Fuel System - Driveability Improvement
CATEGORYEngine
SECTION
2
PAGE
22
ISSUE
11/92-0270
CODE
240
Subject:
Driveability Improvement: CIS With Heated Oxygen Sensor
Application:
1988 900 Model (B201 Engine) Only
Supersedes 08/90-0018
A service procedure has been developed which improves the driveability of 1988 900 models (equipped with the B201 engine and Continuous Injection System) during the initial warm-up period. This service procedure entails making maximum use of the tuning specifications, installing a set of new injection valves with Viton seats, and installation of new fuel injection components.
Note
Before taking any steps to install new parts, it is imperative that the basic tuning settings of the engine are optimized to the maximum permitted tolerances. Ensure that there are no leaks in the injection system, the throttle housing is clean, the sensor plate height is adjusted properly, and that all fuel pressures are correct. If fuel pressure readings indicate a bad warm-up regulator, it should be replaced with a new one.
Parts Required:
Viton Injector (qty 4) P/N 78 56 354
Warm-up Regulator P/N 75 15 554
(P/N 02 45 159 has been discontinued)
Auxiliary Air Valve P/N 91 14 869*
Modification of existing vacuum impulse switch*
* This component/change is certified only for the 1988 900 with B201 engine.
Tune-Up Specifications
Correct tune-up specifications are essential:
^ Timing: 21~ BTDC at 2000 rpm
^ Spark Plug Gap: 0.6 mm (0.024 in.)
^ Intake Valve Clearance: 0.28 mm (0.011 in.)
^ Exhaust Valve Clearance: 0.48 mm (0.019 in.)
^ Pulse Ratio: (engine at normal operating temperature) 45%
^ Idle Speed: 875 +/- 75
Action:
If driveability problems occur with the engine tuned as specified above, the following steps should be performed:
1. Install the new auxiliary air valve (Figure 1).
2. Remove the spring from the vacuum impulse switch (Figure 2). After reinstalling the switch, test for proper function.
3. Fit the set of Viton injectors. With the engine at normal operating temperature, set idle speed to 900 rpm. Recheck the pulse ratio.
4. Install new warm-up regulator if necessary. See Note in the beginning of this bulletin.
Warranty Information:
This procedure is not covered by emissions control warranties.