Hello everyone! I have a problem with my A8 QUATTRO 98'

After running perfectly well for a long time, one happy morning it just died. it cranks but wount start.

i checked spark plugs, replaced the fuel filter, fuel pump its working, fuses - all is perfect and then J271 relay which appeared not to be clicking. so i bypassed the relay and the car started.

but then when i bought a new exactly the same relay it didnt help. same stuff, car cranks but doesnt start.
I tested it again by bypassing the relay and it starts.

i assume that the problem is with ground but have no idea how to test it.
also i wonder if a could drive with the wire instead of relay.

the scanner is showing: Main Relay (J271): Electrical Malfunction P1517

here is how it looks like.



and a bypass.


any ideas?
would apreciate the help!

PS
I also read this from M5S5 "When some of these cars are started the ecm looks for a signal from the cranks sensor. If it missing it will not activate the fuel pump relay preventing it from pumping fuel in case of an accident where a fuel line gets ruptured."

could it be my case? is it the crank sensor? how can i test it?

 

anyone?

 

Have you scanned it with VCDS (VAG-COM) or just a "code scanner" ?

Could be the crank sensor from what I've read of others having similar problems.
Might also be fuel pump(s).

A full scan will give us better info....

 

it was just a code scanner.

 

bentley says Check the fuse for the ecm power supply relay J271

that's what it says and i hope its that simple

look for a fuse marked ecm power supply or j271
it is under the hood
remove the black plastic cover near the windshield and it is located on of the passenger side to the right of the ecm

The relay is switched on by the ecm with ign on
so either the fuse is bad,
you have a bad wire
the connection at the ecm is bad
or the ecm itself is messed up

you will need a bentley to start testing everything

 

so this black relay on the photo is J271 relay and i bought a brand new one. so i agree the problem could be with the wires that cary low curent that click J271 relay. or ecm itself.

i tested the wires and there is no signal at the moment i start the car.
somebody told me that it has to be a burned fuze. do you guys know which one could it be ?

 

I'd use a fuse tester.

They are cheap at any auto supply store and have points that press onto the fuses.

Actually found a blown fuse I didn't know I had while looking for another blown one.

 

good idea! thanks!