please help guys i have a 99 a4 1.8t that starts when it wants too

some day it will run fine all day next day wont start for a week
i found out that it will only start when i turn the key on the on position and check engine light is lit it will run.. ..but if i turn the key on and i do not see the check engine lit up it will not get fuel or spark

i tested fuel pump by jumping relay it works
i get no fuel pump prime or injector pulse or spark when i dont see the cel illuminated

i changed ecu , cam and crank sensor
i dont know what else to do please help

 

Do you have access to VAG-COM so you can post the codes?

When the MIL is illuminated, does the engine start and run normally?

 

when it doesnt start i have no comunication
when it runs i have a alarm code stored make no sense like every code possible code for the alarm and this cars has factory alarm and no immoblizer to my knowledge

 

I do not understand what you mean by 'communication'. Do you mean you have no codes showing with a VAG-COM device connected?

If that is the case, there is most likely a bad connection or earth (ground?) somewhere on the vehicle.

 

no communication will not connect

 

I too don't know what you mean when you say "it won't communicate". And when you say it doesn't start unless the CEL is on, are you really saying that sometimes you turn the key and there is no power and no dashboard lights? If so, I'd say swap out the ignition switch. But I'm just not quite sure what you're describing here.

 

+1 on starting with the ignition switch as they can sometimes be the source of no-start conditions.

 

the vag will not connect to car and not all the light only the cel (check engine light ) will not come on ... i check the back of ignition switch with key on all gets power and grounds and still no cel light when keys on the on position
when i leave the switch on for a long period of time u will see the cel start flickering and if stay lit the car will start

 

If the Malfunction Indicator Light (MIL), often referred to as the 'check engine light', is not coming on with the ignition in the 'ON' position, there is an electrical fault with the ignition switch or wiring.

You said in another post that only the alarm system codes are stored in the memory when checked with VAG-COM, but no other codes are present?

Has this vehicle been in an accident and recently repaired?

 

I know this was an old post, but was this issue ever solved? I'm having the exact same problem.