My gain was 15whp on e85 compared to 91. That was pre ported tb/intake manifold so I don't know if those added anything.

I have been running the standard gm fpr/filter w/ a dw300 for a couple years with zero issues, so I doubt this was your problem, but it may work.

Edit: I believe you can see pre hpfp and post hpfp pressure in hptuners (but it's been a while since I've been in there)

Good luck!!

HPT shows a pre pressure, but it never changes or oscillates and that makes me think it is a bogus number that isn't actually being pulled from somewhere. Is there an actual sensor on the car to read the low pressure line's psi? Probably chasing my tail with the regulator and filter, but wanted to upgrade anyways. I'm out of ideas after this on the misfires. Probably just have to wait for Griff's stand alone.

Not sure on the pre as the sensor would have to be right at the pump since there is nothing but an lines between that and my dw300, but I know it does show hp fuel rail pressure for sure.

It's a bummer you are having these issues as the gm ecu seems like it's pretty solid.

It shows the actual HPFP pressure from the rail sensor, but the LPFP is an ECU calculated value that is NOT correct. Best to just get a sending unit or analog gauge and put it inline just before it goes into the fuel rail at the engine. Like LukeG said, I don't have much confidence that this will cure the misfires, but it is nice to be able to set your LP side right where you want it and having a good 5 micron filter is just cheap insurance if you ask me.

Thought I would comment - have an inline -8 10micron AN filter on my dads build, and I've been fighting the "hard start/low battery voltage" issue - last time it needed 2 battery packs to start. Finally decided to instrument everything (benchtop power supply, separate electrical systems starter vs ECU, oscope to watch everything) and it wouldn't start on freshly rectified and smoothed 15v. Threw in spare ECU, no joy.

Turns out, 10 micron filter was clogged. Argh. And yeah, I also believe the low pressure is simulated value after that debacle. Though I also had 1600psi in the rail and it still acted like the injectors weren't firing. Weird.

Working on the fuel system and realized that my return dump in the tank is too high and needs to be dropped down to prevent foaming. Will be welding on a small stainless tube to the miata fpr location. Fuelab 535 fuel pressure regulator and Fuelab 6 micron fiberglass filter are on the way from Summit. I'm running a holley hydramat for the pickup and it acts as a 15 micron pre-filter, so should be golden on the filtering side.

https://cimg9.ibsrv.net/gimg/www.mia...0d8fd411ad.jpg
https://cimg0.ibsrv.net/gimg/www.mia...1d9f0cb47d.jpg

Loaded up on E85 this morning and got to around 45% ethanol with 93 octane mixed in. Holy shit... the car can now spin the RC1's in fourth gear. Hopefully I can hit the dyno in the next couple weeks. I'm super curious where the car is at now in power. All the issues I was having are gone with E85 in the car. Misfires on cylinders 2+5 totally disappeared. I don't fully understand why, but I'm very happy. New fuelab fuel filter and FPR are on the car. Also welded up a stainless tube to extend the return drop all the way into the bottom of the tank. Came across a video that shows how bad fuel foams when you return drop isn't low enough and I am pretty sure I was driving with a tank full of foam. Got the pressure set at 62psi. Going to be picking up some of the new Nankang AR1's in the 275 flavor in the next couple weeks. Oh, and I am running a DW300 fuel pump with a Radium adapter for the Holley Hydramat for reference. I had completely forgotten what pump I had.

https://cimg1.ibsrv.net/gimg/www.mia...1cafd17dbd.jpg
https://cimg2.ibsrv.net/gimg/www.mia...4aa8fcffd0.jpg
https://cimg4.ibsrv.net/gimg/www.mia...d009fa7bf5.jpg
https://cimg6.ibsrv.net/gimg/www.mia...1052695f4d.jpg
https://cimg8.ibsrv.net/gimg/www.mia...bd828601df.jpg

Noticed that the connector on my throttle body had a broken locking clip. Searching around it seems pretty common to have issues with these connectors. Ordered a couple since they are cheap and I want a spare.

Part # 1-1438153-3
https://www.mouser.com/ProductDetail/571-1-1438153-3

Looks like all of that work is paying off...big time. Eventually I see myself going down this same path.

Not sure the power level I am at right now, but guessing a healthy 300+whp. That is the perfect level for the exocet. I have toyed with the idea of going forced induction, but I don't think that makes sense for the exocet. The LFX on E85 is more than enough to do some absolutely retarded things and the torque down low vs bp turbo is insane. I know V8R doesn't recommend anything higher than a 3.23 for gears, but I am in love with my 3.91 OS Giken setup. Roll-ons in any gear will make you giggle. And so far the miata diff with a kmiata brace plate has held up to everything I have thrown at it.

Car is now perfect except for one issue that has been pretty elusive. Randomly every now and then the car will go into limp mode when going from a stop. It's still doing this after replacing the accelerator pedal and going through every detail in the tune to see if that was causing it. The throttle body is brand new so I am fairly certain that isn't it either. The code it throws is P2138. Unfortunately this is a pretty vague code and I have seen hundreds of posts on forums about this code and what potentially caused it. The actual code is defined as an issue with the throttle connector/wires or accelerator pedal sensor in many cases. I have inspected all of the wiring and everything looks fine. Trying to find more info on this I came across an old post by Ryan Passey on another forum... https://forum.miata.net/vb/showthrea...610911&page=10

"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"

I also saw a single post on the Camaro5 forum about someone having the exact same issue and they took it into the dealer. They claim the dealer replaced the throttle position sensor wire bundle with shielded wire and it fixed the issue. Fingers crossed!!!

So I am now ordering all new pins for the throttle body connector and the pedal connector to run some prowire shielded 6-conductor wire on both sides.
https://prowireusa.com//p-2112-20-aw...ded-cable.aspx

I have heard I'm not the only one with this issue and it has been a total pain in the ass to try and figure out what it is. Never would have guessed invisible electric pixies infiltrating my wiring, but at this point I'm down to try anything to fix it.
Will update in the next week if the shielded wiring fixed the issue.

Can't believe you are spinning in 4th! Wow. Very cool, I hope the 275's help get the power down for you.

I hope the new wiring fixes your issue with the limp mode. You are so close to everything well sorted! I'm about to start wring things so will definitely be paying attention to what you find out here. Good Luck!

Thanks man! So close, only one issue left to resolve! Took the car on an hour long drive on Monday. Absolutely blown away at how well it drives, corners, accelerates, etc. The LFX engine is an amazing platform and on E85 that motor comes alive. All the work I put into this car was 100% worth it, and for the price I don't think there is anything that will come close in fun factor.

Started going through the accelerator pedal wiring last night and I can get a clean shielded run all the way to the ecu with no breaks if I bypass the Delphi lever connector. Ordered plugs for the lever connector to replace the soon to be missing wires.

https://cimg2.ibsrv.net/gimg/www.mia...4f9e23a2f0.jpg

https://cimg1.ibsrv.net/gimg/www.mia...2d42df4d17.jpg

Pedal connector now has shielded wires and made everything nice and tidy. Just waiting on the pins to wire it directly to the ecu. For reference, all six of the accelerator pedal sensor wires connect through the blue connector on the ECU.

https://cimg4.ibsrv.net/gimg/www.mia...8ea86fd7bb.jpg
https://cimg5.ibsrv.net/gimg/www.mia...d12c2296e4.jpg

Few updates...
- Nankang 275/35/15 AR1's will be here Thursday and are getting mounted as soon as they show up
- Shielded accelerator pedal wiring is done and the ecu connector pins are a pain in the ass
***Lastly and most important, if you have an LFX swap check your accelerator pedal connector. I was trying to seat the connector all the way and realized it wasn't going down far enough to lock into place. A slight tug on mine and it would come loose. I even pulled the pedal off the car to try and seat the connector with no luck. Pretty sure my connector has never been fully seated and may have been the cause of this craziness. Not sure if this is normal, but I had to file about 2mm off the top lip of the connector frame on the pedal so that the connector would fully seat and lock into place.

245/40/15 Maxxis RC1 next to Nankang 275/35/15 AR1


https://cimg0.ibsrv.net/gimg/www.mia...f1029ddcc0.jpg
https://cimg1.ibsrv.net/gimg/www.mia...54feb7a8c7.jpg
https://cimg2.ibsrv.net/gimg/www.mia...2a29de9f3b.jpg
https://cimg3.ibsrv.net/gimg/www.mia...b01db97461.jpg

I was gonna ask if it looked shorter, definitely does, looks like it's 1/4"-1/2" smaller diameter?

It was hard to shoot it at the right angle to show it properly, but I'd guess about 1/2" smaller diameter. Not sure if that changes when they are inflated???

Too bad there is no source for 15" wheels 12" wide now that we have cheap, good tires for them......