it. Well it turns out there is a factory 90 amp alternator option on the Si / H22 variant of the prelude. The denso part is out of production, but Bosch makes one (part number AL1264X) and rockauto sells it, so that seemed like the next best option:


It comes with a 6 rib pulley, and our cars are 5 rib, needed a new pulley. The obvious fix is swapping the pulley from my 80 amp unit. The 80amp unit has some black belt dust near the pulley indicating belt slip. It could be good to have a grippier pulley, so I had a griptec one made. I sent them my stock pulley from the 80 amp unit and they made this out of stainless steel.



I didn’t specify a material, they thought stainless would be best.

More grippy grips:


And installed:


Did all this help? Yeah, a little. It also contributes to the belt dust problem. Power wise, it seems like I picked up a couple points. It now doesn’t drop below 12.4v even under full load.

But the dumb ecu still cuts out every now and then. It seems to only do it after driving a while, like when the box is warm or something. It even cut out once after hitting a pretty bumpy bridge expansion joint. 3k rpm with no voltage drop, so it probably isn’t a voltage drop issue.

After some reading, this cutout isn’t so uncommon. There are a number of threads on Supra and evo forums with the same problem. It seems like some aem series 1 ecus have loose eeproms or loose cpu chips. Yay quality.

It will be super interesting to see if the new Link sees the same drop. My guess is no, the new injectors will be higher ohm, and they’ll be open for shorter pulsewidths. I’ll wager it stays in the 13v range under full load, but who knows.
It’s alive, part VI

The link ecu is in and it’s running. I haven’t had a chance to drive it yet, but: It idles! All the sensors work! The can bus works! The base timing is set!

For reference, here’s the ecu as it comes from SoS. The 2 big plugs hanging off of the ecu are for accessory things: widebands, fuel and oil pressure sensors, etc.


In the before times, there was an aem series 1, sweet wood block and all:


Into the after times with the link ecu installed:


Running and its idling smoother than it ever did with the aem:


I even managed to get the CAN bus emitting all the data and the navpod displaying everything. Yay for modernish tech where I can have the laptop connected and have the navpod work at the same time:


There were a lot of little projects getting here and, of course, not without nonsense. I’ll go into a few details in later posts.

Next step is to actually drive it, but that’s probably a next weekend thing. It’s super rainy here, don’t want the car to melt, you know?
Link ECU continued

As usual for a big change like this, the install had a number of hiccups. In general, the link ecu seems really flexible, and the SoS stuff made things a lot faster than starting totally from scratch with a universal ecu.

But SoS has a few bugs to work out. I wonder if they mostly install and tune these themselves and don’t have so many randos like me DIYing them.

I had some trouble with the unit itself, the docs were missing things, there were a few ambiguous instructions, and even a couple wrong areas. Also the basemap for a 91 had a few things setup for drive by wire and ethanol that took a bunch of trial and error to sort out. A bunch of small issues together with learning the link software, everything took a long time to get through.

To SoS’s credit, I’ve been going back and forth with them. They already updated the docs for some things, and they know about the basemap issues.

Some of this would have been fixed with a known-working map from a car they tuned. I asked (for the 3rd time) for a map from a tuned 91-94 car, but they ignored the request. People are so cagey about sharing tunes which makes zero sense to me. Once tuned, mine will be open source…

Replacement ecu

A keen eye may notice in the last post that the unboxing ecu and the installed have different color sockets and a different label.

Right after unboxing, I was curious how they had wired things, and which chassis-harness wires were connected / not connected to the actual link box. In my little check, I noticed that the vtec plug wiring was not the same as the chassis F plug. They used a couple pins that didn’t have wires on the chassis harness. The bottom wires here should be on the top left pins:


I emailed them and they said, oops, it handn’t been wired correctly. They sent me another one and I returned the original one. Also good cause I couldn’t get the original to properly mount up to the factory holes


The new one was wired correctly at the F plug and easily mounted up. Yay


First thing on the list was wiring. In the last setup I added fuel pressure, oil pressure, and oil temp sensors and I ran them through factory wires like EGRL, ignition adjust, and throttle angle. I had moved some pins around to use open inputs on the aem.

The SoS link uses two 16 pin plugs for open inputs and outputs, so I had to re-pin a few things and build a little harness:


The small side connects directly to the ecu pins for the factory EGRL, ignition adjust, and throttle angle wires I’m using to run the fuel pressure, oil pressure, and oil temp sensors. The factory ecu uses TE/Amp multilock connectors, so depinned ecu pins snap right into an 040 multilock connector, no cutting required. That big fat plug on the other end of the harness runs into the SoS harness

For the Link ecu, a fuel pressure sensor is basically required. The ecu uses a “VE modeling” approach. The fuel table is filled with volumetric efficiency values from 0-100%. Then it calculates injector pulse width based on injector size, fuel pressure, and a volumetric efficiency from the table. Super glad I already had it wired in and it was only a matter of swapping some pins.

The wiring instructions above were one of the ambiguous bits of docs. It was unclear exactly which pin on which plug was “A”. They say female, but it actually was the plug with the male pins, the plug on the ECU side. I ended up wiring everything backwards at first :/

I made a new oil temp sensor harness:


It passes through the rear header area between the runners. It gets hot, the last one had 1200F sleeve over it, but the insides still got hot enough to melt the inner 105C sleeve, oops


The new one has fire sleeve over the hottest part of the run, 1200F sleeve inside that, and higher temp tezfel wire, so hopefully it’ll last.

And the last bit is the widebands. The sos link uses the AEM inline widebands and reads them over the CAN bus. That was cool because I already had them setup and wired into the CAN bus. I ended up rewiring them to use the Link-supplied wideband power. I also used this cool SoS bracket to hold them. No more zip ties!

I'm so glad to see this progress. That old AEM clunker was causing you more problems than it was solving! Looks like SOS needs to work out a few more bugs, though.

I saw in your sale thread that you're using ID1050 injectors. Since you have a supercharger, I'd think hard about switching to the RDX, as they are OEM and designed for FI. The atomization is real and the modern multi-hole injectors are just better technology.

Also, I ran my oil temp wire along the rear head on the path of the oil pressure switch wire. This keeps it well away from the rear headers.
Thanks! Yeah can’t wait til it’s all tuned and I can lay into it.

The RDX injectors would be maxed out, or i’d need to run high fuel pressure. With the RC 550s (which flow tested at 575) they’d run at just under 70% duty cycle full boost WOT. I was honestly worried about headroom on the other ev14 550s after they flow tested at 510, so def wouldn’t want to go any smaller.

The IDs are kind of the gold standard right now, with an apparently good spray pattern, reliable, and good at low pulsewidths. ID doesn’t make any smaller injectors anymore because “they don’t have to,” the 1050s are supposed to be great, even at lower power levels

Noted on the oil temp routing. I can look into a better routing situation. I’m running it over to the ign adjust wires, and I’m using a stock wire stay (probably for oe o2 sensors) hanging off the rear head. The wires themselves were fine inside the old harness, so hopeful the new harness with double heat protection is all good. It may be that the harness is subjected to just over 105c to melt that sleeve on the previous harness

Also good news: SoS agreed to share a tuned map, yay!

I’ve been going back and forth with them on iacv setup. The basemap was not setup for an iacv, so I had to manually set it up. Their suggested output for the iacv doesn’t work for me, so I moved it to another output and it works fine. They don’t love that their suggested output doesn’t work, so were willing to share the basemap.
Oh wow, I didn't realize the CT blower used so much gas! Makes you wonder what was happening with the OEM 270cc injectors that Shad goosed with high fuel pressure. 100% duty- a firehose of gasoline?

When I had my GT-R the ID1050's were one of the go-to injectors and they are very highly regarded. I ended up with the ASNU 1050's, but that's just because it's what my tuner preferred. I would have just as well gone for the ID. For some reason, they tend to idle well compared to other "big" injectors. I'm sure they'll work great for you.

Just wanted to say this is one of my favorite threads on Prime and I'm always excited to see updates!