Just finished wiring up a 94 with a '01+ engine harness for cleanness, and plugged in a pnp adapter harness and Hydra 2.7.

Coils according to the first post in this thread were backwards. You can't change the Hydra coil outputs within the software, they have to be wired correctly. Before I dig into the adapter harness to see if it's the issue, has anyone else experienced this? I have brown to brown/white, and brown/yellow to black/yellow.

Also, I went through all the work to install a TSE oil pressure adapter, SS line, and cut/drilled/tapped the upper hard line for a AN-NPT adapter, since I'm putting a VVT head on a 94 block. Did I do all that work for nothing? Am I reading in post #281 that I didn't have to do all that?

AFAIK you just use the stock VVT hardline, and it bolts up to the VVT block. The blocks are basically identical. But with different threading.

Also you can't change the coil outputs in megasquirt either.

Right, so the vvt banjo bolt doesn't just thread into the 94's tapered oil pressure sensor's threads does it?

The firing order I'm thinking of must be injection timing then.

Maybe not stock. But it should be very simple to tap it to straight threads. It also might be close enough to just thread in.

Not sure about the coil wiring but the VVT plumbing works just fine ,no modifications for my swap. I too used a 94 block with a VVT head. No leaks VVT works fine.

NICE. Thats what I wanted to happen. Did you retap the hole or anything?

No modifications , just screwed it all together using the factory parts. Fred

Curly, can you add that info to the first post of this thread? For future readers.

I can also confirm that the stock vvt oil hard-line will bolt onto a 94 block fine. If you are using stock coils with the stock bracket then you cNnot use the hard-line.

Stock 94 coils right?

I see you haven't floated away yet.

Yeah stock 94 coils.

Nope did not float away. Lots of rain and wind. Other then that we are fine.

Check your adapter harness. Uncle Humjaba confirmed his '95 wiring to be the opposite of what you have in post #160. It would also be highly illogical for Mazda to use brown/yellow as the trigger for coil 1/4 in 1990-1993 (verified in #156), then use brown/yellow as the trigger for coil 2/3 in 1994-1995.

I did tap the hole, from tapered thread to straight thread. No problems this way.

But, as an additional data point,
when the '94 oil pressure sender was in the '01 location in the hard line, I noticed oil pressure fluctuations when changing throttle settings. I corolated them to the vvt changing. So I plugged the oem sensor location, welded a AN3 nipple to the end of the banjo bolt, so the sensor would read the pressure in the oil galley and not the hard line. Ran a ss line to the same sensor mounted on the inner fender well. Now rock solid oil pressure indication at any throttle angle. Moral of the story is there is a slight restriction when the oil turns and goes thru the holes in the banjo bolt, enough to cause a slight drop in pressure that can be seen on the oil pressure gauge.

You essentially created a pulse damper with that AN3 line. So the pulses might be at the galley too. Wouldn't be able to tell without putting the sensor there.

Your mom is a pulse damper.

Oil is a liquid, and there for non-compressible, so a properly bled line and sensor will transmit every little pressure change. But your mileage may vary.

But a line might not be incompressible. Fuel is non-compressible, and yet we still have pulse dampers on fuel rails.

True, a line might be compliant, but with only 40-60 psi, a stainless braided Teflon line won't absorb the pressure fluctuations. The fluctuations are not pulsation, it is a momentary drop/rise when the vvt valve opens/closes.
A FPD is another animal, used for damping pulses from the injectors opening and closing, a decent description is found HERE.

I was was just stating a problem that I saw and what I did to cure it, take it for what it's worth.

Cool good to know. Not arguing here. Just thinking out loud.

Wonder if you can find one of these with the right threads.

https://cimg8.ibsrv.net/gimg/www.mia...6e4785ff58.png

Has anyone been brave/stupid enough to try this?

Are you sure the hole in the pump for the sensor is not threaded? I'm like 99% sure mine was threaded on my 94 pump.

I just went out & scraped the crap of mine. It looks tapped. I couldn't get an M6 to start in it though.

https://cimg4.ibsrv.net/gimg/www.mia...4a76fe48b1.jpg

Before I posted that I checked my 94 block, it wasnt threaded. The 97 block I have is threaded, well duh because there's the VR crank sensor there for OBDII cars. It should only be original non-OBDII car oil pumps that lack the thread.

It's a '94 block. The pan sealant sure looked factory when I pulled it, but I guess the oil pump could have been replaced some time in its life. I guess the moral of the story is check first.

Maybe I'm getting the split wrong? Maybe it was a mid year 94 change.

When you say the boss wasn't tapped, do you mean there was just a flat boss with no hole, or did it look like the one below. That's about the best shot I could get, and I still don't see threads. Like i said, I couldn't get an M6 in there, so there could be threads buried down in there.

https://cimg2.ibsrv.net/gimg/www.mia...21f7da5a75.jpg

Mine was flat, undrilled. From your picture it looks like you could run an M6x1.00 tap in the hole and it would work.

Tonight or tomorrow I'll go out to the garage and check the few oil pumps I have.

It's cool finding the little variants in mass produced things.

Along this same line of thinking, if I'm going to integrate crank sensory into a '94 block, I need to add a timing wheel. This is gonna change the stackup thickness of all the things bolted to the nose of the crank. Would I need to replace the pulley and/or boss with a NB specific equivalent? I have to think that something's thinner to accommodate for the timing wheel.

Edit: this answered my question. Boss changed in 96 when crank position wheel was introduced.

http://www.planet-miata.com/index.ph...ch-item&idn=89

Correct you need the 96 or new boss.

Tap the hole, I bet it's the right diameter for m6x1 threads. Start tapping it, once it bottoms out, grind the tap flat on a bench grinder. Then tap the bottom of the hole. Kinda ruins a m6x1 tap, but it's still useful for chasing threads and if you're careful creating new ones. Plus they're only about $10.

The hole should be drilled correctly for M6x1.0. We had to do this on some of the very early BE pumps (like 6 years ago) before Travis started tapping them all at our request.

Bottoming tap?

Yes if you can find one that'll work. Generally when you add coating, different tips, or other features like spiral flutes and what not the price goes up.

$1.60:
https://www.walmart.com/ip/WESTWARD-...&wl13=&veh=sem

$17.22
https://www.zoro.com/osg-spiral-poin...Q&gclsrc=aw.ds

Bottoming M6 taps are ~$7 at McMaster

I do not understand the purpose of a spiral point plug tap. A spiral point tap is made the way it is to propel all the chips forward, generally used in through holes only. Using one in a blind hole will lead to tears.

Regardless, the second tap Curly posted is not a hand tap and should not be used as such. It's made for highly rigid tapping machines, it'll break if you look at it funny.

When you grind the point off a tap you need to be sure it's done perfectly perpendicular to the threads, it's possible to have too many thread starts with a three flute hand tap if you grind the end off at an angle. It will shred stuff, quick. I do not like doing it, at all.

I'd just use a normal tap and find a slightly shorter bolt. 1.5x bolt major diameter is plenty of engagement for something like that.

Bottom taps aren't special or exotic. They are right next to the starter and plug taps for the same price. Grinding a tap flat with out the proper end chamfer is also stupid as it always leaves the last tooth or 2 super thin, and it usually breaks off in the bottom of the hole once it starts taking a chip load.

USA made M6x1 bottom tap for $7 shipped

Exotic bottoming tap just sounds dirty.

My current customer project is a customer who I built a motor for last year. He decided to have another shop assemble his car, including the VVT swap (motor is a 02, car is a '97). The shop doing the swap attempted to swap the complete harness, including chassis harness, from their donor '02 into his '97. When they couldn't figure out how to get it running, the customer asked if I would be willing to take over the project and get it figured out.

If you got this far into this thread, and you are still considering a full harness swap, I have one word of advice for you: Don't.

Just to update this connector info for this thread- many of the links in the above doc have aged out. However, Ballenger has a dedicated miata page that had every single connector I needed for this swap. The connectors are identified by their miata application, part number, and cross-referenced with their mating connector and pins. They also offer them all as pre-stuffed pigtails if you're like me and don't want to crimp pins. The whole experience makes for some very simple one-stop-shopping.

https://www.bmotorsports.com/shop/mazda_miata.php

stock ecu?

The stock ECU is plugged in, but since they only swapped half the NB fuel system in (front half), it never would have worked anyway. I'll be using an MS3 Basic for an 01-05 harness. It's not even the harness swap that makes it difficult. The NB fusebox is taller and requires a custom bracket. Still not sure how I'll mount all the relays that sit behind the NB fusebox. The headlights will never work again in this car since the motor relays left with the NA harness. No NB dash harness, so no wipers, turn signals, headlights, or HVAC. Thankfully the brake light switch connector appears to be the same. The entire fuel system is different, as I mentioned. Fan wiring is wrong, thankfully the SPM rad in this car can accept NB fans (shop lost his fans, so we'll replace). Keep in mind that this was sourced from a complete donor, so I have every relay/box that came with the '02, If you are buying a bare '02 harness and expecting to make it work in your NA, forget about it.

I wouldn't even try to estimate the number of hours of work it would take to make this work in a street car. I almost ripped the harness out and bought a new 94-95 harness to start over with (easier to get an ECU for), but the '02 harness was already in place and mostly plugged in, so it was faster to fab up custom brackets for a few things vs. re-strip the car and start over. It will still cost him a couple of thousand dollars in diagnostic and corrective work to get it running.

Lord almighty. Good thing its a racecar?

Electrical troubleshooting in the future is going to be fun.

It really is silly considering Ballenger carries all of the connectors.
I rewired my entire engine bay with freshly crimped miata connectors on the engine side and weatherpack connectors on the harness side over the course of a very lazy Saturday.
I guess all business is good business? Haha

I've stripped and wired an NB harness to work on an NA, with a 01-05pnp pro. It wasn't terrible, but I don't envy you. Wouldn't of been worth it, except the NA had no usable harness, and we had an NB engine harness. $250 in chassis harness later and it was running. With some alternator/kill switch issues, you might remember the conversation.

I've seen people use an NB harness in an NA before but they sort of ended up like they had two harnesses in the car.

I just got through wiring a 1991 CSP car 2002 motor with 99 VICS intake. basically reconfigured and re-connectored the harness to function like an NB and re-pinned the ECU connector Directly to a Hydra ECU connector. The only disappointment is following Street Prepared rules I couldn't strip all the unused crap out of it you can only change connectors or add wires as needed for other allowed mods per the rules. A couple small issues initially but I got it all sorted now and it looks clean.

Anyone in the LA Area? Need help!
 

Hello All,

I just did an Engine swap on my 97 miata with a 99 block. Evey thing is good except for the CAS/Crank position sensor and its wiring. I am getting no spark.

I am willing to pay anyone that is willing to help me get this sorted.

It is an FM2 Turbo kit with a Hydra 2.7 ECU - All programmed and ready to go.

Blew my engine at Willow Springs earlier this year and wanted to go 99 for the bigger head.

Hit me up and lets make this happen!!

Thank you

Where are you located? Have you tried a trigger test to see which sensor it's not seeing? It'll either be cam or crank. That or your timing wheel is on backwards or something. They're pretty easy to check though. Make sure all the power wires have 12v, all the ground wires have continuity to ground, and make sure both signal wires have continuity back to their respective ECU input. I think cam is BB09 or 10 and crank is BD14.

Hey Curly,

I am located Here:
https://www.google.com/maps/dir/33.8...3234513,16.48z

Honestly I am an IT Engineer but getting into Trigger Tests and signal wires is just more than I want to absorb atm. I Installed the whole turbo kit with my brother and programmed the ECU, but I am no mechanic. I do kow that the Timing wheel isnt on backwards... I can see you are in Oregon, I have family in Ashland (Shakespeare country). Want to come down for a weekend and enjoy some LA life? Food, room and board included, friend and mom have a house in Malibu and there is a couple hundred bucks in it for you or more depending on how hard it is to fix.

I have all the tools necessary, I may start digging into it this weekend, just finding the time to focus on it is the issue.

Let me know buddy, thanks. Regardless, I appreciate the input!

Hello

can somebody please point me towards the page (or post) that talks about the fuel system?

i browsed through a lot of the pages but cant seem to find it (trying to find update 1.05)

Is the general consensus to keep the return system or switch to returnless?

david

Pretty sure it's on the first page.

Keeping returnless would require a different fuel pump hanger.

99-00 rail with 90-93 regulator.

The very first post in the thread.

Duh....

I kept looking for the latest update at the end of the thread and reading it backwards...

Thanks for documenting all this!

Just finishing a swap at work, I actually prefer the 94-97 FPR, doesn't point the vacuum reference barb at the throttle body, and has a shorter barb so the fuel line can curve and clear the VVT actuator.

Huh. I have one of each, I guess I'll try them both & see what fits best. Any pics for reference?

Great thread! I have a couple of minor learnings I gleaned from my recent BP4W/VICS swap on my '94 which I think will apply to a VVT transplant as well.

1) This has probably been posted somewhere, but didn't see it on this thread. I didn't have an NB throttle cable handy, so my solution was to repurpose the upper mounting point on the TB cable pulley. I have no clue as to why the extra mounting point is there, and it requires a small mod in order to thread the throttle cable to it as shown below. 5 minutes with a dremel tool and I was good to go. This takes the ~1/2" slack out of the cable so it can be adjusted with the standard bracket. My other discovery was that the upper mounting hole diameter was the same size on my '94 TB but slightly too small on my '99 TB. This was easy to enlarge, however, a 1/4" bit is just the right size.
https://cimg3.ibsrv.net/gimg/www.mia...c1a410e87d.jpgupper arrow is to the upper mounting point, lower arrow is where to enlarge an opening for the cable.
https://cimg6.ibsrv.net/gimg/www.mia...e471af6097.jpgViola, room to thread the cable!


2) I didn't have an NB TPS pigtail, just a new connector so I was momentarily stumped on which wires went to which pins. I found a great explanation on deciphering 3-pin TPS connections here:
https://www.miataturbo.net/megasquir...23/#post649534

In conclusion... great forum, great thread and thanks to Andrew and many other knowledgeable contributors!

1) cruise control

Ah, of course!