I have a 99.5 A4 1.8T. No mods.

My story starts a few weeks ago. I went out to my car and upon start I got a rough idle, I recd a blinking CEL (misfire) and pulled a P0301 code. Because of the #1 cyl misfire I replaced the #1 coil pack and still had the problem of a rough idle. While I changed the coil pack I noticed a small pool of oil around the base of the plug. While I was in the middle of engine work I decided to change the valve cover gaskets at the same time. So after I did the gasket and changed plugs I tried to start the car. WOW. The engine would crank, and crank, and crank, but wouldn't even try to turn over. I then thought I had done something wrong. So I put the old plugs back in. Didn't change. Put the original CP back in - no change.

So now I am not sure of how my original problem (rought idle) is related to my new problem (no start), but here is what I and/or dealer have done to try and get my car running again. I replaced the Pwr Output Stage (ignition control module), the Cam Pos Sensor, Eng Coolant Temp Sensor, and the Crank Sensor (Reference or Impulse Sensor).

None of these has helped. I don't know what to do next. A few times I have been able to get it to start, and once it does start, it runs great. Idles great, accelerates great, etc. But if I turn the car off, there is about a 80% chance I will not be able to start it up again.

Any advice is appreciated. I would like to do things in an order that make sense, because throwing parts at this car is starting to add up.

Thanks,

John

 

When it won't start, do you have any error codes?

When it won't start, do you have fuel pressure? If not, maybe it's the fuel pump relay?

 

I don't have a CEL, and I am unsure if there are any codes, but the dealer had the car and said they aren't getting any codes either. We thought it was fixed with the cam sensor, but it only started the few times after installation. Then it was back to its old self.

I have not checked fuel pressure. Is there a post on how to do that? And why would you think that it is a fuel relay problem? Wouldn't the problem show itself all of the time? Once started, the car runs like a champ.

 

sounds like the ecu and the imoblizer is loosing the code meaning that it will let you crank but no fire and shutting the fuel pump off.check these out and let us know.i used work on audis a4 b5 alot.

 

One quick check you could do to rule out the fuel pump relay is just turn the key to the ON position (not start), and listen for the fuel pump, it should hum for about 2 seconds whenever you do that (it primes). If you don't hear it, then that could take you down a specific path.

 

North American Audis didnt have an immobilizer yet.

 

correct me if I'm wrong if it were a fuel pump issue he wouldnt be able to start his car at all it wouldn't be a temperamental thing. I have a bad fuel pump in my other car right now and you can't even get it to start... again I may be wrong but if a bad fuel pump you wouldn't be able to start at all.

 

MAF? check for fuel too

 

This was just happening to me. Had heavy misfiring. Shut her off, changed plugs and it wouldnt start. I added some oil and it started up! I've heard that with low oil these things wont start.

Also, try just cranking it and cranking it and cranking it. It'll get faster and faster till VROOM. Make sure your battery cables are clean. Good luck!

 

Not sure how a relay most often fails, but I would think the relay could be intermittently bad. Say you turn the key once, it trys to energize and cant, try the key again and eventually it does and is able to stay energized? I would at least make sure to listen that it is turning on like someone mentioned previously.