kek

G if you lost the bolts for the upper timing belt cover I just used some spare valve cover bolts I had laying around. They fit perfect and look good as well.

Too late! I already ordered replacement OEM upper cover bolts from Jim Ellis along with a new middle timing cover. It was like $10 for the bolts and required zero effort. :burncash:

2 things:

IATfuel correction table is stealing my fuel as my IAT rises throwing off my AFRs and making the car run leaner... WTF? I zeroed that shit out and suddenly my AFRs start hitting their targets.

CLT based timing retard is pulling my timing as the engine heats up, thus I start losing 1-2° the longer I sit. This makes my AFRs wonky and inconsistent as things heat up. This in turn causes the autotune to add or pull fuel.

OK, so fuck me right?

So on the first point, why in the world would I want it to pull fuel as the IAT rises in a boosted application? This seems suicidal unless I'm completely not understanding why it does this.

On the second point how do you get a consistent set of AFRs if the ECU is going to jack with the timing? Pulling 2° changes my AFR by a full point. How do you deal with this?

Advice on the above would be awesome, if anyone is still bothering to read this train wreck of a thread.

What is "IAT fuel correction table"? Is it "MAT Air Density Table"?
The MAT Air density table pulls fuel as air temps rise, because hotter air is less dense, and has less oxygen, thus you need less fuel.

What is CLT based timing retard? Again, I don't see this either! I do see AIT based timing retard.

Yes, MAT Air Density Table.

Well yes, hotter air is less dense thus has less oxygen and thus you need less fuel except that its making shit go lean. Fuck that table.

https://www.miataturbo.net/attachmen...ine=1435810970
There, I fixed it. I'd rather it be rich than go lean and continue to piss me off.

Yes, again sorry, MAT-Based Timing retard.

Pulling timing as shit gets hot makes some sense, but it fucks with the fuel and complicates tuning.

What else am I missing that I don't know I'm fighting?

MS in the past, the MAT air density was an equation you couldn't modify. Now it's an equation with a correction table, so you can compensate for non-ideal-gas-law behavior such as what you're seeing. Ideally you should tune that curve so AFRs stay constant with constant timing and varying air temps. Mine is non-linear too, I need to work on that.

AFR's are going to "change" with timing because when you retard the timing, the combustion efficiency drops and you end up with more O2 in the exhaust, and it reports a lean condition. This effect will be small unless you're pulling a lot of timing. 1-2 degrees of retard will change AFRs maybe 0.3-0.4 in my experience.

You really don't want to pull fuel if you're pulling timing for high AITs, obviously. Best case is fuel stays the correct duty cycle to maintain your AFRs, and when your timing retard hits, it will show a touch lean but that's nothing to worry about as it's just the timing retarding affecting it.

I've been wanting to discuss MAT based timing retard, gonna do a search and if I don't find a recent thread with good info, I'll start one and link to it here: https://www.miataturbo.net/megasquir...4/#post1245720

Edit- posted link. My MAT-based table is in the link, I think it's too conservative but it's what I'm running right now.

Depends on the code version used. Later versions it's the ideal gas law in a 2D table that you alter directly, rather than a correction curve for the ideal gas law.

When you're boosting are your IAT's significantly higher than when your idling? if so make sure the correction is only taking place at temps you never/very rarely see at idle.

I'm very surprised you see a full 1pt AFR swing from 2 deg of advance change though. That seems an awful lot.

For idle stability I've had a lot luck utilising the "Idle RPM Timing Correction" option in the idle advance settings screen. It manipulates timing to correct the idle speed based on the closed loop target.

With the PWM valve off and using the Idle RPM Timing Correction I can catch pretty hefty load changes just from manipulating the ignition timing. It's much faster to react compared to the idle valve too.

Oh, don't I know it. Looking back I believe my DIYPNP had it hard-coded. One day I drove up to San Jose in 100°+ weather and idling in traffic the IAT heatsoaked so bad the ECU just kept pulling fuel and pulling fuel until it hit 18:1 and the car started to misfire. It was not a good day.

What I'm seeing is probably a combination of the 2 corrections, pulling fuel and pulling timing at the same time.

Oh for sure, I agree 100%. That's why I zeroed out (actually 100'd it out, but you get the idea) that ideal gas law table. As to why they are both active at the same time is what's killing me.

Neat. I'll sub and follow along and ask stupid questions.

Yup, see above. I'm guessing its a combination of things.

No boost, yet. I'm getting a grip on this stuff first with the stock motor before the built motor and EFR get installed.

Yarr, see above. I've not had a chance to play with it since I noticed the corrections.

I like this, a lot. I'll have to play with it and see if its something I can figure out. Out of curiosity, what timing wheel are you using?

Thanks guys, I appreciate the comments :bigtu:

I too run the timing correction idle stuff. I think I told E02K already here, but if not, it works great.


On the mat timing correction table, I need to mess with it myself on my own vehicle, so I can't really tell you what to set it to. I tried zero'ing it out too, and it helped, but then when it got hot it ran rich or lean, I don't even remember, but it was off. I put it back to stock curve and will actually tune this down the road.

I run the OEM timing wheels, they work great.

They are both active at the same time since they do 2 different things. Ideally we will tune both, and they will work together to make everything great. When both work, a datalog should show AFRs are constant until the timing retard begins to kick in, then it will show AFRs going leaner. But not a lot, just a little.

S'all good.

I was asking richyvrlimited about the timing wheel because I'm wondering if higher resolution wheel might make it more responsive. My 949 balancer is still on the bench until I get my seals and timing set installed so this would be the time to change wheels.

Stock wheels FTW. They work fine. The only benefit to a higher-tooth wheel is off-idle timing accuracy and even then who cares whether I shoot from 20-25 or 20-23.5 in 0.003 seconds because the wheel lagged a bit?

<p>I'm on the stock wheel</p><p>&nbsp;</p><p>Reverant has used both the stock wheel and a hight tooth wheel and couln't tell any difference between the two.</p>

Cool, thanks. I probably don't need to be buying more parts anyway.

Lean tip in is AE, right? Ungh.

I'm currently set to Time-based AE. I thought MS3 was supposed to have options for EAE?

I don't run EAE, just the accel pump and that's it. Accel pump is for big transitions, EAE is for smaller ones I believe.

How lean is the tip in? What rpm/load or driving condition?

The way I do it is if goes lean a bit but doesn't affect driveability, I don't worry about it.

This works for me with 1,175cc/min injectors on my car.

https://www.miataturbo.net/attachmen...ine=1435946170

humm...

https://www.miataturbo.net/attachmen...1&d=1435946457

Haha well I think you found your problem!

<p>What pat said. EAE is for slower changes. AE is for quick ones.</p>

Well, this is frustrating and I'm stumped. I hate wasting his time but I guess I'll email Rev and see if he can advise. I feel like 90% of the time when I run into an issue like this its something stupid, like a check box I missed on some sub-menu buried somewhere. :facepalm:

kek

https://www.miataturbo.net/attachmen...1&d=1436025807

Now I'm wondering why it was off in the first place.