ECU Resetting itself

I doubt many have had this issue or, if they have, are unaware of it but I won't know if I don't ask!

I've had an intermittent issue w/ my truck for several months. I call it an "issue" because it's abnormal though it hasn't adversely impacted performance and the truck has always started but it's odd.

What happens: The ECU / DTCs clear unexpectedly from time to time. Similar to the behavior you would get when disconnecting a battery or clearing DTCs. The best way you know this is happening is that when firing up the truck, there is a split second delay where it sounds like the ECU is getting an initial airflow reading before it sparks the ignition for the first time.

I then plug in my Carista and OBD Fusion app and can see the clear signature of an ECU reset (miles since DTCs cleared are 0, warm-ups since cleared are at 0-1, etc.,) and the truck restarts its learning behaviors for ignition timing, fueling, etc.,

Things I've tried: Replaced my stock battery with a Northstar and it's strong as it gets so it's not that. Make sure there are no power draws when I have the truck shut off or when starting up. At one point I thought that perhaps b/c I leave the Carista plugged in that could be the cause but it isn't since I had this happen yesterday.

One other note is that it generally seems to happen when I have been driving the truck (warm engine) then let it sit for a short period (less than 90 mins) and fire it back up. Doesn't seem to happen on a cold start.

While not a "big" issue now it is concerning if it could be an electrical gremlin or ECU issue that could bite me down the line. I do know the ECU is intended to hold it's memory and not reset (dealerships go to great length to ensure power isn't interrupted to the ECU when doing service) so the behavior is not normal.

Anyone had this happen?

 

are you noticing this only when you have a dtc?

 

I don't have any DTC. Have never had any codes on the truck... I just use that as a reference b/c when you read the stats on the ECU that's the most apparent way to tell when things have been "cleared" is "miles since DTCs cleared"

 

weird. i have bluedriver obdII reader. i should scan mine and see if it shows anything similar. is your only symptom the initial start delay? how are you determining the relearn? asking so i can be aware of any similar symptoms.

 

You can tell the ignition is a bit jumpier and shifting isn't quite as smooth for a bit but not a ton noticeable other than that in terms of driving, but in the OBD data I can see that learned values for high/low/mid throttle, ignition, etc., get reset to zero so it's having to relearn all that stuff when it resets. It's definitely clearing it's memory - just not sure why. probably electrical but would be interested to see if anyone else sees similar behavior.

 

Warranty, take it in and see if the Dealer can chase it down

 

Yeah, not something urgent but something I'll have them look into on my next visit if I haven't gotten to the bottom of it. I will be shocked if they can determine the root cause given how odd it is and how I can't prove it's actually causing "issues" but will be a topic on the visit nonetheless.

Man, my truck has such a wrap sheet! CKP, rear diff, fuel pump, warped rear drums, low ATF from factory, dry u-joints, uneven bed mount

and yet. I still love the truck so that says something I guess.

 

I have exactly the same setup as you, and while this is not happening on my truck (to my knowledge), I will check it out later today.

I also leave the Carista BT dongle plugged in 24/7.

 

Are you able to check your emissions completions through your setup? If so, see if they are complete. If not then, that would be a sign that the ECU is resetting.

I run Torque Pro.

 

They were incomplete the first startup after this happened, but after 2 more warm ups they are cleared since it's had time to run the emissions checks now.

 

Have you tried flashing back to stock?

 

Yes, I have but not for long enough. It did happen a couple of times BEFORE I was tuned though to be clear. I'm not running stock for thousands of miles to see if this happens again tuned or not and it's quite intermittent

 

You know you want to... Do it. Do it.

 

NO. Just no.

Ask @dingel5 what he thinks of that idea

 

This is interesting. I feel like mine does this as well, but it's been so hit and miss I can confidently say it's the same thing. Every so often it'll seem like the truck takes a couple extra revolutions before starting. It's so sporadic that I'm never expecting it and can't tell if it's in my head or not lol.

 

I have had a few Chrysler ecm’s do this. The ecm would loose power and clear all stored test data. I had one Jeep that would stall, automatic tranny, cycle key and fire right back up.

The only solution for both of these were new ecm’s. Good luck.

 

And now when mine occasionally sputters when I start it in the morning I will be checking the stored data.

 

What was your build date? Also, you live in an area with mice? A poke under the hood for mice damage might be worthwhile

 

Aug 2016 Baja build

Yes definitely in an area w/ mice but I have 2 cats and the truck is garage kept and I've looked for any signs of chewing to no avail. Cats kill the mice in the garage and bring them in the house as trophies.... ha

 

I'm curious what it is. Keep us informed!