Megasquirt installed - no CAS being picked up
 

Hi guys,

installed my home made megasquirt (ms2, v3) on the weekend into my 94 eunos roadster.

everything appears to be working apart from my CAS signal.

Now... ive got the coils still unplugged. Any ideas if this provides power to the CAS at all? I'ved looked over the following document (pages 8 and 9) but cant figure it out.

ive got coolant temps/TPS etc. so its just CAS im missing and im getting annoyed at myself for not being able to figure this out.

Cheers
Ross.

The coils being unplugged does not affect the CAS in any way.

How did you wire the CAS to the ECU, and how are the pullups configured?

Hi Joe,

followed the DIYautotune MS2 mods, but because we weren't using a stepper motor IAC we brought the CMP signal in on pin 25 (IAC1a)
How to MegaSquirt your Mazda Miata

using pin 25 on the DB37 (labeled IAC1a on the board) to bring the CMP signal in, then it's jumped across the board as per the instructions in the DIYautotune article

just to note, when i cranked the engine, i had a reading of 175 for a split second. I've since checked the battery and it was showing 11.3 volts. so its on charge, However id still expect the CAS sensor to work if the engines turning.


Cheers
Ross.

I hate trying to troubleshoot problems like this via web postings... Do you have access to an oscilloscope?

11.3v sounds extremely low, but I assume it's not so low that the ECU is resetting while cranking. If you haven't already removed all of the spark plugs, this will allow the engine to turn over much more easily while cranking (and, thus, decrease the voltage drop from the starter.) Probably not the core problem here, but it'll help you out.

Can you upload an MSQ for us to look at, as well as a datalog of cranking?

Hey Joe,

Yeah i fully understand, its one of those jobs you need hands and eyes on, but any hints would be appreciated. I do not currently, but worst case im sure i can borrow one.

its 11.3v when not cranking, so imagine a little worse when i am. I've got new plugs to go in anyway so ill make sure i remove them, thanks for the tip.

Sure, will do. At work currently, but should be home in 3 odd hours. So will run a log.

Thanks
Ross.

11.3v floating is way low. I have no idea if it's the actual cause of your problem (probably not) but just to be safe, give that battery a charge and repeat the test with the plugs removed.

Hi Joe,

I gave it a try with a bit more charge in the battery and plugs removed (see attached), it flickers between 0-65-165-350, Not sure if thats normal operation.

battery is nearly fully charged so will test again shortly.

FYI the coils arnt unplugged, just the loom connector to the coils on top of the cam cover. Hopefully this isnt my issue.

Thanks for your help.

Ross.

So, Had some help off a friend viewing the log file. So im getting error 38 during cranking, which according to THIS means "37, 38, and 39 Pattern does not match 4G63"

Also squirt isnt powering off/resetting during cranking, so one less thing for me to worry about.

going to run a composit log tonight with the fully charged battery.

Also made the following changes:
1. set map and bars sensors to MPX4250
2. basic log / general settings > set view to Centigrade
3. turned off launch control
4. turned off boost control
5. turned off flat shift
6. EGO set to single wideband (step size 1%, authority 20%, ignition events 16 - come on after coolant temp of 50c's)
7. injector dead time set
8. PWM current limiting turned off
9. enabled fuel cut/overrun

Just an update,

Turns out the power i was using in the engine bay wasnt 100%. i've now installed squirt using the stock ECU power wire and everything is now ok. during this we found my coils were wired backwards squirt end (so swapped leads over and she fired up).

Just missing my tach now for some reason.

Update again:

Tach now working (put a 1k resistor between the -ig and +b in the diagnostic port in the engine bay).........

now to work on my fuel tables :-)