B200E/B230E adjustments — fuel mixture, ignition timing, idle speed

Volvo 700-series E-engines use mechanical fuel injection, the adjustments of which significantly affect engine sound, fuel consumption, and emissions.

The throttle switch (microswitch) is located on the side of the throttle body, near the throttle lever ("gas roll"). Function: The switch should click as soon as the throttle is opened slightly, and again when the throttle returns to idle. Adjustment: If the switch does not click, idle information does not reach the ignition control, which can cause uneven running.

Setting ignition timing by ear alone is risky, as too-early ignition can cause engine damage (knock/ping). Rule of thumb: Ignition timing is adjusted by rotating the distributor. Counterclockwise (left): Ignition advances (RPM generally rises, but knock risk increases). Clockwise (right): Ignition retards (engine may "putter" or run rough). Correct method: Use a timing light and adjust ignition timing according to the crankshaft pulley marks (typically around 12° BTDC at idle; check the engine-specific value on the engine bay label).

In K-Jetronic, the fuel mixture adjustment screw (CO adjustment) is not in the intake manifold, but in the fuel distributor (that large device from which steel braided fuel lines run to the injectors). Location: Between the fuel distributor and the intake port is a small hole, at the bottom of which is a 3 mm hex socket screw. Adjustment: * Clockwise: Mixture richens (more fuel). Counterclockwise: Mixture leans. Warning: The adjustment is very sensitive (1/8 turn already has a big effect). Preferably adjust the mixture with an exhaust gas analyzer. Never press the screw downward while the engine is running, as you will damage the fuel distributor.

Idle speed is adjusted from a large black plastic screw located under the intake manifold (bypass screw). Opening the screw (counterclockwise) increases RPM. Tightening the screw (clockwise) decreases RPM. Make sure before adjusting that the engine is warm and the throttle linkage is not binding.