Here you will find information for various conversions and modifications

Replacement of the fuel pump

The old version with the three hose connections is no longer available. However, a K-Jetronic or LH-Jetronic pump can be used for this purpose. These pumps even have a higher flow rate.

Connect the flow input from the tank to the pump. From the pump the supply line goes to the motor. The return flow is connected directly to the tank.

The then superfluous third supply line to the tank can be closed with a plug on the tank.

When replacing rubber fuel lines, always use the modern three-layer ethanol-resistant hoses. The old hoses with fabric covering must not be used at pressures of over 2 bar.

Pay attention to the condition of the cables. If the insulation begins to crumble, the wiring harness must be replaced. New wiring harnesses are available from Buttkereit.

Also important is the ground connection next to the battery, which often starts to corrode due to battery acid. Make all connections properly metallically bright and grease them against corrosion.


The D-Jetronic can also be upgraded to higher performance with the usual tuning methods. But keep your fingers absolutely off the camshaft, use only the standard shaft (D on the B20 or C on the B30). The injection program is adjusted to the input vacuum of the camshaft, if a sharper shaft is used, the values are no longer correct. In this case the injection system can go out of alignment.

Upgrading from B20F to B20E or B30F to B30E is possible without any problems, the compression only has to be increased by grinding or changing the cylinder head and the head gasket. The pressure sensor and distributor for the “E-version” must also be attached for this purpose.

  • Pressure Sensor B20 E: 015
  • Pressure Sensor B20 F: 035

It is very important to install 225 spark plugs. With the F spark plugs on the E-version there is a risk of engine damage due to sparke burners.

Modification of intake channels and valve machining is possible.

The application of a fan manifold or less resistance in the exhaust system can create negative changes, this must be tried out.

It is also recommended, to run lightly tuned engines with a slightly higher system pressure (2.2 to 2.3 bar). This results in better internal motor cooling through a richer mixture.

The use of an engine oil cooler (either the “Tellermine” under the oil filter, or air oil cooler) is a MUST for all injection engines with D-Jetronic. The air oil cooler is best version, because of better cooling performance.

Installation of Thermal Timer Switch (TTS)

Parts such as Thermal Timer Switch, intermediate piece on thread motor block, cables and plugs and the electrical wiring must be adapted.

Possibly a new wiring harness for Thermal Timer Switche made by Buttkereit is available.

Triggering of the cold start valve via the TZS +12V from the solenoid switch at the starter (connection pin 50). Ground for cold start valve from intake manifold or at pump relay.

Relay of the cold start valve is no longer necessary.

Installation of an Electronic Ignition Distributor

A new ignition distributor can be replaced by 123ignition with electronic trigger release in case the original distributor is defective.