Bosch LH 2.3 ECU Repair
From August 1986 (Porsche 1987 model year) with the introduction of the S4 model, all 928 models used the Bosch LH 2.3 Jetronic fuel injection ECU (sometimes called the “Brain”).
The Porsche part numbers are in a series 928.618.123.10 to 928.618.123.30. The corresponding Bosch part numbers are 0280.002.504 to 0280.002.514 respectively. These are used in the S4, CS, SE, GT and GTS models.
These ECUs have a poor reliability history. This is almost entirely due to failure of the “tile” – a Thick Film hybrid circuit exclusive to Bosch. JDSPorsche has developed a re-engineered replacement for this vital component.
A common LH ECU failure is for the fuel pump to fail to run due to the fuel pump relay not being energised by the LH ECU. Often, a regular clicking will be heard in the engine bay as soon as the ignition is switched on.
We are now able to offer re-manufactured LH ECUs to Porsche enthusiasts, at a very competitive price. Due to the large number of variants of the basic unit, it is often not possible to offer an exchange unit from stock. Your faulty unit can usually be turned around by our workshop in 2 working days.( Please see the FAQs for more information
Bosch 928 LH2.3 EZK ignition ECU Repair
From August 1986 (Porsche 1987 model year) with the introduction of the S4 model, all 928 models used the Bosch LH 2.3 Jetronic Ignition ECU. This was used in conjunction with a seperate ECU for the fuel delivery system - the LH ECU.
The Porsche part numbers are in a series 928.618.124.11 to 928.618.124.30. The corresponding Bosch part numbers are 0227.400.035 to 0227.400.197 respectively. These are used in the S4, CS, SE, GT and GTS models.
The EZK ECU takes engine speed pulses from a sensor on top of the engine bellhousing from a gearwheel below. These pulses are processsed in the EZK ECU, and the igntion timing is fully mapped according to engine rpm, throttle opening, engine temperature. The output of the EZK is used to trigger two external output stages which drive the twin igntion coils.
These ECUs are usually very reliable. However there are now a significant number of these units failing, and accordingly JDSPorsche have constructed a dedicted test jig in order to fault find and repair these units.