1989 Mercedes Benz 420SEL Air/Fuel Mixture Adjustments

1989 Mercedes Benz 420SEL (126 Chassis) V8-4196cc 4.2L SOHC (116)

Adjusting the Air/Fuel Mixture

a. Refer to NOTES CONCERNING THE AIR/FUEL MIXTURE and CHECKING THE AIR/FUEL MIXTURE ADJUSTMENT for tester connection locations and procedures prior to adjusting the idle air/fuel mixture. Adjustment procedure will require the use of on/off ratio tester (Bosch KDJE-P 600) or equivalent.

b. Adjustments are to be performed after the engine has reached normal operating temperature.

c. All d. accessories must be switched off. Engine must be in good mechanical working order and be free from electrical misfires.

e. If after completing the adjustment procedures the correct On/Off Ratio can not be obtained refer to technical service bulletin #07318 in TECHNICAL SERVICE BULLETINS . Information concerning the possibility of internal fuel leakage within the CIS-E fuel distributor may lead to the remedy for the problem.

1. Remove the air cleaner and drill a hole approximately 6 - 8 mm (15/64-5/16 in.) deep with a 2.5 mm (3/32 in.) twist drill in each of the break away bolts on the adjustment tower. CAUTION: Do Not Drill Through The Bolts As The Metal Chips May Cause Engine Damage. Thoroughly Remove The Metal Chips With A Cleaning Rag . Download File PDF


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