Hi folks,

Not so much of a question but a share of my experience with my first ECU read/modify/flash experiences. Two 2001 Passat 1.8 turbos in my family. I've got a saloon sport and also an SE estate. I had my saloon professionally remapped several years ago and the company that did it has long since folded. After reading a lot of the guides and various posts on here I decided to have a go at "remapping" the estate. Well, I say remapping, I mean taking the map off the saloon and trying it on the estate. As luck would have it, both have the same ME7.5 ECU (4B0906018CG). I thought this would be a good place to start as I could compare the base map with the saloon's modified map and get to grips with exactly what has been changed.

My set up is using an Win 7 HP mini netbook and a generic VAG-COM cable that I bought not for VAG-COM but to actually flash my Triumph Daytona with a new map using Tuneecu (that's another story). So night before last I read the existing maps from both Passat's and did some initial comparisons in Tunerpro. The altered map on the saloon had the NO READ flag set so had to modify that with a hex editor to be able to load it. Being quite cautious, when doing any nefmoto operation I ran the laptop while hooked to the mains and also had another well charged battery hooked to the car on jump leads.

After reading a few more posts on here and amending the checksum on my saloon's map after removing the NO READ flag using the ME7SUM tool I decided last night I'd go for the big flash on to the estate. It didn't exactly go 100% to plan I must admit. I decided first thing I'd do is reflash my "readable" map back on to the saloon and prove I could make the process work before touching the estate. That went quite smoothly and all was good. I then turned my attention to the estate and flashed it with my ever so slightly tweaked saloon's map. Again, went on super smooth. Feeling confident I took the estate out for a quick blast and all seemed well it was now pulling like the saloon until I turned around to come home. Booting it through 1st, 2nd and 3rd it suddenly wasn't running well and the engine light was going berserk and I crawled back home in a very juddery fashion. Clearly, it was only running on 3 cylinders but in a panic I thought it was best to back out and revert to the stock map. This, however, failed. I had two attempts at writing the original map back and had time outs mid way through. Quite possibly the worst thing you want to happen as a noob! I can only chalk this up to my laptop/cable misbehaving. Luckily, a restart of the laptop and I was able to restore the original map without having to resort to the MPPS cable I bought as a backup.

After the flashing drama, the estate was still only running on 3 cylinders so I came to the conclusion that I had an unfortunately timed coil failure which I managed to prove my disconnecting the coil packs one at a time to see if disconnecting one had no effect. Yep, probably could have determined this with an OBD fault code but I was a little panicked by this stage! Haha. I had spare set of coil packs so replaced the failed one and massive sigh of relief, HMS passat-a-bus estate as it is affectionately known was running good again.

Not to be beaten, I then went for a second attempt of deploying the modified saloon's map. This time, it all went well and I drove it about 10 miles last night with no issue. It seems persistence does pay off although there were some "oh shit" moments along the way. Since flashing I'm keeping an eye on the fuel trim levels. Long term still at 0 and the short term varies up to around 10% so hoping this map should be OK on the estate. I should point out that mechanically both use identical components except the saloon has a high flow air filter in the air box.

Now I have a little experience with the flashing process I'm going to start disseminating the differences between the stock map and my paid for custom remap. If anyone would like to see the maps I'd be happy to share.

Anyway, that was my first experience, apologies if you got bored reading it! Thanks to all the folks that have provided guides and info on here; I wouldn't have been able to do this otherwise.

Just a little sore.