Battery died, now car starts but does not run.

[A2VW]

My car battery died when the radar was left plugged in, now after attempting to jump start the car, and attempting to start it with a charged battery; the car will go through the normal startup and cranking, fire up, barely hold idle for 2-10 seconds, then wont run. It will just die if the throttle is pressed.

All visual displays on the read out appear as before, so I dont know if i should start messing with VEMS things I dont know about!

Can i assume I have, air, fuel, spark, because it starts?

Where should i start trouble shooting?

[Bat]

Hi,
I'd start by  looking at the fuel system. It sounds like no fuel, is the pump running?
Cheers,
Gavin :)

[[email protected]]

As Gavin says it could be the fuel pump - probably the relay.  Also its worth noting the fuel PWs as the car dies.
Pull the plugs directly after because it could potentially be too much fuel or the spark dropping out.

When you say there are VEMS things you dont know about - how did the system get setup on your car?

Cheers

Rob

[A2VW]

The VEMS installation was done by a reputable Canadian VEMS dealer, which I live about 300km from. We've been emailing back and forth and we're trying to troubleshoot one step at a time. I posted here to open up the conversation, and to give us both a reference thread.

I wanted to rule out any possible fuel starvation issues first. I tried another fuel pump relay out of my daily driver, and no difference there. I changed the fuel pump and filter, no difference there. (loaner parts, so Im not throwing money away!) I am indeed getting fuel and have confidence that the issue is not related to anything in the fuel delivery. The pump audibly runs and makes pressure to the fuel rail.

Next I got out my old laptop and ran Megatune (VEMS 1.0.73 version) to look at things on the display like I have done long ago in the past. (I haven't changed any settings or values)

I noticed a few things I hadn't seen in the past, heres what I saw.......

--While in Mega-tune with the car not running, just turned on, Ill see the SPARK ANGLE and PULSE WIDTH displays do sporadic drops in value, then ruturn to normal, then randomly drop again. (I think this may have been an old FW bug, but Im not sure)

--While viewing real time display with the car not running, "VE" is running through random numbers, like in a loop.

--While watching the LCD readout in the car, as soon as the car gets started, the screen freezes and values don't change or update. When the car dies, the screen resets and refreshes the values.


Ive been careful in Mega-tune not to change any values or "Burn to ECU" at all.
 
Its not my daily driver car, so I'm surviving without it. If worst comes to worst, I'll have the ECU bench tested by mailing it out.

[A2VW]

SUCCESS.

Reloaded firmware, and things were back to normal.

Thanks to those who helped me out in this post,

and thanks Dave H, Marcell.