Long term trim experiences? MS3
 

Has any of you guys experiences withe the Long term trim stuff in the newer MS3 firmwares?

I would like to see if or how this works for you.

I read about it and they say to get the fuel table dialed in well before turning it on. Thus I have not enabled it yet. But it looks pretty sweet, and I will use it once my fuel is spot on.

<p>It should act like VE analyze autotune always running in the background and adjusting your long&nbsp;term fuel trims based on your short terms. Every modern OEM ECU has this feature and it's nice to see it being added to the MS3. No direct experience yet but I'll be sure to enable this and see how it works out.&nbsp;</p>

I'm planning on messing with it, whoever beats me to it post up, I too find it interesting

Does LTT adjust the entire fuel table, or a single number?

RTFM

:idea:

Will have to give it a try if I ever upgrade the firmware...

I'm not sure I see the point. I fairly regularly tweak my VE table , (say once every 2-3 months), anyway due to changing other components, or generally trying to improve the tune. LTT is to take into account sensor drift/clogged up injectors etc which takes quite a while - years I suspect.

I read the manual through once, but it was hard for me to interpret what was automatic and what took intervention to make the adjustments active.

What I am doing now is trying to tune for perfection with winter gas, and let things go rich in the summer.

For me, the LTT would take the place of that, and seasonally adjust.

Of course, EGO adjusts now. My thought is that if the O2 sensor goes out, I'd rather error rich than lean if everything defaults to the table values.

That being said, I do not have limp set up and am not sure what the MS3 would do if the O2 sensor did go bad. I think it already ignores a non-input and defaults to 100% EGO, as it should.

Neither EGO or LTT will work properly if the O2 sensor drifts and gives a value, but a wrong one.

I think only rev's CAN units make it default to something like 14.7, having the wb wired directly it will cause the car to do all sorts of weird things if it goes out, unfortunately.

But yeah, I basically have it exactly like that right now, needs about 10% to be able to compensate between 60* and 120*

No, MS3 has sensor error checking as a standard feature. EGO sensor failure detection will cause the MS3 to disable EGO and flash CEL code 7.

Oh really? well that's cool

See, there's the problem. The AEM for example has a lower limit of 10.0. This means that if you unplug it (power off, burnt fuse, analog out disconnected), the MS2/MS3 will hapilly report an AFR of 10.

If you enter 10 as the trigger value, then any time that you hit 10 (not difficult on a boosted car with a less than perfect tune), the MS3 will light the CEL. Not ideal.

WBO2's don't do a slow drift error in output like NBO2s sometimes do?

Actually, a CEL is not so bad if, as you say, the tune was "less than perfect" as a root cause.

Then, your recommendation, or preferred implementation is? LC-2 and a limit of < 10?

I think a CEL and a limp mode to ignore O2 information is better than a false 14.7 that EGO will then try to enrichen. Well, except my EGO limits in boost are pretty narrow. Still at 14.7, I will get fuel cut due to AFR protection. OK, that's not so bad. Puts me into a default Limp mode.

All these possible settings and interrelationships.

I'll have to look at how I have mine set. I am using some of the error checking features, but not all.

the CEL stuff you can put a deviation amount in too, a permanent flatline of 10:1 with no deviation you're pretty likely to have an issue of some sort.

That said the documentation yet again sucks. The deviation numbers have no explanation of what they relate to.

That's true, but not the whole story. The ECU is looking for a minimum value and lack of fluctuation. If these events are met, the ECU determines faulty sensor and disables EGO correction.

If Sensor Validation is not enabled, you are correct -- the ECU would read 0V and attribute that to the 0 volt AFR value. Best way to combat that is limit your EGO authority to a reasonable value. No different than an OE car.

Something else that you can do. Program your wideband analog output to 0:5V :: 1.5 lambda:.5 lambda. This is the inverse of Innovate's default curve. Then if you had a sensor failure, the EGO would react to a lean condition, no different than what happens with an OE ECU and the narrowband goes out. EGO authority should be limited to a reasonable amount, no matter the curve or sensor type.

Last time I checked, the AEM and the Zeitronix can't be adjusted, and the Innovate can't inverse the curve's direction. You can change the slope, but can't go from rising to falling.

I will check on the Innovate. That would be lame if so.

Ben / Rev: Can you discuss the effects / choices of combining the serial CAN box and sensor error detection?

In other words, if using the CAN input, if the sensor goes bad, does it indeed send 14.7 (Lambda = 1) to the MS3, and therefore sensor error will not be triggered?