Warm idle is set assuming the bleed screws are closed. Cold idle may have some additional air come in via the bleed screw ports using the idle control valve, although due to the size of those ports I only get about 100 rpm extra. I will get a log soon. I need to upload some changes that should fix the lean cruising conditions, if I can get it back down to 0% trim at cruise, that may solve the off throttle stall.

If it has the same size nut as the FB/FC I'm interested.

When I ordered it, there was an underdrive option and I did not select it. They may have given me an underdrive pulley anyway, I'm not sure how to properly measure though.

They might be all underdriven. Count the number of teeth on the alternator and the number of teeth on the CS. That will give you the ratio.

If you're doing fine with charge at 1.5k and up sounds like you have an under driven alternator for your application. Might be fine for someone who can't idle that low (BP or PP) or someone who is racing all the time.

On my car the crank shaft pulley measures 4.5" and the alternator measures 2.5" (because we are dealing with a ratio I can measure from the outside and I don't have to care about where the actual belt is running.) So 1.8:1 ratio???

Forgot to check pulleys, if I have time I'll count the teeth this weekend.

I finally got an air filter on, but I had to ditch the air horns because they wouldn't fit underneath.

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This of course also messed with my entire vacuum line setup which doesn't fit underneath. I hooked up the ECU map sensor and FPR and left everything else disconnected for now (purge, idle, cruise).

I'm still having idle issues and I'm now thinking it could be fuel pressure related. The car drops into idle fine if you ease into it with mild throttle, but it won't come down off high vacuum into idle, even after I spent a ton of time messing with high vacuum fuel delivery and AFRs. I've got throttle off overun disabled, idle control disabled, pretty much anything that could mess with idle but it still drops like a rock when I push the clutch in under engine braking. That's even after I boosted idle timing and targeted 1200 for an idle. This engine, once settled, will idle solid at 800, but I just can't get it there without stalling it and popping the clutch as i come to a stop.

I'm going to disconnect the vacuum line from the FPR since I don't need it for boost reference and see what happens then. If that doesn't solve it, I may start over with a TPS tune, or just throw out the Adaptronic and go with a Haltech. Something isn't right here, it shouldn't fall flat on its face when I close the throttle.

First track day of the season is tomorrow. Since I had to bleed the brakes anyway, I figured I would rebuild the master cylinder first. Thought it would help firm up the pedal a little, it still doesn't grab on initial application, but it's definitely firmer and a little easier to lock them up. Of course it's going to rain so I'm sticking with the Vredesteins instead of mounting the Nittos.

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Tackled the rear links last night, will drive it to work today and see if it feels different. These were original and had 40k miles on them. I just went with all OEM replacements. Sway bar end links are beckarnley though. I couldn't find rubber center bushings for the sway bar so I left those for now, and will try the energy suspension poly bushing I bought later.

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I let the car idle right after a cold start for a few minutes this morning, 800-900 RPM, 60 degrees out. When I hit the road the alternator crapped out again. I'm wondering if it's...
A) low RPM underdriven
B) engine bay temps (I have seen upwards of 130 degree intake temps, but I'm not sure the sensor is calibrated properly)
C) too much current at low RPM due to ignition dwell times

Good thing I had the AC Delco RockAuto alternator handy from the last failure. I swapped it in and made some changes to the fan override circuit. The fan was set to turn on at around 190F if the fan controller circuit didn't already turn it on, but I decided to make the override switch it on low any time vehicle speed is below 10mph to mimic the mechanical fan.

I'm still having a stalling issue that only occurs when I come off high vacuum coasting. The AFRs are fine but once I push the clutch in, the RPM drops rapidly and it keeps going past idle speed and the engine acts as if it has been shut off. I thought it was maybe a vacuum leak, or something in the timing or fuel table but I have all my vacuum lines disconnected and blocked off except the MAP sensor. I even disconnected the brake booster for one drive to see if it was that. Now I'm wondering if the high vacuum is pulling shut the throttle places and choking out the engine or something. Is that possible? If I pop the clutch back in, the car runs fine and I can free rev it without stalling.

Might be time to have your complete electrical system tested as previously suggested. Seriously doubt failure of both alternators due to 130 degree underhood temp or even double that for that matter,a lot of vehicles have very hi underhood temps,especially turbo cars.
Having worked on running engines for many years in shop temps of 90+ degrees,i liken it to working in close proximity to a blast furnace.Ignition coil amp draw would not be a factor in alternator failure,again a lot of cars oe run 2x number of coils as you are without issue..
There was a question of alternator possibly being underdriven. While this is possible,it would not directly cause 2 alternator failures in such short amount of time.

I'd say the alternator is a combination of some issues.

I think the battery is dead (dead batteries are not good for alternators). I have seen a few alternators kick the bucket from bad batteries and AGM/gel batteries are the most notorious.

I do think its underdriven. Don't think that's causing the alternators to fail, but its NOT helping a poor battery.

I've seen under your hood, so I do not think corrosion or oil leakage is an issue.

I've never seen excessive draw kill an alternator, but I guess if could cause the alternator to run hotter??? 130 isn't enough to make it fry I wouldn't think, but possibly the alternator itself is the heat source and your sensor isn't close to the alternator. What does an IR thermometer say the alternator is running temp wise?

Might be drastic, but to rule out everything, why not return to stockish. Just to see if your problems go away. Lead acid battery, 70 amp second gen alternator and a regular pulley system.


On the shutoff at idle I will say that if you are using an boost referenced FPR it is NOT supposed to be plugged into a vacuum source. 100% says it in the manual if you are not boosting leave this port open. You made mention of opening this port earlier I don't know if you had already tried it.

I'd have to look up the instructions for the FPR. I was mainly using it to drop fuel pressure at idle but I can tune it without that. It's got enough injector headroom to run at a lower overall pressure.

The battery is the one variable that hasn't changed between old motor and new motor. I did deep cycle it a few times trying to get the motor fired up but it holds a charge still. I forget exact voltage, 12.25 rings a bell, I will confirm that and check voltage drops across various grounds to make sure it isn't a bad ground or something.

Update from today's track day...
Motor pulls great and had me lifting occasionally where as with the old motor I was mashing the pedal like a go kart. Made it through all three sessions then rolling into the pits on the final session the low coolant light went on. Engine temp was below half-way, where it usually sits. After some brief investigation, it looks like the seal blew out between the water pump housing and front plate. Ended up getting it towed home when it wouldn't hold any water after we refilled it.

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Late update, but it was in fact that water pump housing seal. Before you ask, yes I had the washers installed on the other studs, perhaps I over torqued the bolts, or under torqued, or coating the seal with RTV made it slip. I don't know. This time I didn't coat it.

While I was in there, I decided to try the alternative side draft intake to see if I could make a little more power. Butt dyno says it's pulling better up top but torque below 3,000 is totally gone now. I'll get some official numbers once I sort out the remaining issues. Right now there is a big discrepancy between the two O2 sensors. Unless I have things backwards I'm seeing idle AFRs of 14 for the front rotor and as low as 11 for the rear rotor. I'll check for vacuum leaks tomorrow....but other than that it has a much better idle so it could just be a bad sensor in need of recalibration.

Cold starts, and hot starts for that matter, have become an issue. Well, they were an issue before but it's worse now. It really struggles to catch and when it does finally catch requires increasing the throttle until the revs finally pick up. Not sure if starter is spinning too slow, compression issue, or cranking air/fuel issue. I had to do the ATF trick just to get it started after it sat for a few weeks.

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The motor has been running better lately thanks to numerous days driving back and forth to work and taking big data logs to fine tune the cruising fuel cells. I also worked on the transient throttle response and eliminated all hesitation.

The fuel map stuff was pretty straight forward. I've got the closed loop set to allow changes up to 10% and I just lowered various cells by 1-2% at a time until I started getting a consistent trim level across the whole table. It still changes a little based on ambient conditions, like it's been warmer lately so I'm seeing everything sit around -2% but there are no spikes in trim level anymore.

The transient throttle took some work but I was able to dial it in. First thing was to use the big logs to figure out the predictive map table. I changed the Y Axis to TPS% and copied over those values to the table. I had done this before many times and it would typically cause the transients to get worse. I would get frustrated flooding and stalling the motor and eventually just revert to the settings that were in the table before. The tuner had done the same thing and increased a bunch of values to force the ECU to dump more fuel. That worked, but it meant there were still cases where it was predicting the wrong amount of fuel squirt at high RPMs. Anyway, now with the correct "predicted" values in the table I started messing with Asynch Gain % and Persistence. I took quick logs and looked to see what was going on. The initial tip in was fine but then it would lean out...so I increased persistence. Then it would flood the motor so I decreased Asynch Gain % until it finally smoothed out. I can now mash the pedal at any RPM, yay!

The last issue I'm having is some bucking off throttle. I have a few things to try. On my way to work today I noticed the idle had gone very rich and the timing is on the high side of the idle control range. I think I need to open up the throttle plates a little more to let more air in, then bring the idle down by retarding the timing. That may help a little, we'll see.

My final map

https://cimg7.ibsrv.net/gimg/www.rx7...09337cef77.png

Transient Throttle settings

https://cimg6.ibsrv.net/gimg/www.rx7...997da0ce29.png
Average trim values for all fuel cells

https://cimg8.ibsrv.net/gimg/www.rx7...73ebf1506b.png

Average AFR for all fuel cells

https://cimg9.ibsrv.net/gimg/www.rx7...794620b68b.png

The last 12 months year in review...

I basically only drive the car at track events because I don't drive anywhere anymore. Spring of 2021 I installed a 4.77 rear end from a Kia Sportage. Took it to a track day and that change alone made a huge difference. I cannot see running a street port motor without it honestly...or any n/a 12a motor (will get to that shortly). However, the motor started consuming a ton of oil and I couldn't work out what was going on. It went from a 1/2 quart per fill up to a full quart. I don't know if it was oil control ring seals or something else but I had some fuel starvation at the track on a long sweeping left hander that leads into a very steep uphill. Felt the car hesitate a bit, thought it was gas sloshing around, but when I made it to the straight the motor just lost all power. I shut it down and towed the car home.

Summer of 2021 I pull the motor and stock transmission. I reinstalled the original motor (stock ports) along with a spare transmission that has miata gear set with shortened input shaft. I took all accessories and intake from the built motor and just slapped it on the stock port motor. Fired it up and gave it a quick retune. Took THAT to the track and it's honestly a much better experience. The motor has a nice meaty power band and for the most part keeps up with most Miatas until I hit the corners. I was in a bit of a rush when I did the swap so I didn't even carry over the lightweight flywheel and clutch. I'll worry about that later since the stock motor has now developed a small leak from the output shaft seal.

Let's see, the innovate dual wideband failed and killed two more $80 sensors. I gave up on it and installed a single AEM UEGO and it has been much more reliable. Last weekend I was at New Hampshire Motor Speedway and it was a pretty good outing until I ran out of front brakes. Before that happened though, I was able to outpace a 924S. I would have thought a stock port 12a would be no match for a 2.5L Porsche but we were the exact speed down the straight. He had more confidence with his brakes but I had better corner speeds. We both had 200tw tires. My video recording was acting up but I did get a few laps of an early session.