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Hey @Jables , just curious what cat you ended up throwing on your exhaust? I'm looking at doing the same and found a Flowmaster I'm likely going to end up grabbing but figured I'd see what you grabbed.
Hey @Jables , just curious what cat you ended up throwing on your exhaust? I'm looking at doing the same and found a Flowmaster I'm likely going to end up grabbing but figured I'd see what you grabbed.
I literally bought the cheapest 200 cell cat Amazon had to offer. It was $25. I "temporarily" installed it with stainless steel exhaust clamps (2 pack was $17). Honestly, I'll probably skip welding it in place, the clamp result is perfectly pretty if you take your time. I also don't expect this converter to last more than about 10,000 miles, so removal/install is super simple with the SS clamps. So far, boost is under control and the smell is gone during typical cruising and idle once the cat is warm. If you really give 'er the beans, the extra fuel will overwhelm the capability of a cheap converter, but not an issue for me!
Lol, I love it. I guess I might consider those clamps as well. The local muffler shop said I could bring the cat in and have it welded on for $80-100. Sounded like it would take about an hour to get the job done, so not too much of a hassle, but the clamps would be cheaper...
I'll be interested to hear how that cat holds up. I've seen all of the generic ones on Amazon and have wondered how big of a difference there is between those and the name brands. I don't have to pass emissions anymore so it's not like I'm trying to satisfy the ECU, I just want to satisfy my nose. My friend said driving behind me with his windows down seemed like a pretty good gas chamber simulator
...My friend said driving behind me with his windows down seemed like a pretty good gas chamber simulator
Hahaha I know the feeling. Idling in the garage sets the CO alarm off with the door wide open sans cat (), didn't do that with the factory setup. So far the new cat is keeping the CO in check as well. I figured I could buy 4-5 "AUTOSAVER88" cats for the same price as those magnaflow/walker/flowmaster cats. So far, I'd recommend the cheap setup with clamps to enable easy future swap outs.
Happy 2025, everyone! New year, time for some new fuel! Got a flex fuel sensor installed over the holiday break and just recently got access to E85 in South Mississippi. Found the ethanol content is around 60% right now (winter blend....I hope).
I have EBC off to compare to another dataset from the same strech of road with the same engine/temperature parameters. As you can see, same fueling, same boost level. 6 degrees of timing added through flex fuel corrections. The engine actually sounds quieter with my knock detective audio out. Loving this corn juice so far!
Very nice, and only 10 PSI! Would you mind posting your timing map? I assume you're normally running 93 octane?
Here ya go!
This table was tuned with 93 octane non-ethanol fuel. I attached my tune, which has the flex fuel modifiers I'm currently using. Haven't touched the boost control yet, I'm running wastegate spring for now in the cold air. Will probably set boost modifer to 0 anyway with my stock rods.
Anyone thinking of adding flex fuel, on NB returnless systems, the loop from the feed line to the first fuel dampener is a great spot to easily hack in a GM small sensor. Was able to pull ign 12v and sensor ground from the emissions harness. Used the EGR boost pressure signal wire to run it into the ECU. Certainly the path of least resistance.
I attached a little piece of fiberglass heat sleeve against the intake manifold to reduce heat soak on the sensor. Fuel temp in Speedy is not very accurate as it is. No way to adjust fuel temp.
Dialed in EBC for a clean ramp up to 12PSI. I don’t know why I keep chasing gains with stock internals
That was with 68% ethanol fuel. It’s been really interesting how much smoother the engine runs. The additional timing is really something.
FYI, a Flyin’ Miata turbo heat shield fits over a Kraken top mount kit for anyone interested. You just need to remove the corner notch out tab.
My battery was beginning to slow crank, and I found a NOCO NLP30 for $105. Couldn’t pass that up! The cranking speed is INCREDIBLE with a lithium battery setup.
Width and height dimensions are the same as stock. Don't mind the custom battery hold down strap, the PO destroyed the factory one. It would still work with the factory bracket just fine.
Car is still running great, but I feel that I've hit the limitations of the SpeedyEFI board. I recently upgraded to Bosch VW/Audi coils (GREAT upgrade by the way. I DIY'ed the whole thing for $120). I was trying to figure out how to wire up sequential ignition....come to find out the PNP 01-05 board that SpeedyEFI uses only has 2 ign channels . I've also had some intermittent runability issues, mainly around flex fuel, when it comes to AE, tip in and tip out. Luckily for me, someone had listed a MSPNP Pro for an 01-05 on FB marketplace. The catch was "The Alternator Control circuit doesn't work. Sent the board to DIY-EFI and they said it needed a new daughterboard." I got it for a great deal (cheaper than my Speedy was!), so I figured it was worth building a work-around to control the alternator to gain some seriously needed fueling/ign controls.
Anyway, got it bench powered so I could test run it and see what was going on with the alternator circuit before installing in the Miat. I did NOT want to risk frying anything. Unit powered up perfectly, tune file was intact (and ROUGH ), so I pulled up output test mode to run through the PWM3 circuit that controls the alternator. Everything was completely normal? Triple tested to be safe....all good.
So that rough tune I mentioned? Settings for alternator control were a MESS. First, it was turned off . Second, they had the wrong control output selected. So changed an "OFF" to "Miata 99-05" and selected PWM3 as the output. Plugged 'er in and alternator kicks out a perfect 14.4v!
TLDR; SpeedyEFI boards can't do full sequential or refined flex fuel control. Time to move on up to an MS3 Pro! I guess that's the end of this thread. I'll link the 2nd chapter in here
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. I've also had some intermittent runability issues, mainly around flex fuel, when it comes to AE, tip in and tip out. Luckily for me, someone had listed a MSPNP Pro for an 01-05 on FB marketplace. The catch was "The Alternator Control circuit doesn't work. Sent the board to DIY-EFI and they said it needed a new daughterboard." I got it for a great deal (cheaper than my Speedy was!), so I figured it was worth building a work-around to control the alternator to gain some seriously needed fueling/ign controls. 
), so I pulled up output test mode to run through the PWM3 circuit that controls the alternator. Everything was completely normal? Triple tested to be safe....all good.
. Second, they had the wrong control output selected. So changed an "OFF" to "Miata 99-05" and selected PWM3 as the output. Plugged 'er in and alternator kicks out a perfect 14.4v! 
