■RVICI KE-Jetronic Perhaps you're wondering why we've combined this pair of 'Two For One" follow up articles. It wouldn't seem that Bosch KE- Jetronic and Nissan ECCS engine management systems have a great deal in common. You might even say they are more dissimilar than they are alike. We've already spent a lot of time with both of these systems in IThe ignition signal is a very 2 Backed out wiring connector previous articles. Our coverage of KE- important KE sensor input. terminals can cause intermittent Jetronic systems began in the Detonation or poor low speed per component operation. This idle air stabilization valve worked intermit December 1988 Import Service and formance on models with knock tently. After removing the harness continued in March and July of 1989. sensor control units may be caused Even after three in-depth articles by a detonation sensor that is connector's rubber boot, we found that the center wiring terminal had on KE and two on ECCS, we found installed either too loose or too there was still more material to tight. The proper sensor installa never been properly seated in the harness connector. Peel back the cover. Both articles include vehicle tion torque is 10-12 Nm (7-9 ft-lb) for specific troubleshooting tips and Type I sensors (wiring enters sen protective wiring boots and give the repair procedures. And that's what sor off center) and 20-25 Nm (15-18 wires a light tug. Bend back loose makes them similar. ft-lb) for Type II sensors (wiring terminal locking tabs, then make A special thanks goes out to Dre connection enters from the side). sure they are locked in place. Brungardt for his technical assistance. ECCS We covered the operating theory of the Nissan ECCS engine manage ment system in the April and May 1990 issues of Import Service. Like the KE articles, there was more infor mation than we were able to include in the first two parts. We thought this would be a good time to bring you up to date on both systems. Unlike the KE system, all ECCS systems have self-diagnostic ability. IOn most ECCS systems, extra 2 The mixture heater used on We covered the use of self- air is drawn into the exhaust ECCS equipped 1988 Sentras diagnosis as a troubleshooting aid system through a passage in the air and Pulsars is not interchangeable in the second part of this series. flow meter. The air injection valve with the mixture heater used on But there are many components (AIV) uses reed valves and the 1987 models. Interchanging these in the system that aren't recognized engine's negative exhaust pulses to parts will cause a no idle-up con by ECU self-diagnostics and won't make sure the air flows only toward dition from the idle speed control set a trouble code. We've concen the exhaust. The reed valves can valve (ISCV). The 1988 mixture trated on vehicle-specific symp fail, allowing exhaust and moisture heater can be identified by an extra toms and problems that will affect to attack the inside of the air flow ISCV air passage at the rear of the ECCS operation, but probably meter. Corrosion inside the alumi heater. 1987 models do not have this won't be picked up by the ECU's num air flow meter housing or passage and will block the idle-up self-diagnostic section. other air flow meter problems are passage. usually caused by a damaged AIV. —By Karl Seyfert KE-Jetronic 3 Some KE systems are equipped 4 Disconnect the altitude sensor 5 Now jumper terminals 1 and 3 with an altitude sensor (arrow). connector. With the ignition to simulate low barometric The altitude sensor helps the ECU on, check for an 8 volt reference pressure (high sensor resistance). decide the correct milliamp current signal from the ECU at terminal 2 The DPR current should decrease to send to the differential pressure (middle terminal) of the harness to approximately 0-4 milliamps. regulator (DPR), based on baro sensor connector. Terminal 3 goes The low DPR milliamp current metric pressure. The ECU should to ground, and terminal 1 sends the leans out the fuel mixture to match decrease the DPR's milliamp signal sensor's return signal to the ECU. the thin air at high altitude. If your approximately 1 milliamp for every Disconnect the coolant temperature readings in the previous tests are additional 1000 feet of altitude sensor. Use a shunt harness to con correct, the altitude sensor may be above sea level. At sea level, the nect a DVOM to the DPR, then at fault. Reconnect the sensor's altitude sensor has no effect on the jumper terminals 1 and 2 (zero harness connector, then apply DPR reading or fuel mixture. sensor resistance) to simulate high vacuum to its vent hole. DPR cur barometric pressure. DPR current rent should drop. should increase about 3 milliamps. ECCS 3 A burned distributor cap rotor 4 A defective throttle sensor on 5 The molded ignition coils button may damage the LEDs 1986.5 Trucks, 1987 Pathfinders, used on many ECCS vehicles and photo diodes inside E16 Sentra Vans, Sentra Coupes and 4WD can crack in hard to see places. and Pulsar distributors. The stray Wagons, and 1987 Pulsar NXs can Cracks allow secondary voltage to secondary spark works its way cause an intermittent engine hesita leak to ground, especially under down the distributor shaft and tion or surge under load (it feels load. Misting the coil with water "blinds" the distributor's photo like the ignition is being shut off for while the engine is running won't diodes. Then the diodes may fail less than a second at a time). The always reveal the cracked area. Take intermittently, and cause driveabil- sensor tells the ECU the exact the coil off the car and give it a ity problems by sending incorrect throttle position. Measure the careful inspection. Cracks may be engine speed and crank angle posi sensor's resistance while slowly hidden behind the metal coil tion signals to the ECU. Always opening the throttle. Watch for mounting brackets. A chalky white check cap and rotor condition dur opens or dead spots. deposit outlining the cracked area ing maintenance work. is a dead giveaway. 6 If the engine has an unstable If the duty cycle is incorrect, 8 If the duty cycle is a steady 25 or incorrect idle speed, use the adjust it by slowly turning the percent, the idle speed is following procedure to test the idle idle screw (not the idle stop adjust incorrect. Check for vacuum leaks air stabilization system. The engine ment). If duty cycle still reads 33 to at the throttle body gaskets, seals, oil temperature must be above 80 40 percent, make sure the A/C is and all hoses in the intake system. degrees C, ignition timing must be off. Also make sure the ECU is Idle fluctuation or hunting can also set to specs, and the A/C switch getting a closed throttle switch be caused by a vacuum leak in the should be off. With the oxygen signal at ECU terminal 13. If the air shrouded injection system. sensor connected, duty cycle duty cycle still can't be adjusted to Revised air shrouded injection measured at the idle air stabiliza specs and varies between 20 and 25 parts are available to replace a tion valve's test connector should percent, check for an RPM signal distorted o-ring and a distorted or be 28 percent (±2 percent). from the ignition control unit at cracked plastic connecting flange ECU terminal 25. which may cause vacuum leaks and an unstable idle. 6 Cold engine fast idle speed on 7 A loose engine ground bolt at 8 A damaged oxygen sensor 1985-88 Maximas is not directly the front corner of the intake connector can cause an inter controlled by the ECCS control manifold on 1985-88 Maximas can mittent surge or hesitation at 1500- unit. Maximas (and several other keep the engine from idling, cause 2000 RPM on 1987-88 Sentras after ECCS systems) have separate elec it to run rough, and make the the engine is warmed up. Check the trically heated bi-metal auxiliary exhaust smell bad. Even though the routing of the oxygen sensor air regulators like those found on ECCS control unit is located under harness. The connector may be earlier L-Jetronic systems. The air the passenger seat, wire 19F at the distorted if the harness is pulled regulator's shutter wheel can stick engine grounding bolt supplies the too tight. This can cause an inter in the closed position, causing a ECU's main ground circuits. The mittent connection, especially at hesitation and no fast idle when the ECU can't accurately control the the connector's middle pin. Also engine is cold. Since the regulator system without a good ground. make sure the tight harness hasn't is outside the ECCS system, no Clean and tighten the ground con chafed any of the oxygen sensor trouble codes will be stored. nection as necessary. wiring. KE-Jetronic 9 Check the idle air stabilizer U Here's a KE tip that's worth valve's windings for continuity. pressure will cause hard repeating. Some KE systems Resistance should be 24-30 ohms starting problems. KE systems have a mini-filter built into the between the outside terminals and should maintain a minimum of 2.6 banjo bolt at the inlet side of the 12-15 ohms between either of the bar (38 PSI) residual fuel pressure fuel distributor.