Faulty ECU

[ThatGUY]

Today I was broke down on the side of a motor way which ended up being a faulty ECU; of course with heavy rainfall.

My car as been running spot on the past few months. I have replaced nearly every sensor over the past two years. About two months ago I also had a spare ECU socketed and chipped. I thoroughly enjoy driving the old machine.

I have had no troubles or warning signs. While I was getting into traffic at around half throttle the engine shut off without notice, no shake or noise. I noticed the battery light was lit. Pulled to the side of the motor way and started to go through the basics. After fettling with all my connection I decided to pull the ECU and have a look for anything loose. Mainly after coming across this thread: Engine died battery light. I stuck the ECU back in and the car fired up. Yes. At this point I still thought my issue was due to a bad G40 hall sender. I managed about 1 mile before it shut off again. After an hour of searching the forum I asked a buddy to pick me up so I could gather tools and supplies from my shop.

Back to the car I swapped out the G40 sensor in no time which impressed my buddy. But I soon found that didn't produce a running engine. For the hell of it I grabbed a spare ECU from my shop; and with nothing to lose I swapped them and bam she fired right up.

Many thanks to Lloyd for post the solution to his problem.

Andrew

[ThatGUY]

What should I do about the ECU?
Should I open it up and inspect it?
Should I send it back to the shop which installed the chips?

I am going to contact the shop; at minimum I hope to get a reply. I supplied the ECU which was working fine before the mods. I am not assuming the problem was created from them, but I did just spent a decent amount of coin for the service.

Andrew

[vag_noob]

From my experience, before you touch the ECU. First check your carpet around the ECU for dampness. Second check if your cowl drain is blocked. Third remove the T55 Motronic ECU connector and remove the plastic cover. If there is any corrosion you will see green dust and copper corrosion on the exposed part of the wire at the crimp joints. If you see corrosion on the wire inspect the wire for a break.

I had the same problem recently. Last year my carpet flooded due to blocked cowl drain next to heater box and car started to run funny. I had to take out the whole carpet and found a huge puddle of water under the carpet. After I dried the carpet it was good, except when it rained. I would get a funny idle even 1 almost year later.. Carpet is completely dry, no leak.

I replaced ISV, switched coils to 1.8t coils and harness... didn't fix it. Turns out I had minor corrosion on the ECU board and some corrosion on wires at the T55 plug to the Motronic ECU. One wire was so bad that it broke when I removed the plug from the housing to inspect it. I suspect this corrosion, weak wire was the cause of the funny idle.

There was also some minor corrosion on the underside of the ECU board, I had to remove the ECU board from the housing to find it (but I only did this because I chipped the ECU). After I chipped the ECU it was fine but I removed the ECU again to clean it with compressed isopropal alcohol, and at this point I damaged the ECU and have had to find a replacement.

[vag_noob]

When I had the water in the car, I had the exact same symptom that you describe, the engine would cut out when driving. I would pull over to the side of the road and wait a few minutes, and the car would start and run fine as if nothing was wrong, I would drive 1 km or so and the engine would cut out again. I suspect this is due to a short due to moisture as this problem disappeared after a removed and dried the carpet.

[ThatGUY]

Thanks for the reply.

My car and ECU is very dry. I did inspect the wires in the ECU plug; everything looks good.

On the side of the motor way out of desperation I popped the ECU open and pressed on both socketed chips. That was right before it fired up.

I think my ECU should be checked out. I'm not sure how to or if I'm qualified.
Could I put a piece of foam between the two boards of the ECU? Small ones just to put pressure on the chips; would that increase heat and cause failure?

[newsh]

Inspect the chip sockets carefully with a strong light and a magnifying glass, you may have a 'dry' solder joint on one of the pins.
I think you should be ok fitting some foam to hold the chips in place, I've done this before with no issues.

[Dynasty]

Try to reinstall the original chipset...