Im working on a 2001 tt225 narrowband 6 speed to wideband conversion
Ive prepared a 032hf jetta wideband ecu with a 018bb wideband tt flash file and copied the orignal narrowband tt 95040 to the new jetta ecu to match cluster key code and immobilizer. I have also modified the 018bb's mlhfm to match the narrowband maf's mlhfm. When we added the wideband harness conversion and swapped to wideband o2 sensor with the new ecu we got it to crank and start for 2 seconds but it wouldnt keep going. Giving it a little gas made the revs go up but it would always die out. I tried a 018bb ecu file with egt codeout and narrowband 512x1 mlhfm table and it did this. I also tried a stock 018bb bin and a 018cj bin both with the narrowband 512 table copied over. They all ran for a second then died out. We are just gonna buy the wideband maf so we can try a stock bin but im wondering if something else is stopping us from running. There were no codes pending or saved. One odd thing i could see in live data on a scan tool was that %load as a data pid was 100% when the car was key on not running. Hopefully theres something here im missing.  Thanks for reading.

What he said. Immo3 flash must have immo3 eeprom. Vice versa, also true.

I have finally pulled off the wideband conversion and ill summarize what i had to do.
-Added wideband harness from unitronic per uni instructions. Or you can follow some how to's and make your own
-Used a stock 018BB bin on a 032HF jetta wideband ecu
-Read the 95040 and Immo off the file. re-wrote to 95040
-a plastic tab had to be cut from the ecu so that the original narrowband tt harness could click onto ecu. We actually pushed pins out trying to connect to the ecu and found the plastic alignment tabs were slightly different between ecus and modified with a razor. Works great now.
-Deleted vvt via CDNWS (original 3, set to 0) Also coded VVT out of eskonf(could also resistor to avoid eskonf but CDNWS needs to be set to 0 regardless.)
-Set catr, cats, and cdats all to 0 for egt removal
-Removed pin #61 from ecu harness to stop radiator fans pulsing. Found on another thread.
-I did not swap to the new maf for the wideband file so I copied the mlhfm table from a narrowband and pasted it into the new bin. It hasnt set any rich/lean codes yet so it must be close enough. Im gonna get some good logs this weekend.
That swap worked with 0 mil lights and started just fine. No matching via vagcom needed as long as you immo off.
Some minor tweaking of BTS fueling may be necessary now that the EGT is removed.
Thank you to nefmoto and the users on here always helping me out where i get hung up. Knowledge is a wonderful thing to share and not many people share so thank you all for your time and effort. Hopefully my little compiled list will make it easier for the next noob trying to accomplish the same thing.