As ECU tuning experts, we don’t only work with tuning, we also work with undoing bad tuning from all the other companies out there. Sometimes we even get involved with the main dealerships when they have a problem restoring an ECU to stock.

Sometimes an ECU can’t be restored even with official software. In this case a Bosch EDC17C74 from a Volkswagen Tiguan was corrupted after trying to update with a genuine VW tool. After this the car wouldn’t start and the equipment would no longer connect to the ECU.

We connected to the ECU in bench service mode, and thankfully we could still connect to it without needing to go to boot mode. After reading the flash memory our equipment gave several warnings that the file was likely corrupted.

We imported the software in to WinOLS and then compared it with a guaranteed original, the results were actually quite peculiar. It was clear at which point the update failed because the flash memory suddenly because corrupted and very random, the changes were outside of the main maps block which is actually very unusual.

Here’s a view of the maps area, you can see that the update didn’t get as far as over writing this block so there are still many changes. We can see here the typical novice tuner automated tuning style that we see in many ECUs, focusing on changing rail pressure when it’s not essential to change for this model of ECU.

Here’s another tell tale sign that the previous tuner was inexperienced, they increased the injector duration map, this should never be done. The injector calibration maps are precisely calculated on a flow bench by the OEM. What do you think happens if you increased the injector opening time? Injected flow increases, but the ECU DOES NOT know about it. Why is that bad? Well, think about the DPF. How can the DPF remain clean if there’s always extra fuel being dumped in to it? Also this gives the wrong injection timing because the fuel quantity is wrong. Stay away from tuners who get their power gains like this!