- ons 12 sep 2007, 06:04
#131765
Detta övertygade mig att det måste vara LH som va kass
Symptoms of Bad LH 2.4 ECU. See also Engine Failure/No Start: Bad ECU
Common symptoms of a failing LH injection module:
Engine will not run at idle
Air-fuel mixture is too rich (this can damage catalytic converters)
No fuel pump operation, butthefuel pump operates when its relay is jumpered between pins 30 and 87/2
The engine will not rev higher than 3000 RPM
Engine will not start, spark plugs are dry and the ignition system produces spark.
Multiple error codes, sometimes randomly generated, despite using known good sensors and components.
ECU Diagnosis. First check the fuel injection system and radio suppression relays. Check all the sensor inputs to the ECU at the connector: you can remove the small screw and wire tie on the cover, pull it off, and remove the little "haircomb" plastic piece on the side which exposes all connectors without actually disconnecting the ECU itself. All grounds, power and sensor inputs should be tested at this plug before the ECU is condemned. Is the ECU is getting a signal from the ignition system? How about power from the ignition? Only after a complete diagnosis should you condemn the ECU.
This note is from Car Electronic Service in the UK and applies to: 1988 to 1992 740 and 740 GLE with Bosch Jetronic LH 2.4 fuel injection ECUs part numbers 590/591/594/595. Symptoms...No prior warning, car usually breaks down on road or fails to start when warm through loss of fuel pump relay control. Diagnostic checklist: ACCURATELY Identify fuel pump relay and remove. Now take a small piece of wire to jumper terminals 30 and 87/2 on the relay board (the terminals are identified on the relay module pins). USE CARE. The 2 terminals are the nearest left and middle right pins on the relay board). This +12V jumper should make the car act like the fuel pump relay is ON. If car now starts and runs, take for road test to confirm OK (put on exhaust gas analyser first with catalyst equipped vehicles). IT IS NOT OK to continue to use the car with this fixed jumper feed to fuel pump. If the car runs, then the ECU fuel pump control circuit is bad.
945-91, v70-04