Only the third generation of a highly popular model with an index of 100 had the 2.3-liter Audi 2.3 NF engine installed. The engine was assembled at the company’s businesses between 1986 and 1990. This power unit was renamed AAR in 1990 following a minor upgrade.

The EA828 series includes: RT, KU, NF, NG, AAR, AAN.
Specifications
| Production years | 1986-1990 |
| Displacement, cc | 2309 |
| Fuel system | KE-III-Jetronic |
| Power output, hp | 136 |
| Torque output, Nm | 190 |
| Cylinder block | cast iron R5 |
| Block head | aluminum 10v |
| Cylinder bore, mm | 82.5 |
| Piston stroke, mm | 86.4 |
| Compression ratio | 10.0 |
| Features | SOHC |
| Hydraulic lifters | yes |
| Timing drive | belt |
| Phase regulator | no |
| Turbocharging | no |
| Recommended engine oil | 5W-40 |
| Engine oil capacity, liter | 4.5 |
| Fuel type | petrol |
| Euro standards | EURO 2 |
| Fuel consumption, L/100 km (for Audi 100 C3 1989) — city — highway — combined |
12.5 7.8 9.3 |
| Engine lifespan, km | ~340 000 |
The engine was installed on:
- Audi 100 C3 (44) in 1986 – 1990.
Disadvantages of the Audi NF engine
The majority of owners’ issues stem from KE-III-Jetronic system malfunctions.
Air leaks or a dirty idle valve are typically the causes of floating engine speeds.
Fuel pump failure and clogged nozzles are common causes of unstable operation.
Additionally, a number of the ignition system’s parts are unreliable.
Hydraulic lifters frequently break and begin to knock closer to 200,000 kilometers.
