@elfini~fc3s, thanks for the feedback on the injectors. I agree that it's unlikely the injectors are causing the whole problem but now I'm appreciating that they're not helping.

I don't want to distract us from discussing the core issue of reviewing my tune, but is there a consensus on which injectors would be my best choice? It appears all the companies are using the same basic injector that they modify a bit. Flow Force seems least expensive, Deatchworks is in the middle, and Injector Dynamics is the most expensive. Is there a reason I wouldn't go for the least expensive since they're basically the same?

Flowforce doesn't modify them at all, which is why they are the least expensive. All Nigel does is buy in bulk to reduce cost, then flow-test, dynamically match, and include everything needed to drop them in. He's local, so we helped with some fitment foibles that have always plagued the ID1000s, so the FF610s now fit better than those.

For stock bottom end or light builds (sub-325whp), the FF610s give up nothing.

Flow Force 610cc EV14 Injectors

Thanks for the feedback. I'm still running my stock engine and the 250 hp it's generating honestly feels like more than I want. I might dial it back. So the 610s look like they'd work fine and are about 10% less expensive than the Deatchworks. Always nice.

In the meantime, I'm looking forward to getting feedback on the log I posted yesterday afternoon.

Ace, can you go for a 30+ minute drive and post the log of that? I am messing around with scatter plots to maybe diagnose the problem but I need more data points.

It does look like your AFR target never goes above 14.7 in cruise. Plus, your AFRs aren't hitting 14.7 reliably in cruise. Do you have EFR/EGO control turned on?

Oh, so you need a longer drive so there's more data? Sure, I can do that.

I wouldn't expect the AFRs to go much over 14.7 since those AFR targets are set to not go much leaner than that. I've attached that table so you can take a look.

If I understand your question properly, I believe I've got EFR/EGO turned on. The Megasquirt is running in closed loop mode and is making adjustments based on inputs from the O2 sensor. But I don't want to assume we're talking about the same setting. Can you point me to where I'd check in TunerStudio to make sure?

Below is part of my AFR table. I have mine a bit tailored due to my wideband reading a bit off, but should give you an idea of what I aim for when cruising.
https://www.miataturbo.net/attachmen...ine=1450895592

I am at work and can't look at tunerstudio but I believe it's:

Fuel>AFR/EGO Control>

I am by far not the best tuner here so I will be happy to hear other opinions, but it seems like to me that your AFRs are jumping around a lot in cruise if I remember your log correctly.

Also, your AFRs in cruise don't have to be 14.7:1. My map is closer to Shuiend's.

@shuiend, OK, I see you've leaned out the AFR targets in that midrange zone. The table I'm working from is the base configuration Rev placed on the ECU and I don't *think* my tuner changed any of that. But if you're not getting any knock then I figure your AFRs would be OK and would result in less consumption. Out of curiosity, why do you suddenly go rich at the higher RPMs?

@chiburbian, I'm attaching a screenshot of the AFR/EGO screen. It looks correct based on my knowledge.

I'm going to go for a 30+ minute drive as requested. If you tell me stuff looks generally OK in the log then maybe we can play with the AFR targets, autotune a bit, and then see where we are.

If your tuner actually tuned cruise and stuff by hand then autotune will screw that all up. If he didn't even change the basemap and then autotune I would find a new tuner

He definitely tuned by hand on a dyno and I didn't figure that any autotuning I did would be a final configuration. I wanted to see what kind of effect it had on fuel consumption and then revert it when I take the car back to him. But maybe it's better to share what we learn here and leave the changes to him.

And honestly, I can't remember what the base AFR table looked like from Rev so I don't know what changes might have been made.

I logged a good long ride on my favorite mountain roads and then did some stop-and-go driving for good measure. Please let me know if this will work for you.

I wanted to bounce something else off you too. We've been talking about leaning out the mixture in the non-boosted part of the fuel table, but I'm thinking back to the AFR targets with my Link. I've attached that table from Flyin Miata for reference. The Link was generally running at 14.8 - 14.0, which is about what the Megasquirt is running, and had lower fuel consumption than the Megasquirt.

So on the one hand, it seems reasonable to lean out the non-boosted mixture if that's what's needed, but I'm struggling to reconcile that against my experience with the Link. All things being about equal, the Megasquirt seems like it should be returning at least as good fuel economy as the Link at the same A/F mixture.

What do you all think?

Is your AFR gauge matching your indicated AFRs in tunerstudio? (in other words, is it calibrated on the megasquirt?)

It's hard to tell if they're saying *precisely* the same thing on the gauge and in TunerStudio because the numbers move so quickly. But in general, yes, it looks like the numbers match.

You can setup in TS in the VE Analyzer live section to only autotune certain sections of your VE table. You could set min and max rpm then use the custom filter to only do between certain KPA's I believe. Get that setup, lean out the center section of your AFR table like I have mine, then go drive on the interstate at constant speeds between 60-90mph. Also you don't need to worry about that lean and knock. I have ran as lean as 18:1 with no knocking in that area, I don't suggest it, but it is doable. If you want to dig deeper you can search some of Hustler's old posts about his super mileage white DD where he was working on tuning for MPG.

@shuiend, you said that your AFR targets are tweaked because your O2 sensor is a bit off. Would you suggest that I use the 15.4 that you're running or should I try something else?

Hi, folks. I took advantage of my day off to do a bit of experimentation based on your feedback. I tweaked the AFR target table a little differently than shuiend suggested, but I believe I got the general idea deciding to make it a little more conservative (rich) in the higher RPMs. I figure I can lean things out even more if things look like they're going well.

I then autotuned everything in the non-boosted part of the table, i.e fuel load <100 kpa. The car seemed to run just as well at 15.4 as at the 14.7 I was running before. Would you please take a look at that updated table and let me know what you think?

I also took a bit of a datalog and would appreciate your feedback on that.

Finally, I checked if the O2 gauge reads the same as in TunerStudio as chiburbian suggested. It turns out that the gauge is reading about .3 lower than TS. So if the gauge is at 14.7 then the software is showing 15.0. It seems like that could account for excessive fuel consumption since the car would be running richer than the MS thinks.

I went into Tools/Calibrate AFR Table, selected the Innovate LC-1/LC-2, and wrote it to the ECU just to be sure. I didn't see anything change in TunerStudio though. Do you have a suggestion for how to make them read the same?

Agreed.


OP, I looked at the first log you posted. At 1772 seconds into it, it shows 4,000 RPMS, 4.5 PSI boost, 12.4 AFRs, and 37 degrees of ignition advance.

Just so you know, that's wayyyyyyyyyyyyyyyyyyyyyyy too much timing, and your detonating. RPMs drop while in boost, which could be a misfire but likely it's from detonation.

At 1919 seconds on the log, you hit max boost. SEVERE detonation is shown, to the point that RPMs were dropping when you gave it gas. At this point you were running 8 PSI boost, 12.0 AFRs, and 36 degrees of timing!!!!!!!!!!

Start over on your spark table, and do a compression test and pray you haven't nuked a piston. And new plugs. And whoever did you spark table, don't ever let them touch your car again.

Oh, wow. Thanks for the feedback. That's sure not what I wanted to hear since I had the ECU professionally tuned to avoid this kind of trouble.

I'm confused about what you're saying because I'm not hearing any detonation at all and the car feels really strong. Also, when I look at that log, I see RPMs and boost gaining until I let off the throttle. Soon afterwards I see the boost drop first, followed quickly by RPMs. I also figure that an AFR of 12.0 is about right as well. Isn't that what I should expect?

Based on your suggestion, I'd expect to see RPMs drop before boost. No?

I know the tuner messed around with timing so that the numbers in the table are offset by an equal number of degrees in the base timing. So basically, he set the base timing offset from TDC where you'd otherwise expect and then added that offset to the timing table. Based on my own experiments, I believe his offset is about 10*. I don't fully understand his logic, but perhaps that accounts for the weird timing number?

Oh, I see. You're talking about the bit that starts at 1919 seconds and goes to 1921. I thought you were talking about the curves that finished at 1919 seconds.

Even so, it appears to me that during those 3 seconds, I hit the gas, the boost went up, and then RPMs went up with a little lag. I'm still not seeing where RPMs were dropping where I was giving the car some gas so I'm not able to see where the detonation would be.

That's a shitload of timing still. Basemap is like 16 degrees there