I have an audi 500sel 93 manual AAH Engine, no fire to the plugs, car refuses to start. checked computer box, 2 crank sensors, modulator, the coils all tested okay and fuel coming to injectors ok. timing is okay.

Bad computer.

Car swings ? It's cranks ! When you turn the key to the start position the engine cranks or does nothing ! No fire on plugs ? No spark ! You want answers to your questions ,get the proper terminology ! You have a crank - no - start condition ! Check crankshaft position sensor , ignition module , PCM - engine computer , coils etc....

depends on the module he was referring to
it could be the ignition control module but it could be either /or both the cam /crank position sensors , the immobilizer module or ECM unit
BUT would be best to have the fault codes read first and then fix the problem/s that are found

coil pack module,underneath the coil packs,or you did not replace the ecm with the new motor,you need the computer that goes to that motor

The coils have battery voltage running through the primary windings, and grounded in the ignition control module. The engine computer signals the ignition module when to cut the primary current, thereby inducing high voltage in the coil's secondary windings and spark at the spark plug.
The computer processes all sensor information, but primarily from the crank position sensor, to determine spark timing.

Hi there, I have Audi 500se south Africa = to Audi 100 2.8 AAH engine 1994 model it suddenly Vanished the ON sign when I turn the ignition to ON position but it still cranks and almost every thing functions apart from it still no voltage from computer box to crank sensor and module. I checked my fuse box n all fuses are OK, can someone plz help me to find ON?

its possible there are multiple coil packs usually one for each bank or one for every two cylinders. Or check for a ignition control module

could very well be a faulty sensor, leaky vaccum hose, bad coil packs, needing of new fuel filter, spark plugs, wires.

Have you checked your fuel pressure to make sure it is good. You can do this with fuel pressure tester on the fuel rail.

Also check every cylinder for spark
If you don't have any spark, or very weak spark, you could have bad coil pack, module, or crank sensor.

You can remove one plug at a time, and place it back on plug wire, place it on top of engine block, have someone else turn motor over well you observe to see if there is spark.

Do you have a service or check engine light on? If so, I would have the engine codes read to pinpoint exact problem area.

Let me know if you have any questions or need further help

if it was activated the button will be pushed out you will have to push it back in to get it to start again. if that don't work then it could be alot of different stuff after you check the fuel shutoff switch check to make sure you hear the fuel pump kick on. if you don't hear it kick on then check your fuses. if you hear it kick on then check and make sure your getting fire to the plugs and if your getting fire to the plugs then it might have jumped time and if your not getting fire then check the ignition control module and your ignition coil. it might even be the crank sensor or cam sensor.

I had a 2002 dodge town and country that lost fire and found that a wire under the fuses box was broken this is the fuse box up front under the hood. I used a test light to see if power was going to coil pack I had a friend crank while i tested each outlet on plug that is when I traced it back to the fuse box. I hope this helps