Flat Battery Ecu Limp Mode Or Backup Mode ?

[d rangd]

ive just gonbe to start my car after it sitting for a few weeks and it had a flat battery....it wont start and I cant figure out why..it has aftermarket ecu with cdi, disconnected vct (fixed cam gears)...it has fuel pressure and new plugs and is sparking fine...im wondering if the flat battery has caused some kind of default tune or ecu settings that are stopping injectors from opening? im wondering if there is a quick fix or is this a job for a tuner? MERRY XMAS!!

[Dillz]

After market ecu? what one?

I would normally just say re flash and try again, I've never heard of a flat battery changing anything but your clock.

[d rangd]

autronic ecu autronic 500r cdi...I cant work out whats going on last time car started first crank, but has modified crank sensor also...something might have coincidentally stuffed up but I think its to do with flat battery...

[Dillz]

Geez over my head mate, sorry. Surely someone will be able to help you out, might just take a bit.

[qik1]

merry xmas Quinn,

By any chance did all the lights on the dash still come on but it woulldn't winde over.

Mine ever since the battery was put in the boot has been hard to start as in it winds over slow but always started but yesterday while the mrs took the car for the first time the bloody thing wouldnt start, all the lights on the dash came on & she said the fuel pumps primed but it would even crank over.

She said it was hard to start when she originally picked it up & dave did mention it was getting hard to start but after she did a few stops starts it gave up the ghost but the worse part was it was in the middle of toowoomba. I'm at work so I couldnt do too much but as soon as I can its going into 6boost for them to go over it all & have all the little things finished off but its still a nuisense as its sitting in my inlaws frint yard.

Any ideas for now what it might be??? The battery might be getting abit sad as it has sat for bloody long periods of time ever since it was put in but could also be the starter motor, who knows???

[d rangd]

merry xmas john nah she cranks over hard, got oil press, fuel press, ignition, just not firing so must be fuel injection problem im guessing....ill look at getting it taken back to a shop after new years AGAIIINNNN, prob get race tune and the last of what I had planned done too I suppose but after that ill probably fix the damn thing with a match haha

[supercharged88]

Hi mate,

do you have a laptop with Autronic SM4 software loaded and do you have the Autronic PC cable if so I can probably help you out here.

Also if the battery has run dead flat there is a possability the ecu has lost its TPS settings and you may have to relearn the TPS open,closed values.

Let me know if I can help.

Regards

Dave.

[d rangd]

gday dave, no software! its definately reset something, not firing at all...il take it to a shop next week and hopefully get it sorted..

[supercharged88]

You can download SM4 version 13H software from Autronic.com.au.

But you need a PC cable to connect.

I can instruct you on how to make one if you wish, you only need a DB9 connector and a 3.5 mm stereo jack and a length of 3 core wire.

The reason for this is you can hook up the laptop and connect to the ECU and check for error codes and look at live cranking data to help sort the problem.

Otherwise, on the end of the SM4 is an LED, turn the ignition on and count how many times the LED blinks, this is a diagnostic LED.

Long blinks are units of 10,

Short blinks are single units.

EG : 2 LONG BLINKS = 20

3 short blinks = 3

this would equate to fault code 23.

If the battery has run flat and the TPS is set up as FIXED in the software, not AUTO then the TPS will need to be recalibrated.

Without a laptop and software do the following to recalibrate the TPS.

TURN THE IGNITION ON,

DISCONNECT THE TPS CONNECTOR,COUNT 10 SECONDS.

RECONNECT TPS (LEAVE THE THROTTLE CLOSED) COUNT 10 SECONDS

THEN HOLD THROTTLE WIDE OPEN (100%)COUNT 10 SECONDS,THEN RELEASE THE THROTTLE,DONE.

The ECU only takes a few seconds to learn the above values, I only advise to hold for 10 seconds to make sure it has learnt the values as you dont have a laptop to watch these values load up.

You also need to remove your sparkplugs and check they are NOT WET with fuel.

The CDI will shut down at voltages below approx 9 volts and not produce any spark when cranking with a flat battery.

However the ECU can normally still fire the injectors.

If the plugs are wet the CDI will not fire them.

Just a word of warning NEVER be tempted to crank the engine without sparkplugs connected and grounded.

If you must crank the engine disconnect the CDI.

Cranking the engine with no load on the ignition circuit (CDI) will result in CDI failure.

If the plugs are wet,disconnect the CDI UNIT, disconnect the injector connectors and crank the engine with the throttle held wide open (100%) to get rid of any residual fuel in the cylinders.

Fit new plugs (BEST OPTION).

Reassemble, dont forget to reconnect the CDI, crank the engine and see what happens.

Do not be tempted to pump the throttle as cold start multipliers on base fuel and throttle enrichment will be applied leading to more flooding.

If you hold the throttle above 90% (default value) when cranking the injectors will cut out to aid in flood condition restarts.

Woth giving the above a shot, if it works your back on the road.

Let me know if you have any error codes (LED FLASH CODES).

Hope this helps, you've had enough dramas with your beast.

Good luck, regards

Dave.

[d rangd]

cheers dave I only just looked back but im going to give it a go, I will take it back to the shop as a last resort then, may aswell try myself and learn a thing or 2! ill post back with what happens, just hope the ecu isnt too hard to take out I know its up under the dash/console area somewhere