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--- articles:cis-e_fuel_adjustment [2021/04/05 07:56] – [Reading the on/off ratio] john5788
+++ articles:cis-e_fuel_adjustment [2021/12/04 03:51] (current) – [Adjusting EHA Valve] john5788
@@ Line 34: / Line 34: @@
 At this point, the control unit should be in the diagnostic mode for outputting the fuel trim as an on/off ratio. After this, when the engine is started, the CHECK ENGINE LIGHT should be illuminated.
-==== Notes and Exceptions ====
+**Note:** Some ECUs do not require being put into a diagnostic mode and will begin outputting a duty cycle reading after 30 seconds of idle time after the engine has been started.
-  * 1993 190E 2.6 - This ECU does not need to be switched into a special mode. The on/off ratio will be available after the engine has been running for 30 seconds.
 ===== Reading the on/off ratio =====
@@ Line 61: / Line 59: @@
 ===== Performing Adjustments =====
+The adjustment procedure can be generalized as follows:
+  - Engine is at operating temperature, 80C
+  - Record average duty cycle at engine idle
+  - Record average duty cycle at engine speed of 2500 RPM
+  - Adjust EHA valve and adjustment screw on fuel distributor until duty cycle for engine speeds at idle and 2500 RPM are near 50% and within 10% of each other
+==== Adjusting EHA Valve ====
+<grid>
+<col sm="6">
+  - Remove EHA valve from fuel distributor
+    - Unplug wire connector
+    - Remove 2 screws holding EHA valve to fuel distributor while covering the EHA valve with a rag to catch fuel that will squirt at your face
+    - Pull EHA valve off fuel distributor, noting the 2 green rubber sealing rings.
+  - Remove the screw cover with a flathead screw driver
+  - Use a 2mm allen key to turn the adjustment screw inside the EHA valve with small adjustments (1/4 turn at a time)
+    - Turn clockwise to **enrichen the fuel mixture**. This **decreases the duty cycle** or **increases the voltage**, depending on whatever method you are using.
+    - Turn counter-clockwise to **lean the fuel mixture**. This **increases the duty cycle** or **decreases the voltage**, depending on whatever method you are using.
+  - Reinstall EHA valve
+</col>
+<col sm="6">
+<grid>
+<col sm="6">
+<thumbnail>
+{{ articles:eha_valve_screws.png?300 }}
+<caption>EHA valve screws</caption>
+</thumbnail>
+</col>
+<col sm="6">
+<thumbnail>
+{{ articles:eha_valve_seals.png?300 }}
+<caption>EHA valve seals</caption>
+</thumbnail>
+</col>
+<col sm="6">
+<thumbnail>
+{{ articles:eha_valve_backside.jpg?300 }}
+<caption>EHA valve screw cover</caption>
+</thumbnail>
+</col>
+</grid>
+</col>
+</grid>
+==== Adjusting Fuel Distributor Screw ====
+If there is a steel plug  present, it needs to be drilled out first. Engine must be idling for this adjustment.
+<grid>
+<col sm="6">
+  - Insert 3mm allen key or screwdriver into the adjustment tower.
+  - Push down against spring until the screw fully contacts the mixture setting screw. Pushing further past this point will cause engine to stall.
+  - Turn clockwise to enrichen the fuel mixture. This **decreases the duty cycle** or **increases the voltage**, depending on whatever method you are using.
+  - Turn counter-clockwise to lean the fuel mixture. This **increases the duty cycle** or **decreases the voltage**, depending on whatever method you are using.
+  - Use small increments for adjustments such as 1/4 of a turn while checking the new duty cycle or voltage to avoid making large changes that could cause the engine to stall or not start.
+</col>
+<col sm="6">
+<thumbnail>
+{{ articles:cisadjustmenttower.png?600 }}
+<caption>CIS Adjustment Device</caption>
+</thumbnail>
+</col>
+</grid>