A4 in FF

I bought an AAH engine out of a '94 90 to replace a spent AFC in a '96 A4 with low/no oil pressure and lots of extra noises. I was planning swap out everything on the long block to make it fit (intake , exhaust, etc.). As I was looking on the 12v.org website at the differences between the engines I saw that the 2 engines have different heads and therefore valve timing. Do I need to swap out the heads to get the AAH to work with my ECU? Anything else I may have missed?

A6Gary

system is installed with the AAH engine so the ECU will work. There are also differneces in the engine sensors between the AAH and AFC engines that tie into the motor management system (MMS). Your '96 AFC engine has MMS 400 or 411, while the '94 AAH engine probably used MMS 300. You can make the switch, but you'll need to do some research to ensure the newer ECU communicates with the older AAH engine.

moribundman

My '96 AFC has no secondary air injection

A6Gary

Nether does my '96 A6 Avant, which has MMS 400.

moribundman

The air pump, not the ECU (It already broke).

meaudi3

Hello....
I was wondering if any more information was dug up about the ECU - engine compatibility.
I've got a 96' A4 AFC engine in a 95' cab.
It keeps throwing EGR low flow codes and fuel rail trim stuff.
I've been through the EGR system pretty closely, but not finding the culprit.
thanks.....

A4 in FF

I've had the engine in the car for about a month with the AAH heads and have had no issue with the difference.