Low battery starting issues with missing tooth.

[Spudmn]

Below is a PM I sent to Fred


Hi Fred.

I am have trouble starting my engine. The real problem is that I am using a really flat battery and I am not getting sync, I guess because of the low RPM and my funny trigger wheel is not generating pulses.

The car will start fine using the distributor.

Any way I don't want to waste your time trying to sort out my problem with software when I should be buying a better battery and making a new trigger wheel.

If it is of any help I have logs.

File an issue! No, I'm serious. Dan (slater) has issues with flat batteries and sync too. If you could log the input with your open bench while having this trouble as well as a matching (from same session) binary datalog that might be helpful. We need to be able to start these things when they have flat batteries too. It's possible that the angle sucks and the pulses all look the same because of where it falls on compression/power stroke, but if it's possible to look at the LA trace or a histogram of the data from it, and recognise the missing tooth with your eyes, then we should be able to do it in software too. The default setup might just be too fussy for cranking. That's the case for other decoders too, with respect to time tolerance. Check that in the log, if the reason for sync loss is stated as time tolerance, then you can fix it with a setting (maybe) if not, as your last log wasn't, then we need to look at the logic/math for missing detection a bit closer.

Lastly, I'd encourage you to post your PM to me and my reply, in full, or trimmed suitably (only if you want to), to a thread on "low battery starting issues with missing tooth" or similar and pm em_knaps about the thread's existence. I've been making a lot of noise about this recently, and it should serve as an example to those people violating the site rules (2 and 4). And yes, you can included this block, if you choose to post this message up at all. It's no secret that I strongly prefer open discussions on development and am not shy about having my work criticised and bugs filed. On the contrary, in fact, I welcome it!

I hope this helps, and hopefully, if you post it all up, it can help others too!

Your point about the PM is noted. I had every intention of make this a forum post if you wanted to look into my problem.

The lesson for today is that you should post every thing on the forum even if you think it's a dumb question.

I hope to have the Logs and LA done soon.

[Fred]

Thanks for posting that up, I appreciate it! :-)

Did you check the sync loss reason values? I'm curious. If it's 1,2,3 or 4, then there is a setting that we need to change before spending time on the missing tooth code. Your previous log wasn't like that, though, it was a legit issue with the decoder and/or angle of wheel on the engine.

It'll be good to get some solid LA data from it. I wonder, being an open format, if we can script generation of data for a histogram from it. I really should implement the log type to just do that natively, though... sorry for the inconvenience. If you feel like going and visiting em_knaps with your LA, it'd be interesting to get a log of his with a flat battery too. It's not run in weeks, so you'd likely be in luck LOL.

Re everything on the forum, it's pretty much true. Only confidential stuff should get PMed. There should be virtually none of that here, though. I seriously considered disabling the PM system completely when Jared last ran a muck, but decided that it was too much of an inconvenience to legitimate users. I really need to do a thread on contact paths and reasons and developer time, too. Last night I was poking around another forum and found this in a sig: "Please don't send me questions via PM - use the forums instead. Thanks!" and I thought to myself "he's very polite!" :-)

Just to be clear, this has been an ongoing problem since the start. You're not a problem at all, really, but others doing the same thing typically with "where are the schematics" and "I want to run my car" and "where can I download xyz" etc really are annoying...

Fred.

[Spudmn]

Here are the logs. The LA shows that the pulses are being generated. The log shows that the sync fails because of the following codes.

66 TooWideNarrow
132 VRWiringBackwardNarrowBackwardMatchedPair
65 NarrowTooWide
84 NearlySyncedBackwardNarrowMatchedPair
117 ExcessAccelerationWideNarrowBackwardNarrow
101 NearlySyncedNarrowWideBackwardNarrow

The BRV drops very low during cranking but the micro still looks like it is running.

I won't be able to get around to  em_knaps  any time soon. I have too much on at the moment.

[Fred]

Thanks, I'll check these out later after I do the long overdue RavAGE review. The LA one will be interesting, that's for sure.

[em_knaps]

Reading reading reading.....

I think its time I did some doing doing doing...

knowing some one else is experiencing the same issue as myself
gives me some motivation to do something useful to help remedy it.

I had though it was a HW issue, perhaps with my VR circuit but having not logged it I cant say.
ill put aside a day this week for a new firmware build and setting up my laptop to do the logging.

hmmm..... food for thought.
although I have been stuffing my face lately in that respect...
watched some big bang stuff last night, theory's that the universe is bouncing, not up and down but in and out. collapsing upon itself and then once it gets to a density it cannot sustain, exploding and expanding.... of course this takes a little while...
make my existence feel so very insignificant.... almost to the extent that i feel ill.... no wonder religion is so popular... its just so easy.

[Fred]

LOL, wildly off topic, but in an amusing way!

I look forward to a log from the slater :-) with wideband, properly configured, for bonus points :-)

[Spudmn]

I am having a look at the code and this might be my problem.

Code: Select all

unsigned long tolerance = (smaller * TOLERANCE_LEVEL) / 4096; // TODO un hard code this. currently 25% tolerance
// div by 4k = fairly high minimum RPM for low teeth wheels

It kind of fits as I have low RPM and my teeth are 8-1

[Fred]

Try changing it! Thanks for the heads up on that, too, I'd forgotten. Throw a comment on issue 180 to remind me, please :-)

Check out the spreadsheet in the firmware docs dir for info on how to change it.

[Spudmn]

It looks like my problem is that the my tolerance is too tight.

I made a unit test of the PrimaryRPMISR and run the tick counts I calculated from my LA logs. This let me single step through the code and I could work out what was going on.

Just by looking at the LA logs you can see that my teeth spacing varies a lot through a revolution. This is probably due to my starter motor having trouble keeping a constant speed when cranking with a flat battery.

I have a new tolerance value that I will try tonight.

[Spudmn]

Try changing it! Thanks for the heads up on that, too, I'd forgotten. Throw a comment on issue 180 to remind me, please

Done. I hope I did it right?