I own a 2001 A4 1.8T Quattro that was rolled and totaled. The engine is still good in it, so, being told that the engines are interchangable, I bought a very nice 1999 1.8t A4 Quattro, that had a blown engine. Well, I just received a call from my mechanic, and apparently if they are interchangeable, there are many changes that would need to be made to the 2001 engine prior to being able to making it work in the 1999. Please tell me that someone has some good advice.
PLEASE ANY ADVICE OR DIRECTION TO A LINK THAT HAS INFO IS MUCH APPRECIATED. I apologize if this is a repeat post.

 

Do you still have the blown engine from the 99? What went wrong on it? You should be able to mix and match pretty easily. The 99 will be drive by cable, where the 01 is drive by wire. Depending on what engine codes they are, the water pump and belts will be different. The 01 is probably a vvt head which is very easy to get rid of if you can swap the 99 head onto it, provided thats not the "blown" part. The ecu will be different, so i believe you will need to use the wiring harness and ecu out of the 99. They are definitly very swappable, the sensors and features will just be different. Im sure someone more knowledgable about the differences between the two will chime in. In the mean time, you might want to check what engine code is on each one (tab on the front drivers side of the head) and what ecu part number each one is so the guys on here can more accurately help. Good luck

 

Thinking about it a little more, you might have to swap out the gauge cluster to run the newer ecu in the 99 properly. Also the 01's should have map sensors where the 99 only used a maf, so those will both need to be swapped in too. So if im not mistaken, you will need to swap in every sensor that the 01's ecu controlled unless you can delete or change them with a vag-com. Sounds like your mechanic will have a fun time with alot of wires lol.
Sounds like a good time to do an SAI block of also.

 

FasterA4 is right. There's a lot of changes that would have to be made. Luckily you have both cars. For the most part you'll be stripping everything (and I mean every sensor and just about every bolt) in the engine bay. The 01 has an AWM motor which is VVT, small port, wide band O2 sensors, MAP sensor, internal water pump, secondary air injection, and numerous other details I can't think of since it's 1am here.