DME engine management and knock control
What the DME and KLR do on the 944, how they relate and which faults are typical.
In short: The Bosch Motronic (DME) controls injection and ignition. On the Turbo it works with the knock regulator (KLR), which also limits boost. Both are powered via the DME relay.
Interaction on the Turbo
The DME is linked to the KLR; either unit can cause wrong boost behaviour. The KLR receives signals directly and via the DME and drives the boost control’s cycling valve.
Chips
A 24-pin chip is given for 1986–1987 and a 28-pin chip with the same map from 1988 (table). Performance chips change the engine’s behaviour; changes to the map are outside our knowledge base.
Naturally aspirated cars
The 944’s Motronic was revised for the 1987 model year.
Typical faults
- Starting problems or stalling when hot: often the DME relay (separate article).
- Boost only about 1.2 bar: often sensor connectors such as the throttle switch or airflow meter, or a corroded connection at the cycling valve.
Technical values
Only work with the workshop manual and the correct tools. Do not use unverified values without checking them – wrong tension values can destroy the engine.
Sources
- Secondary source 944 Turbo (951) FAQ
Secondary source on the Turbo: charger, boost, wastegate, model years. Some figures quoted from the workshop manual, unverified here.
- Secondary source DME (Fuel Pump) Relay Technical Information and Testing
Function, failure pattern and testing of the DME relay.
- Secondary source Porsche 944 (Abschnitt «Production»)
Secondary source. Production tables per model year, no book citation; totals are partly inconsistent.