Michael Espiau

1998 audi a4 quattro

I recently just bought a great driving beautiful B5 A4.

Randomly a couple days after buying it, It just wouldn't start.

Eventually I went through all the steps to troubleshoot and realized that the fuel pump wasn't priming or activating when I turned the key. I jumped the fuel pump relay and heard the pump kick on and car still didn't start.

I ended up going in my ecu box and wiggled and pulled on the wires just a little bit and then it started up.

This happened at least 5 more times randomly and most of the time (hot or cold) would start up no problem.

Anytime I have driven my car, it has never shutdown or bogged out. The problem only came randomly when I have tried to start it.

It happened again this morning and now I can get it to start at all.

I have yet to look at any codes my car my be sending out. I have to wait for someone to bring a code reader over since I can't bring my car anywhere.

Could it be a bad computer? even though it is fine when it is running?

I'm at a loss...

Prospeeder

Well, Its either a poor connection at the connector, a broken wire at the pin on the connector. or a bad solder in the ECU and wiggling the wires or unplugging and reconnecting restores it for a bit. Its hard to even say which one is at fault. When it wont start, is the engine light come on with the key on? If not, that is like the ECU is not being powered up or grounded. This is a hard one to diagnose, First remove the connectors and visually inspect all the terminals on the ECU and in the connector. If it looks ok. I would be tempted to try another ECU as a test first.

If ECU doesn't fix it, you will now have to get brave, and disassemble the ECU connector with all the main powers and ground and see if one pin is broken where the wire connects. I have seen it only a few times, and it makes no sense, but right at the pin where the wire crimps to it, it just is broken!

Michael Espiau

I know the ECU is getting power, because I was able to get the diagnostic tool to spit out some codes, but the only codes it was throwing was p0411 and p1565... I did research and found that those codes wouldn't stop the car from starting. The diagnostic tool is able to talk to the ecu if it's spitting codes out right? Well... Either way I ordered a computer from online just to get the ball rolling in case I would have to order one.

It's just hard for me to wrap my head around... My car would start and never shut off by itself, but going to start it again sometimes, it would fail. With a broken connecting wire, wouldn't it shut the engine off as well?

While I'm waiting on a new computer, I will definitely try looking at every pin at the connector.

Moving around wires doesn't work anymore, so I can't bring my car to the shop and I am a full time flight student and work full time as well.


Thanks for the response