850 t5 M4.3 ecu fail after soldering

[t1mda]

Hello, 

Yesterday I wanted to prepare my ecu for diy tuning. 

So I soldered out the original eprom, read the bin, programmed it to a new one (no changes just the original file) and soldered on a socket for the chip. 

Since then the car starts fine, idles like normal and even revs but as soon as I start driving, the engine dies, the radiator fan switches off and on randomly and the speedometer goes crazy. If I plug out the ecu and put it back in it starts normal again and then the same. 

The car is a former 2.5 20v manual with an engine out of a Euro 850 t5 automatic, so it currently runs with the auto ecu, like a manual swap. 

The problem stays even after desoldering the socket and soldering the original eprom back in. I personally can't see significant damages to the board. On the other hand I soldered some abs units and other things before, but I'm not a professional. 

So my question is if this sounds familiar to anyone, maybe I made a typical mistake and there might be a possibility to save the ecu. I found a spare one for 80 € but I wouldn't want to ruin it too. 

 

 

 

[Byte_My_Void]

i think u need to post some good quality photos.

no one knows your actual skills and equipment that uve used. maybe firmware was damaged by overheating old memory, or its pcb damage (route detach).

What kind of flux uve used. some fluxes must be washed off to prevent glitches  and so on.

[ArMiGer]

On first place, why did you resolder the M4.3 ecu chip? You can read and write the 64kb M4.3 ECU just with software and cable without touching the board. If you have OBD it can be done in the car. If not you can do it on the bench. The only thing you have to do is a small modification to the cable.