Hi all! I've been lurking for awhile but finally megasquirted my nb1 on the path to a turbo. I think that I have the tune pretty well worked by trawling the threads and google, but now that I have my VE table pretty good and I am introducing EGO I have noticed an issue. For more context on the problem, I have my wideband on a separate toggle switch in the car so that it can start and idle for a few seconds before the sensor preheats to hopefully prolong the life of my sensor. The issue is that even though I have the AFR upper and lower limits set so that EGO doesn't do anything above 20 AFR or below 9 AFR, it is working regardless. The effect of this is that when I turn my car on initially, the computer isn't receiving a wideband voltage so it reads 7.4 AFR, but the EGO tries the lean the car out as much as it can regardless. I am attaching my tune, as well as a datalog file, and a graph of the data log showing what happens when I turn my gauge off and back on. Oh, also its not just when the gauge is off, it appears that EGO is also trying to richen the mixture (unsuccessfully, I just see EGO correction % trying) when overrun fuel cut is active... WTH? Thanks for any expertise you guys might have.

-Riley

Edit: Just realized I should clear this up, the reason the idle is high is that I was sitting in the car and had the AC on cause it was hot. It does this regardless of AC state.

Edit 2: Trying to cover my bases as I remember things. I know I can just set min RPM for EGO but I like to have it correct when idling for different conditions.

 

More than likely it’s a bug in the firmware, either native or unique to your (possibly corrupted) ECU. Reload/update the firmware and take some more logs.

 

Hmm.. I wonder if the tune could have been corrupted. Early on I was transferring the tune back and forth to my desktop to mess with settings, and my desktop couldn’t plug into the ecu for obvious reasons so I was editing settings with a different firmware version than the ecu was on. I’ll try rebuilding my tune from the basemap and see if that helps when i get a chance. I’ll try reloading the firmware like you said first though.

 

Wait, isn't that pretty much the opposite of what you'd want ? I thought a not connected/preheated sensor being exposed to exhaust gas temperatures is exactly what kills them ?

 

No,
it's heating and sitting there without starting the car. I'm on my third sensor and that one's holding up, because I have a switch in there and let it idle for 20sec before turning it on.
The MTX-L is known for very aggressive sensor heating, other widebands are easier on the sensors

 

Ive read that it’s the combination of fully preheating your sensor, THEN starting the car which blows an initial blast of cool air over the 1200* sensor flash cooling it. But I agree with you on how to avoid it.

 

I updated the firmware to 1.6. Problem maybe fixed? now when AFR goes out of the EGO defined range the EGO locks to whatever it was at right before AFR went out of range (sorry don't have the data log). I would have thought that EGO would return to 100%, defaulting to the VE map? Maybe it is and the display just freezes on its last value. Weirdly enough, I tried turning the gauge off and back on 4 times and on the 3rd time it did the same thing as it was doing before swinging to the EGO limit of 10% lean which I'm currently calling a fluke. My MS3Pro is brand new from DIYAutoTune and I've had zero other problems with it so this is really screaming software bug to me. Can any of you who have a switch on your AFR gauge try this same thing and watch what EGO does?

 

IIRC that is a known bug in the latest firmware, I don't remember if there's a work around or not. Not ideal at all, but if you back date to a slightly older firmware between what you were running and 1.6, it might fix your original problem without introducing more.