Ok, I have a 2001 Audi A4 1.8 t Automatic with 121,000 miles.
Every so often could be minutes, hours, or days; cool, or hot engine; the car will just crank and crank, but not start. If I walk away for and hour or so, come back it will start like there was no issue. I bought this car 2-1/2 monthes ago for my wife, and have been working on it since, she hasn't even been able to drive it yet because I don't trust it.
What I've Done:
Fuel pump
fuel pump relay
fuel filter
crank position sensor
coils
plugs
collant temp sensor
K&N air filter
seafoam in gas
I can't figure it out, I have an appointment at the dealer on monday, but would like to see if anyone else has any ideas.
Also, only pending code is po171.(I assume from all of the cranking)
I know there are some smart guys on here who could help, please for all of my sanity HELP ME!

 

no ideas? please help!

 

Have you checked your starter?

If not, pull it and take it to your local automotive store and have it tested.

 

I don't think it is the starter, as it cranks fine, not slow or anything.

 

Crapped up cam sensor can cause starting issues. It's on the front face of the head under the upper timing cover.

 

I can take it off and clean it with brakeclean? Or is it somthing I would just replace?

 

It's a pickup - nothing really to clean. It works or it doesn't. You'd just replace it. That sensor does throw a code when it fails though.

 

I cleaned my MAF sensor today, and so far the car has started about 6 times in a row, hopefully it will keep starting, we'll see.

 

The car didn't start again, so I took it to Audi to see if there were any stored faults. There were a couple, one to to with hte ECU relay, which Audi said could be caused by the ignition switch. I replaced the ignition switch, and ordered the relay. We will see what happens from here.

 

Car failed to start again! The relay will be here tomorrow, Dealer says that it has to be the relay. Any one know where it is located so I can do it myself?