In reply to DeadSkunk (Warren) :
The bad threads are at the entrance of the crank, not the back of the hole. I have to go past the bad threads to get to the good threads.
This is what I ordered:
In reply to DeadSkunk (Warren) :
The bad threads are at the entrance of the crank, not the back of the hole. I have to go past the bad threads to get to the good threads.
This is what I ordered:
In reply to PMRacing :
OK. I misunderstood where the thread material was. That tap will work fine.
If they're threads deep in the crank, I'd use a bottoming tap to clean up as much as you can. For what it's worth, most of the load is carried by the first couple threads, so those threads are probably not doing much work. A little blue loctite for good measure and send it.
Edit: I see the discussion that happened while I was typing. I see your concern now. I'd probably try your regular tap first, just go really slow and stop if it feels bad. If that happens, I think you'll want to grab an ID thread file. The danger there is that you may taper the threads, so the goal would be to just ensure you get the threads clean enough to send the tap in.
https://www.amazon.com/General-Tools-177-8-Metric-Thread/dp/B0017R1DOM/ref=mp_s_a_1_3?crid=2THR6XGWZ9RK9&keywords=metric+thread+file+1.5&qid=1682255508&sprefix=metric+thread+file+1.5%2Caps%2C102&sr=8-3
DREMEL FTW!
I was able to Dremel out the first couple rows of threads to get rid of the borked ones. Ran the tap into the good threads and the bolt goes all the way in by hand. PHEW!
Well, I got the car running again! Woohoo! I'm just going to stop with the VVT install for now. I need the car running for track in a couple of weeks.
Now, there is another issue that I need some advice on. I have an '02 engine in a '97 chassis running the stock '97 ECU. I have a code for a bad crank position sensor. Turns out the trigger wheel on the '02 and '97 are different. But from what I've read, the '97 wheel is only used for misfire detection so the car will still run, just with a code. It smells like it is running rich, however no other codes.
Now, for the VVT, this is how I'm wiring it using the stock ECU.
In theory, the only thing the VVT controller needs from the factory harness is the signal from the crank trigger wheel (this is what an engine controls engineer friend of mine has determined). Everything else comes from the VVT controller box and ground. DIY Autotune does not have instructions for wiring to a stock ECU, only a stand alone.
Questions: 1. Do I need to swap to a '97 trigger wheel and crank position sensor? Again, from what I've read the '02 Crank sensor and '97 crank sensor are different types and may not be powered the same.
2. Does the wiring layout I'm using seem to be correct for a stock ECU. The Crank position sensor does not need power from the box since it would be coming from the vehicle's wiring harness and it is also grounded through the factory harness. I only should have to tap into the signal wire.
Thanks for any advice!
First thing to check on that crank sensor is the air gap. I haven't looked into compatibility, but the most common problem with the crank sensors is too large a gap.
Pretty sure all the NB motors used a returnless fuel system. No idea if/how that would effect a stock NA ECU...
In reply to calteg :
I modified the NA fuel rail to fit. It runs a return system.
Keith, I'll check the gap but I set it about 0.8mm within spec. It may have been bumped so I will double check.
In reply to calteg :
The difference is that the NB runs a consistent fuel pressure instead of it being tied to manifold pressure. That's going to affect the fuel tables, so you'll definitely want to keep the "correct" FPR reference according to the ECU.
With regards to the different crank sensors, maybe check with the aftermarket ECU crowd and see if there's a different setup for an NA trigger and wheel versus an NB.
The first track day of the season was on Tuesday. I got 1.5 sessions in. First session was really just bedding in new pads. I didn't push too hard. Next session was doing some instructor training so I wasn't really concentrating on going fast and more on being a novice student and working with a new instructor candidate. However at the end of the session the car sounded off. By the time the cool down lap was over the car had no power. I knew the spark plug wires didn't fit too great (NA plug boots are larger diameter than NB boots and I had been trimming them to fit in the valve cover. When I got in, I found that two plug wires weren't on tight. OK, no big deal. Re-seated them and thought nothing of it. Until I started the for the next session. The car was still not running on all cylinders. Long story short, I found that the 2-3 coil was dead. Luckily someone at the track had a spare so I could get home, but I was done for the day. I knew this was going to be a possibility due to my locating the coils over the header. I do have a heat shield over the header, but it wasn't enough. This week I ordered new coils, some heat reflective tape, and a starter blanket. I modified the starter blanket by wrapping it around the coils, poking a couple of holes so it would mount with the coil bracket, and cut an opening in the top for the spark plug wires to come out. Here's the result. Hopefully no more cooked coils. And yes, those are 3 NA plug wires with the #4 plug wire being an NB. The NA wire wasn't long enough and I'm not spending more than I have to on this thing.
Also note the AL hold down tabs over the plug boots. Now don't have to worry about the plug wires popping off the plugs either.
One more question for the hive. In my profession, I'm tuning suspensions for a commercial truck right now. Springs, dampers, jounce bumpers, etc. I just had a 5 day damper tuning session with Bilstein for our truck. It made me realize how much I dislike the AFCO dampers on my car. They are the old FM AFCO double adjustables, but they need to be rebuilt and they don't have a good quality feel to them. I've ridden in a car with I think XIDAs and thought they were very good compared to my car. What is a reasonable double adjustable damper for the NA platform? I'd revalve the AFCOs myself, but I don't have access to a damper dyno any more, nor the time to do a tuning session on my car myself. I'd like to find a damper with a good base valving and can be fine tuned in both compression and rebound. I see all the brands online, but not sure which would be the best starting point without spending as much on the shocks as the car is worth. And no, Maxpeeding Rods or Racelands are not on my list :P
Thanks!
If you still have the NB2 coils, I would switch back to those.
As far as shocks, I would just go with the Xida race single adjustable. They're fantastic, and I don't think you're going to find a double adjustable worth having anywhere near that price point.
In reply to Rodan :
NB2 coils don't work with the '97 ECU from everything I've read. No tach signal.
I'll look into the Xidas. Thanks.
Second the Xidas. I'm running the "full race" Xidas and they're insanely comfortable on the street.
PMRacing said:In reply to Rodan :
NB2 coils don't work with the '97 ECU from everything I've read. No tach signal.
OK, couldn't remember if they work or not... they work with the NB1, but I guess not with the NA ECU.
I think that coil information may be based on the '94 ECU, not the later ones. Mazda changed the tach setup for 1995 and the coils changed at the same time.
The AFCOs worked well for what they were meant to do, but they weren't as durable as they needed to be. It's easy to change out the problematic upper seal - you don't even need a nitrogen bottle - but there are a few other tricks to optimizing that depend on just when they were made. The Fox work much better than the AFCOs and have a less busy front end on the street than the Xidas do. This means they're a little less pointy on track, it's a matter of tuning choices.
Thanks, Keith! I'll keep the NB coils for future use. They'll require new pigtails and my solution *currently* works.
And thanks for the damper feedback! I'm going to see if anyone has a car locally I can ride in with them.
Plan C.
At Grattan for the weekend. The car ran great all day. 10 30 min sessions (5 with an instructor candidate, 5 of my own). Last session out about half way thru, with no warning, the car lost power. Long story short, coils again. Luckily, someone had spares. This time I moved them and used ziptie engineering to hold them in place. Hopefully they'll last the weekend. I think I'll order the pigtail converter for the NA to NB 2 coils. Hopefully they'll work.
And plan C, AKA the baked potato, failed after 1.5 sessions.
I think something else is going on. On the trailer for the rest of the weekend.
I did get to drive a GT4RS and a Beck 904 replica at speed today though! I'm still grinning!
OK. I'm going experimental.
I've ordered connectors from Ballenger Motorsports (https://www.bmotorsports.com/shop/product_info.php/products_id/2076, https://www.bmotorsports.com/shop/product_info.php/products_id/4160) for the 1997 harness and 2002 coils. Working at an EV company, I'll be able to make a jumper harness pretty easily. While the harness has a 4-way connector, it only has 3 wires. The '02 coils have a 3 way connector. I've found this: 
from here: https://www.mellens.net/mazda/mazda_miata_extra_manual/1996_wiring.pdf
I have the '03 coil diagram from here: 
https://www.mellens.net/mazda/mazda_miata_extra_manual/2003_wiring.pdf
Please correct me if I'm wrong
Looking at these, it seems to agree with what Keith said that the '97 coils don't have the tach signal and I should be able to use the '02 coils.
I've also ordered a 1997 crank position sensor since I am still using a '97 ECU. Question is, will that work with the 2002 crank trigger wheel?
Thanks!
Not Keith but I had to look it up on a full diagram, but yes, black/white is power, black is ground.
My curiosity was piqued because for a long time, black was power and black/yellow was ground, for most circuits.
Got my connectors from Ballenger. So my colors don't exactly match the diagrams above. And I don't have the factory harness for the coils.
'97 Harness:
Ballenger connectors on '02 Coils:
So I can see on the '97 connectors, the BRN and BRN/Y wires are the signal wires. And I am going to guess the BLK/WHT are the 12V wires since I think they go to both coils, meaning the middle wire is the ground.
Am I to assume the '02 coils are in the same order? Does anyone have the pin-out for the '02 coils in the correct order? I have the male connectors to install on the '02 coil pigtails to go to the '97 harness, but need to connect them correctly.
Thanks for any info!
In reply to PMRacing :
This is from an archived site on swapping NB2 coils to an NB1 harness, but it indicates which pins on the coil side are which wires...
This is how I connected the 2001 COP ignition to my 1999 Miata’s wiring harness.
· Coil #1 connector with blue dot that feeds plugs 1 & 4
o Brown/Yellow Trigger wire to the top spade on the 2001 coil
o Black ground wire to the middle spade on the 2001 coil
o Black/White B+ wire to the bottom spade on the 2001 coil
· Coil #2 connector that feeds plugs 2 & 3
o Brown Trigger wire to the top spade on the 2001 coil
o Black Ground wire to the middle spade on the 2001 coil
o Black/White B+ wire to the bottom spade on the 2001 coil
This is the page (IIRC this was linked earlier in the thread as well): https://web.archive.org/web/20170403002507/http://www.mostlymiata.net/1999-2001-vvt-engine-swap/vvt-engine-swap-ignition
In reply to Rodan :
Thank you! I missed that when I went digging! Very much appreciated!
Per the VVTuner page,
"DIYAutoTune’s VVTuner system is a standalone VVT (variable valve timing) controller for 2001-2005 MX-5 Miata engines.
This system also translates the NB crank and cam sensor signals from the stock trigger wheels into NA style signals, making it perfect for swapping the VVT head into earlier Miatas. Can be used with a MegaSquirt EMS (perhaps an older unit you already have that doesn’t support VVT) or on its own to get the most out of your variable valve timing."
To me it sounds like you keep the NB trigger wheel and then wire the VVTuner box to spoof the trigger signal for the NA ECU.
The connectors should be marked A on one end, maybe C on the other. Might need a magnifying glass. Pinout's in the wiring diagram you posted.
You'll need to log in to post.
