Hondata

I guess that’s another issue. I use the same battery in all of the datalogs with all the different temps.
It only starts the car above 32F and it doesn’t fluctuate the batter voltage when it’s also above 32F.
I’m just gonna continue to changed the ECT sensor when it’s below freezing temps.

It’s still not going to get addressed that the ECU fluctuates when it’s reading ECT below 32.
Literally the ECT will be 30F, won’t start, and voltage fluctuate. Then ECT will hit 32F, no problem starting, and no voltage fluctuation.
I hope someone will look at this more deeper than just saying the datalogs’ voltage fluctuates and that’s the reason.
Thanks in advance.

The sensor values are fluctuating because the ECU is continually rebooting because the battery voltage is too low. Seems like that is the root cause.

Yes, I understand, but isn’t it unusual that it only fluctuates when the ECT is below freezing?
It only does in when it’s below freezing, so can that be looked into deeper into the ECU what is causing it to do that? It just take out the reliability of the car if it keeps doing that during winter times

I’ve been having similar issues to this with my turbo d17 that I’ve built. Always been able to start above 32F but will not start below. Just keeps cranking and cranking l. Have tried adding and subtracting fuel both ways to both the cranking fuel trims and the cranking pulse width tables and have been unable to get it too start if coolant temp sensor reads below 32F. If ecu is reading below 32F and I plug my spare coolant temp sensor I’ve been warming up in my hand it will almost immediately fire over. Had to install a block heater to help in the extreme cold we have sometimes. Would really like to resolve this issue with out have to use a block heater or spare sensor to get it started in the cold temps

JAYrock wrote: Tue Mar 22, 2022 7:34 pm I’ve been having similar issues to this with my turbo d17 that I’ve built. Always been able to start above 32F but will not start below. Just keeps cranking and cranking l. Have tried adding and subtracting fuel both ways to both the cranking fuel trims and the cranking pulse width tables and have been unable to get it too start if coolant temp sensor reads below 32F. If ecu is reading below 32F and I plug my spare coolant temp sensor I’ve been warming up in my hand it will almost immediately fire over. Had to install a block heater to help in the extreme cold we have sometimes. Would really like to resolve this issue with out have to use a block heater or spare sensor to get it started in the cold temps

If you read the through the whole post, the conclusion was it glitches and fluctuates in voltage and sensors when the ECT is under 32F.
The ECU glitches and there’s nothing we can do about it.
Changing the tune does not help. No matter how many datalogs I have sent.
Carrying an extra ECT sensor is our fix unless someone in Hondata really goes deep into that glitch or corruption in the hardware.

I do not believe that it is a software problem. Likely the ECU is powering on additional sensors when the temperature is low (o2 heater etc) or just the increased injector duration at low temperatures is dropping the voltage. I'd really like to find out what happens if you have a battery that doesn't drop the voltage to 6.xV when cranking. To me that is the root cause, and the temperature threshold is something that triggers the low voltage. The ECU internal power is 5V, and it needs around 7V to operate, but ideally should be 10V or more. So when the battery voltage drops below that, even for an instant, the ECU will reboot. And then if it keeps rebooting it will never sync and start. I'd also like to see what the lambda is during a cold start. To me it looks like it is very rich, since it starts right up with a shorter injector duration. As above a long injector duration is going to drop the battery voltage and may be a problem. Remember also that there's a lot of people running the KPro on the D17 without a problem.