Help! Car won't start!

[S2central.net]

Don't be fooled into thinking that VAGCOM will show up such faults... Its great when it detects a sensor is open r short circuit, but almost useless when the sensor gives bad signals. I hate to say it, but you might be looking at some sensor replacement therapy here to see if you can find the root cause.

Jas recently had a fault in his loom, that didn't blow a fuse, which caused bad running - you might have something similar - needs a breakout box and the right schematics to buzz out the loom from ECU to all sensors.

[Rusty]

That's what I was afraid of! I spent last night dreading checking the 40 or so wires!

Might just have to take it one sensor at a time... I get the feeling this one is going to take some time to figure out.

Car rus OK but the fluttering boost is one of the symptoms of something that is awry and I'm damned if I can find it at present.

[Rusty]

Borrowing some crank hall senders to try out (G4, G28)... G40 can wait as I don't want it to be broken

[saltinot]

Before you go though too much trouble with replacing sensors and whatnot you should open a fuel line to verify that you've got pressure. A failed fuel pump will cause similar behavior.

[Rusty]

Cheers, I should really check the fuel system at some point. Fuel filter is 10k old and seems to be running OK at the top end where I would expect a weak fuel pump to cause problems.

[S2central.net]

Would be worthwhile checking pressure just in case... But then you have 55 pins and umpteen sensors to check first

Check that MFTS R-pin is above 2V

How fresh is your WGFV ?

Did a differnet MAF make any difference ?

Make sure to reset the ECU when swapping sensors - so that it has to relearn evrything each time - dont want it holding onto old bad info.

[Rusty]

Car is still running a bit off, every now and again it wants to fly like it used to but something's telling it not to... perhaps it's got split personality disorder or soemthing. Hope to get it sorted soon.

[Acidburn]

Is it possible with vagcom to actually drive the car whilst checking for errors etc, kinda similar to live mapping?

[Rusty]

Hope so, just need the time to do it!

[S2central.net]

Sounds like electrical gremlins if its intermittent like that.

Yes you can run with VAGCOM - happily logging data all day if you have a big enough disk... Problem when driving can be the laptop going to sleep on battery - suggest you run with a mains inverter from your ciggysock or tweak the battery settings to prevent sleepmode.

Next problem is keeping laptop in place while driving round corners... Really needs a co-pilot as they can place markers in the datatransfer at key points for reference.


paul

[Rusty]

It's only happening on full boost so perhaps the excessive g forces will pin the laptop in place in the passenger seat

[Acidburn]

Maybe on cloth but probably slide well on leather

[Rusty]

Off to All Audi on Saturday to have a play with Vagcom.

[Rusty]

Swapped the speed sensor and crank sensor last night and the boost at 3.5k is still playing silly ******s. This is getting rather frustrating to say the least. The car's not running badly just not quite right and I like things to be right!

Drive to work was fun this morning though... so not all bad.

[Jas11n]

Noticed you asking about hall sender Andy, if it fails to provide a signal whilst the engine is running, it'll limit boost and retard ignition