View Full Version : 94 Audi 100 s 2.8 auto no start


pistonmaster
09-07-2008, 06:13 AM
Hello everyone I'm at my wits end. My Audi ran fine one day and won't start the next! Here's the story. I power washed the car and engine at work and two hrs. later I drove it home and shut it off. Later I ran down to the loacl drive through and back. The next morning crank, no start! I hooked up my Vag scope and got a code for no power to the crank and cam sensors.I cleared the code and it hasn't returned I also found no power to the injectors and ignition pack. I removed the battery to charge it after cranking it down. A few days later I installed the battery,and the car started right up! I shut it off and no start right away. I thought mabey fuel pump relay, checked ok. Have no idea where to go next. I am a diesel mechanic so I have all the tools necessary, just need direction. Any ideas?

The_Hamster
09-07-2008, 06:39 AM
http://www.12v.org/maintenance/dtc.php

DaveInSaltLake
09-07-2008, 07:31 AM
here's a good link to research your codes (see below).

so are you currently getting power to the ignition system? spark at the cylinders?

a faulty cam position sensor will typically cause intermittent no-start problems, but it will definitely set a code. recheck codes because not all codes will set a CEL.

another thing to look at if you're not getting power to the ignition is the POS 'power output stage', another finicky part. it's mounted on the right side of the firewall. Search POS here for loads more info.<ul><li><a href="http://wiki.ross-tech.com/index.php/Main_Page">http://wiki.ross-tech.com/index.php/Main_Page</a</li></ul>

pistonmaster
09-07-2008, 08:25 AM
I no longer have the codes written down., it's been a few weeks. It did say that the cam sensor b+ was shorted or no power. Tested found no power to cam sensor. Also no power to ignition system. I tore apart the interrior and now have access to every fuse and relay panel in the car, as well as every ecu. Looking up POS now.
Thanks

pistonmaster
09-07-2008, 08:33 AM
Also since initally clearing the cam sensor code I have had no cel or return codes. The cel is on or flashing while cranking even though the unit won't start. I got the unit running twice since clearing the code. Both times it happened after disconnecting the battery, charging it, and reconnecting it after a few days. Each time it ran, not great, but enough to drive. I had full throttle response, but idle was slightly rough, and again no new codes. I currently have the battery disconnected and charged.

pistonmaster
09-07-2008, 08:36 AM
Is flashing the same as clearing codes? If so I've already done that, and got the car running twice with no new codes.
Thanks

austinado16
09-07-2008, 08:40 AM
And blow them dry with compressed air, including down into the rubber boots, which will also be full of water and soap.

Then go buy a can of WD-40 and use it's straw to spray into and basically fill up, the connectors and boots.

You should have a running car after that.

pistonmaster
09-07-2008, 08:58 AM
I initally thought the same thing. While cleaning I tried not to directly shoot any connectors some were in the way. All were cleaned and reconnected. But it's been awhile I'm gonna do it again, right now.
Thanks I'll let you know what happens

ricoblanco
09-07-2008, 09:04 AM
reading the codes using <a href="http://12v.org/maintenance/dtc.php">this method</a>. I see you have a reader so this isn't necessary, but now you know! :-)

pistonmaster
09-07-2008, 10:09 AM
Well I unpugged every connector and cleaned them with Permatex electrical contact cleaner. I reconnected the battery and, no change.
Thanks

pistonmaster
09-07-2008, 10:11 AM
Duh I'm a moron! I knew that! But I didn't know how, in an Audi till now, Thanks!

DaveInSaltLake
09-07-2008, 11:06 AM

pistonmaster
09-07-2008, 12:48 PM
No I don't. I'm thinking I need to test the POS and the cam sensor. I've already removed the POS.h

austinado16
09-07-2008, 10:39 PM
If you've got all 3, then I'd look at the cam position sensor being full of water.

Had a Passat come into the dealership once that would die on decelerating right hand turns. After umpteen hours of diagnostic time on it, and calling the VOA Tech Line, I finally removed the MAF and shook it. *slosh-slosh* Cut the factory silicone sealant out from around the lid covering the circuit board and found about a tablespoon of soapy water inside. Guess what our detail guys had done to the car just prior to it being sold as a used car?

pistonmaster
09-09-2008, 06:09 AM
Got AIr, Got Fuel, No spark! I'm told that the cam sensor controls the POS during cranking. So if the cam sensor is "fouled" then no spark. I initally had a code for the cam sensor to begin with. I'm thinking that you are correct,atleast in that the cam sensor is the problem. I would not be surprised to find it full of water. I'm going to replace the cam sensor and the POS and see what happens. I will update when I do. Thanks for your help!

DaveInSaltLake
09-09-2008, 06:12 AM

austinado16
09-09-2008, 06:37 AM

DaveInSaltLake
09-09-2008, 07:07 AM
throws a DTC in the ECM. A POS won't throw a code, IIRC.

pistonmaster
09-27-2008, 12:54 PM
Thanks all for your help! It is now running! After all of this it was the cam sensor I replaced it and now she starts. I did not find any water in it but I did find a lot of oil residue. I can't dismiss the power washing but I'll remember this always. I am glad it is now running! Again thanks everyone for your help!

austinado16
09-27-2008, 05:06 PM