CIH Engine - Bosch FI Conversion

 03.01.2002

Where do you start? What do you need?

Converting the Opel CIH engine to FI (Bosch L- or LE-Jetronic) is not quite as daunting as it would seem. In the US, salvage yards can only be used as a source for the L-Jetronic system used on 1975 Opel models. LE or Motronic systems will have to be imported. Make sure to get all the required parts for the conversion, as listed below. Some parts are near impossible to get after the fact!
  • Intake manifold and all of it's components:
        Injectors; throttle body; throttle linkage and cable; fuel fittings, hoses and regulator
  • Air flow meter, air filter housing and flow meter air hoses
  • Wiring harness with all relays (L - Dual Relay, LE Main Relay)
  • FI Controller (ECU, Computer)
  • Distributor (75 is vacuum retard only and limited to ~25 mechanical advance)
  • Thermostat housing (water temp sensor, thermo-time sensor, auxiliary air valve mounted)
  • Deceleration valve (L only)
  • Fuel pump ('75 with special power connector plug) and filter
  • 5/8 Heater Hose Nipple (near OP sender, instead of block coolant drain plug)
  • Exhaust manifold

Fuel Line Routing: Yellow lines mark pressurized fuel lines, orange marks non-pressurized line back to tank. Hoses must be high quality and designed specifically for high pressure fuel injection (indicated on hose). A new line must be installed (at least 5/16 (~8mm) diameter) from pump at tank to engine room for pressurized fuel. Original nylon line (black or clear) may be used for flow back from engine compartment to tank and must be the same size as the pressure line so there's no restriction to fuel flow returning to the tank. 

              
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  Air Filter

  Crankcase Vent Line

  Throttle Valve Body and Switch

  Air Flow Meter

  Intake Manifold Plenum

  Intake Air Hose - Air Flow Meter to Throttle Body

  Fuel Pressure Regulator

  Fuel Return Line

  Pressurized Fuel Line to Injectors (from EFP)

  Cold Start Injector

  Cold Start Injector Pressurized Fuel Line

  Vacuum Line to Fuel Pressure Regulator

  Auxiliary Air Valve Filtered Air Line (in front of Throttle Valve)

  Auxiliary Air Valve to Intake Manifold Line

  Auxiliary Air Valve (Cold Start) 

  Deceleration Valve (used only on L type) 

 

Fuel Pump Assembly - should be mounted underneath rear of car as close as possible to the fuel tank. Line from tank feeding pump should be enlarged to 1/2 (~12-13mm). Fuel filter can either be mounted close to pump (shown) or in engine compartment for easier access (recommended).

 

           

 

General Information :

Fuel pressure: 34-43 PSI (2.3-2.9 kg/cm)
Idle speed: 850-900 RPM (manual gearbox)
CO in exhaust: max 1%
Temp sensor resistance: 60-86F  (15-30C): 1.45 - 3.3Kohm
         176F  (80C): 280 - 360ohm

Engine Compartment Wiring :

           
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  Cold Start injector

  Thermo-Time switch

  Injectors

  Throttle Valve switch

  Air Flow meter

  Auxiliary Air Valve (IAC Valve on LE models with integrated EAI ignition)

  Water Temperature sensor

  Distributor (including ignition controller on LE models with integrated EAI ignition)

  Ignition coil

  Battery

  FI wiring harness

  Vehicle wiring harness

  ECU - Electronic Control Unit (Computer)

  Connection to coil trigger (negative, green wire, connection terminal 1 in wiring diagrams) 

  Common ground

  L - Dual Relay or LE - Main Relay 

 

Additional Installation requirements:

1.        As FI thermostat housings have no provision for heater hose connection, remove engine drain plug under exhaust manifold near the oil pressure sender and replace with hose connector removed from original FI engine to connect second 5/8 (16mm) hot water hose from block to heater control valve.  

2.       Original fuel pump is no longer used and may be removed. Using the original fuel pump spacer as template, fabricate and install a thick 1/4" (~6mm) metal plate to cover original pump hole in the timing chain cover.  

3.       Wiring diagram doesn't show clearly that the green wire from the control unit should be connected to the negative (points/trigger - connection terminal 1 in wiring diagrams) terminal of the ignition coil. 

 

Adjustments:

After installation, everything should now work. However, if idling is poor, mixture and idle speed can be adjusted. Check all rubber airway and vacuum hoses and connections for leaks before making any adjustments.

 

Adjust idle mixture (clockwise is richer) with a screwdriver on L or a hex key on LE (shown)

 

Adjust idle speed (clockwise is slower) with a 15mm box end wrench and screwdriver

Wiring Diagram (Bosch L-Jetronic):

 

  

Pin Outs - Dual Relay:

                  

Wiring Diagram (LE-Jetronic):

1.   ECU plug strip

8.  Thermo-time switch

2.   Ground

9.  Cold Start injector

3.   Temperature sensor

10. Injectors

4.   Ground

11. Battery

5.   Auxiliary Air valve

12. Control relay

6.   Throttle valve switch

13. Fuel pump fuse

7.   Air Flow meter

14. Fuel pump

     

 

   Pin Outs - Main Control Relay :

Wiring Diagram (LE-Jetronic with IAC):

 

             Pin Outs - Main Control Relay :