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Old 09-05-2016, 08:46 AM   #21
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Originally Posted by deezums View Post
Because it mucks up the entire megasquirt, it's a voltage offset issue except it's not a linear or consistent offset. It apparently interferes with the rest of the inputs, that's my only explanation for it.

Your megasquirt needs clean ground signals for all the input sensors, MAP, IAT, TPS, etc.. If these sensor grounds get tied to the engine block it will cause inconsistent readings, if your traces aren't noise free in megasquirt this would be why. All the sensors need to share a common ground as a reference point. If you ground any of them to the engine it will cause interference, basically.

For some reason Mazda decided to create a signal ground circuit for the ECU sensors, but they tied it to the head compromising the signal ground inside your megasquirt now. The wire I told you to cut is where they grounded it on the block. If you ever wanted to go back to stock, just crimp a new ring terminal on it and reattach.
I had a look for the wire. It's the one that goes to the inlet manifold. a little spade tab. Then there is also a wire on a ring terminal that goes to the head. This wire is all black where the wire on the inlet manifold is green/black.

Will cut and see what inpact it had.

Originally Posted by 18psi View Post
Thanks. Odd thing is I drove it Sunday and the fueling was spot on even though the air tempertures were the same from what I could see. (no doubt it wasn't hence fueling off)

I checked my logs for GAIR (FUEL: IAT Correction when using Rev's MS2e) and it was adjusting fueling.

As mentioned above. I'm going to rescale the X values and set the Y all to 100% do a little bit of auto tuning for the current weather conditions and with a little bit of trial and error I can adjust the correction to keep my fueling in boost as it should be.

To my mind closed loop should be doing it's thing to keep the rest of the map in check when out of boost.
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Old 09-07-2016, 06:30 AM   #22
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May have found my problem... Possible.

Main 4 pin relay died on me on the side of the road.

Reverant​ advised me on a few bits to check. So thank you to him for the last night help.

I ended up using a hairclip (ironic really)

to jam it on which funny enough... made my fueling hit 10.5 AFR on WOT. so it's possible due to a bad connection the voltage dropped which caused a few problems. as I was hitting 13.1 volts & with it jammed on it was 13.6 volts.

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Old 09-07-2016, 08:08 AM   #23
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Running the ideal gas law in a very non-ideal environment is a great way to have a multitude of tuning problems, like: cant start when its hot, or horrible idle when it's hot, or it's too rich when it's cold, on top of having a completely worthless ve fuel table.

******* listen to me when i say: zero out the MAT corrections table completely by setting it all to 100%.

Tune your fuel map without any temp corrections.

Your EGO should have enough authority to keep AFRs in check for little swings in temps. If you notice on very hot days, the car is fatter or EGO is pulling fuel then tune the MAT Corrections Table to keep EGO from having to work to keep the AFRs in check. Similarly, if you're rich on cold nights, or when winter hits, you can tune the lower end of the scale to add in some fuel

I just tuned an N/A car this weekend. Average intake temps are 160F, on the 90F day we tuned, they would hit 190F. If I used the "ideal" curve, MS would be removing 20% of fuel from the fuel map. That's insane.

I would then have to over compensate the fuel table by adding 20% to my VE Table during my tuning, and as soon as intake temps were lower, the table would be completely fubared and unusable and warm-up would be adversely rich and shooting raw gas and flames out the exhaust. So then I'd go and reduce my ASE and WUE so it wasn't so rich warming up on a cold morning -- and the next time the car got warm and i tried starting it, it would be very lean during warmup and worse as I drove... See the problem yet?

No? Okay, if I was tuning a boosted car it would be worse. Since the first days of MS2 the MAT corrections have been fucked. I tried very hard to have the MS developers change the code, but the best I could get was them to change the MAT corrections table to what it is today, instead of having to run an inverse table just to negate the built in ideal curve.

Fun Fact: Turbos create heat. Even with a really good IC, you should be seeing increased intake temps.

When you're in boost, you want to add fuel to: slow the burn, decrease cylinder temps, and increase knock threshold -- crazy concept.

The ideal gas law curve in the MAT Corrections -- as deezum posted -- ensures the MS PULLS fuel as your adding boost/heat into the intake. It only gets worse as your IC heatsoaks and AITs increase more. This is very dangerous.

That table needs an RPM decay, as well as a MAP threshold so you can basically disable it above a certain RPM and/or kPa value. There's no reason you should blindly be pulling fuel based on estimated intake temps, when you should be using closed loop fueling anyway. It's ******* dumb to try to pull fuel arbitrarily, just so EGO control puts it back in.

cliff notes: if you really hate yourself, and hate sound advice, use the ideal gas curve.

Last edited by Braineack; 09-07-2016 at 08:23 AM.
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Old 09-07-2016, 08:38 AM   #24
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Thank you for the advise.

It's a good job I had already set it to 100% across when you originally said :P

So far it's been okay. But I think I've had a underlining problem with voltage caused by the relay to throw my fueling out also.

In adition to what you have said.. It makes total sense.

Seems silly for them not to adjust it for the boosted crew.

It's almost like you need a closed loop option for boost and have a low auth. to just make them slight changes during weather changes.

Last edited by Lawone; 09-07-2016 at 09:30 AM.
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Old 09-09-2016, 02:20 PM   #25
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Done a little bit of tuning with the MAT correction.

as the temperatures have dropped here in England, Mainly at night. The below seems to be working well keeping my AFR between high 10's and low 11's during WOT.

Only spent 30mins or so. So will still need fine tuning and when it gets hotter also.

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