奔驰W166OM642柴油发动机概述.pdf

2014 9 上海志华汽车科技有限公司hTTP 1 Diesel engine OM642 learning objectives 02 04 2007 As the result of the diagnostic technician further training on the OM642 diesel engine the participant can General learning objectives use the general and changed diagnosis routines differentiate a customer complaint from a system function by using the complaint analysis Specific learning objectives independently conduct a complaint analysis and work through it using DAS HMS 990 WIS and TIPS select and confidently apply the individual diagnosis routines suitable for the situation Training material Vehicle with OM642 engine Diagnostic aids DAS HMS 990 WIS TIPS Method Practical situational tasks on the OM642 engine 104 2014 9 上海志华汽车科技有限公司hTTP 2 After working through this chapter on the OM642 engine the participant can Rough objectives point out the system design of the OM642 engine point out the system functions of the OM642 engine describe the special features of the OM642 relevant to service and customers Specific learning objectives describe the system design of the OM642 engine describe the system function of the OM642 engine describe the special features of the OM642 engine relevant to service and customers Training material Vehicle with the OM642 engine Cut away model Method Theory presentation group discussion Practical situational tasks on the OM642 gasoline engine Important Information for Service The menu items in DAS have been adapted appropriately to the technical state of the vehicle and development of the OM642 engine These menus will be worked on during the customer specific situational tasks All points that are relevant for diagnosis will be handled in the form of information or practical exercises Any possible modifications or deviations will be discussed in connection with the further training measure 105 2014 9 上海志华汽车科技有限公司hTTP 3 02 04 2007 106 FG 00 10 Technical details in comparison Transmission Cylinder number Bank angle Valves cylinder Displacement Bore Stroke Cylinder spacing Compression Rated output at rpm Rated torque at rpm Engine weight Unit cm3 mm mm mm 6 kW at rpm Nm at rpm kg OM642 3 0l V6 diesel 7 gear automatic V6 72 4 2987 83 92 106 18 165 at 3800 510 at 1600 2800 208 Manual transmission OM642 3 0l V6 diesel V6 72 4 2987 83 92 106 18 165 at 3800 415 at 1400 3800 220 2014 9 上海志华汽车科技有限公司hTTP 4 FG 01 30 气缸盖 气缸盖由高强度铝合金制造 每侧双凸轮轴和 4 气门技术 由于气缸燃烧峰值压力达到 175bar 和规定的高性能输出 气缸盖需要耐高温和高机械负载 凸轮轴轴承集成于气缸盖和气门室盖上 AR01 30 P 5800TI P01 30 2262 00 图例 1排气门 2进气门 3喷油嘴孔 维修提示由于凸轮轴轴承配对性 当更换损坏的气门室盖时 整个气缸盖必须一起更换 107 2014 9 上海志华汽车科技有限公司hTTP 5 FG01 40 曲轴箱 气缸角度是72度 气缸间隙为106mm 曲轴箱重量为41kg 曲轴箱由高强度铝制造 气缸套由灰铸铁制造 曲轴由四个主轴承安装固定 AR01 40 P 8000TI AR01 40 P 8913TI 图例 1曲轴箱 2气缸套 3机油尺导管 维修提示 油底壳密封垫被液态密封 2014 9 上海志华汽车科技有限公司hTTP 6 P18 40 2192 00 FG01 45 油底壳和机油测量 AR01 45 P 7500TI AR01 45 P 7555TI 机油温度传感器B1和机油油位开关S43取代了先前的机油传感器 CDI 控制单元与发动机负载数据接合计算增加型保养数据 图例 1机油油位开关S43 2机油温度传感器 B1 OM642 发动机通过一个机油尺测量机油 2014 9 上海志华汽车科技有限公司hTTP 7 机油油位开关S43安装在油底壳内 机油油位开关插头位于发动机左侧 当油底壳内的机油处于最低状态时 机油油位开 关报警 簧片触点 通过磁铁控制簧片触点 一旦磁铁远离簧片 触 点打开 图例 1符子 2簧片触点 3环形磁铁 4接地触点 5基座 6壳体 2014 9 上海志华汽车科技有限公司hTTP 8 FG05 10 正时驱动 P05 10 2263 111 正时链条 凸轮轴由免维护双滚子链驱动 链条由张紧器和导轨 支撑 链轮被橡胶化 气缸左侧的排气凸轮轴和气缸右侧的进气凸轮轴由 正时链条直接驱动 平衡轴由正时链条直接驱动 高压油泵由左侧进气凸轮轴链轮驱动 以下元件由正时链条驱动 右侧气缸 进气凸轮轴 平衡轴 左侧气缸 排气凸轮轴 高压油泵 间接驱动 图例 1排气凸轮轴 2进气凸轮轴 2014 9 上海志华汽车科技有限公司hTTP 9 FG07 00 CDI系统一般概述 P07 16 2057 79 第一代 CDI 第一代CDI从1998年开始用于OM611 和OM668型 发动机上 最大系统油压为1350bar 在改进过程中 电子切断阀被取消 车型展示 168 B4 6油轨压力传感器 Y74压力调节阀 Y75喷油嘴 13低压燃油泵 19高压油泵 70柴油滤芯 71柴油预热阀 80燃油箱 A从燃油泵来的燃油压力 C回流燃油 D高压燃油 F燃油真空压力 2014 9 上海志华汽车科技有限公司hTTP 10 P07 16 2194 79 CDI 2 CDI 2系统1999年发布 与CDI 1相 比 在燃油系统 上没有改进 而是在涡轮增压的设计 有有所改进 611发动机 CDI 1 CDI 2 和612 613发动机 CDI 2 配备相同的可变涡轮增压系 统 VTG 电子切断阀从2001年04月被取消 燃油系统压力最大为 1350bar 展示车型 OM611 B4 6燃油压力传感器 Y74压力调节阀 Y75电子切断阀 截止 01年03月 Y76喷油嘴 13低压燃油泵 14燃油冷却器 19高压油泵 60燃油预热系统 70燃油滤芯 80燃油箱 A从燃油泵来的燃油压力 C燃油回流 D高压油泵 F燃油真空压力 2014 9 上海志华汽车科技有限公司hTTP 11 P47 00 2060 79 维修提示 CDI 3 CDI 3系统从2002年首次安装在奔驰车上 装配CDI 3的46 647和648发动机逐渐取代了 装配CDI 2的611 612和613发动机 燃油系统装配电子燃油泵 油量控制阀 供油 和油压控制阀 回油 依 靠 不同工况控制高压油 依靠负载工况 仅需要的燃油流入到油轨中 一些元件如机械燃油泵 燃油预热系统和燃油 冷却阀被取消 防止柴油过热 一个柴油温度传感器安装到高 压 油泵上 必要时通过油量控制阀控制流入油轨的燃油 防止燃油加热过快 油箱保护 最大燃油系统压力为1600bar OM640 发动机 A 级车 CDI 系统使用 CDI 3 代技术 展示车型 OM646 211 车型 B4 6油压传感器 B50油温传感器 M3低压燃油泵 Y74油压调节阀 Y76喷油嘴 Y94油量控制阀 19高压 油泵 21油轨 70燃油滤芯 80油箱 A从低压燃油泵来的油压 B高压油 C燃油回流 CDI 3系统喷油嘴可识别 6 位编码 使用 IMA 编码区分 2014 9 上海志华汽车科技有限公司hTTP 12 CDI 4 P07 16 2797 50 CDI 4系统从2005年安装至OM642发动机 特别是以下元件经过重新设计 油轨 压电喷油嘴 高压油泵驱动元件 电子发动机控制 通过以上改进可实现最小燃油消耗和燃烧噪声 碳微粒过滤器 PDF 在德语系区域被安装在CDI 4 系统上 带与不带碳微粒过滤器 排放都可以达到欧四标 准 最大燃油系统压力 1600bar CDI 4系统一个新特点是除了双预喷油 外还有第二次 双后喷油 带 DPF 在再生阶段 展示车型 OM642 164 车型 B4 6油轨压力传感器 B50燃油温度传感器 M3低压燃油泵 Y74油压调节阀 Y76喷油嘴 Y94油量控制阀 19高压油泵 21油轨 70燃油滤芯 80燃油箱 2014 9 上海志华汽车科技有限公司hTTP 13 下一代 CDI 系统 基于先前 CDI 4 系统研发了第五代 CDI 5 系统 配备于 C30 AMG 和 A 级车 OM640 发动机 展示车型 OM649 211 车型 B4 6油轨压力传感器 B50燃油温度传感器 M3低压燃油泵 Y74油压调节阀 Y76喷油嘴 Y76y1 第一缸喷油嘴 Y94油量控制阀 19高压油泵 21左侧油轨 22右侧油轨 23高压油管 70燃油滤芯 75燃油箱 80 5漩涡杯 2014 9 上海志华汽车科技有限公司hTTP 14 117 FG07 00 CDI系统比较一览 2014 9 上海志华汽车科技有限公司hTTP 15 燃油共轨系统优点 一般性概述 优点如下 可变燃油喷射时间 可变燃油喷射压力 精细的燃油雾化有以下优点 更好的燃烧 排放更低 更高燃烧压力 更好的扭矩和动力 更少燃油消耗 在所有工况下精确的分级计量喷油进一步提供 以下优点 更少的燃油消耗 弹性喷油压力 更高的热效率 燃烧过程更柔和 通过引燃喷射 即预喷 射 废气的再处理成为可能 通过延迟喷射 即后喷射 CDI 4 改进 CDI 4的主要改进 带选择性喷射时间的最新一代发动机控制系统 改进型高压油泵 齿轮驱动 最大喷油压力为 1600bar 改用压力晶体式喷油嘴缸内喷射 以最低的漂移量 和稳定的小计量 最多五次精确的喷射 带七位喷油量补偿码的喷油嘴 喷油量补偿 带八个喷孔的液压优化喷柱 双引燃喷射 预喷射 可控的载荷特性 减少 燃烧噪音 双延迟喷射 后喷射 带 PDF SE 碳微粒 滤清器再生 2014 9 上海志华汽车科技有限公司hTTP 16 FG07 02 高压油泵 02 04 2007 GF07 02 P 3010P GF07 03 P 5001P Repair tip 119 高压油泵运输最大1600bar的燃油至高压系统中 一个动态平衡块安装在高压油泵驱动轮 19 1 上补偿由其上的偏心轮引起的不规则运 转 燃油由低压燃油泵运输并经过燃油温度传感器 B50 油量控制阀 Y94 和油压释放阀 至高压油泵内的三个泵油元件 油量控制阀 Y94 控制流入的燃油油量 当油量控制阀关闭时 超速运转模式 一个零运送节流口传送燃油至泵油元件进行润 滑 油压释放阀限制油量控制阀处的油压约为4bar 如果油压超过4bar 油压释放阀打开并传输多余的燃油回燃油箱 另外 油压释放阀传输一部分燃油用于润滑偏心轴 任何从低压油一起过来的空气都通过油压释放阀流入高压油泵回流管至燃油箱 19高压油泵 19 1 高压油泵驱动轮 19 2 从燃油滤芯来的燃油供给 19 3 至油轨的高压燃油 19 4 回流至燃油箱的多余燃油 B50燃油温度传感器 Y94油时控制阀 当更换高压油泵时 驱动轮19 1不需要更换 在更换时可通过专用工具拉出并安装至新高压油泵上 在安装时 高压油泵驱动轮不需要对任何记号 2014 9 上海志华汽车科技有限公司hTTP 17 FG 07 03 油轨 P07 03 2163 00 GF07 03 P 6110P 维修提示 120 油轨由单独元件焊接而成 油压控制阀 油轨左侧 和油压传感器 油轨右侧 安 装在油轨上油轨储存高压燃油 对所有喷油嘴 起到一 个燃油储存器的作用 储存的高压燃油可补偿高压油泵泵油的压力波动和喷油 时的压力减少 两个油轨上一共有8个节流孔 0 8mm 节流孔用来补 偿压力波动 仅左侧油轨至右侧油轨的供油端没有节流孔 图例 21油轨 21 1从高压油泵来的高压油管 21 2连接至喷油嘴的高压油接口 B4 9油压传感器 Y74油量控制阀 如果有关于发动机运转投诉 油轨上的节流孔堵塞可作为一个潜在的故障点 左侧油轨必须与油压控制阀一起更换 2014 9 上海志华汽车科技有限公司hTTP 18 P07 16 2758 76 121 FG 07 03 喷油嘴 CDI 4 喷油嘴在设计 连接和动作上与带电磁阀的喷 油嘴显著不同 喷射时间 喷油期和相应的喷油量由以下因素定 压电晶体的动作反应时间 针阀打开 关闭速度 针阀升起高度 8孔针阀模块几何形状 油轨上的燃油压力 CDI 4 喷油嘴最显著的区分是其采用压电晶体技术 60 1促动器模块 60 4耦合器模块 60 7阀门组 60 10 针阀模块 60 13回流 60 14连接器插座 60 15高压油管连接 Y76喷油嘴 一个为拉拔器设计的匹配器可拧在喷油嘴头部螺纹处 用于拆除喷油嘴 2014 9 上海志华汽车科技有限公司hTTP 19 FG 07 04 温度传感器 02 04 2007 GF07 04 P 6110T GF07 04 P 6111T 122 三元催化转换器上游的温度传感器确定当前其上游的废 气温度 碳微粒滤清器 DPF 上游的温度传感器确定三元催化转换 器下游的废气温度 两个温度传感器是NTC型传感器 把相应的电压信号传 送至CDI控制单元 CDI 监测在碳微粒再生阶段时或之前的废气温度 TWC上游的温度传感器 B19 7 PDF 上游的温度传感器 B19 9 2014 9 上海志华汽车科技有限公司hTTP 20 GF07 04 P 6121T 维修提示 123 FG 07 04 DPF压差传感器 DPF 压差传感器记录碳微粒滤清器上 下游的废气压差 碳微粒滤清器下 下游的压力差作用在压差传感器内的压电元 件上产生一个相应的电压 并通过集成的硅芯片放大后传送至 CDI 控制单元 图例 1DPF上游废气管路连接 2DPF下游废气管路连接 3电子插头连接 带 PDF 车辆的保养范围 压差传感器及相应的管路计划每 8 年更换一次 2014 9 上海志华汽车科技有限公司hTTP 21 FG 07 04 废气背压传感器 GF07 04 P 6130P 124 图例 A传感器接头 B膜片 1针脚 1 信号电压 2针脚2 传感器电压 5V 3针脚 3 传感器接地 废气背压传感器 B60 确定涡轮增压器上游的 废气背压 CDI使用这个信号完成以下任务 监测DPF加注水平 保护涡轮增压器 保护发动机 废气背压挤压传感器内的膜片 膜片连接至电 位计上 因此电位计的电阻相应的改变 并影响信号电 压 2014 9 上海志华汽车科技有限公司hTTP 22 FG 07 05 油压控制阀 02 04 2007 维修提示 GF07 05 P 6020P 125 油压控制阀 Y74 安装在油轨上 CDI 控制单元通过 PWM 信号动作油 压控制阀 油压控制阀至油轨使用唇型密封圈 至低压回流端使用 O 型密封圈 油压控制阀不通电时 残压 60 至 80bar 可保持短暂时间 油轨压力可通过油压控制阀或油压控制阀控制 与 CDI 3 系统相比 油 压调节稍微复杂些 油压控制阀不能单独更换 当重新装配油压控制阀时 唇型密封圈 不能正确密封 2014 9 上海志华汽车科技有限公司hTTP 23 FG 07 05 油量控制阀 GF07 05 P 6010P 维修提示 126 油量控制阀 Y94 与油压控制阀一起控制燃油压力 高压控制回路 油量控制阀通过PWM信号根据需要控制流入高压油泵的油量 与不受控的高压油泵相比 在回流管路中的油温会因此减小 通过减少被压缩的油量 高压油泵的动力损耗也因此减小 高压油通过油压控制阀或油量控制阀或共同调节控制 柴油控制满足以下操作条件 一 发动机启动后60S内油压控制阀 Y74 调节油轨压力 二 柴油温度 20度时 油压控制阀 Y74 调节至油量控制阀 Y94 调节或双阀调节 Y94 Y74 转换 三 柴油温度70度时 双阀调节 Y74 Y94 至油量控制阀 Y94 转换 五 柴油温度 20 C Restrictors for pressure wave compensation are integrated in the rail For better fuel distribution the rails are connected to the fuel supply and fuel return via separate fuel ines Exercise 7The fuel injector determines the injection exclusively via the height of the needle lift 166 2014 9 上海志华汽车科技有限公司hTTP 64 Exercise 8 Exercise 9 Injectors using 6 hole nozzles are used Friction loss occurring when the injectors open and close produces a shorter actuation time in the ourse of the period of operation Exercise 10 Exercise 11 Exercise 12 Exercise 13 Exercise 14 The CDI 4 system conveys the fuel to the high pressure pump via an electric fuel pump The mechanical fuel feed pump regulates the fuel quantity via an electrical feed valve The engine has an oil level check switch for detecting the maximum oil level The fuel temperature sensor does not belong to the high pressure circuit The exhaust gas temperature increase is attained through a boost pressure increase 167 2014 9 上海志华汽车科技有限公司hTTP 65 Exercise 15 Exercise 16 Exercise 17 Exercise 18 Exercise 19 Exercise 20 Exercise 21 The high pressure pump is directly driven by the double roller chain The standard diesel particulate filter installed in the CDI 4 system is the ECE version The Euro 4 emissions standard is fulfilled only with the diesel particulate filter The throttle valve actuator is actuated via a bit synchronous interface The throttle valve actuator is actuated via a pulse width modulated signal The quantity control valve operates as of a fuel quantity greater than 15 mm The CDI 4 system operates with a dual preinjection 168 2014 9 上海志华汽车科技有限公司hTTP 66 Exercise 22 Exercise 23 The input signal boost pressure is required for pressure control dependent on the performance map oost The input signal charge air temperature is required for pressure control dependent on the performance map boost Exercise 24 Exercise 25 The input signal air mass is required for pressure control dependent on the performance map boost When the diesel particulate filter is installed the CDI 4 system executes dual preinjection only during he purging phase Exercise 26 Exercise 27 Exercise 28 At high engine speeds the flow area is increased by the VTG turbocharger and the turbine speed ops The match up between the crankshaft and camshaft signals is checked at the ignition bottom dead enter of the first cylinder Flow through the exhaust gas recirculation cooler occurs only at loads as of an engine speed of 1200 rpm 169 2014 9 上海志华汽车科技有限公司hTTP 67 Exercise 29 Exercise 30 The charge intake ports are opened in stages depending on the suctioned air mass The exhaust temperature required for regeneration of the diesel particulate filter can be attained through the load spectrum or through an additional postinjection of fuel Exercise 31 Exercise 32 Exercise 33 Exercise 34 Exercise 35 If the charge condition is greater than 70 the diesel particulate filter must always be replaced The CDI 4 system operates with a variable injection pressure of 1600 1800 bar The piezo injectors belong to the low pressure circuit The high pressure circuit regulates and stores the required fuel for injection The CDI control unit monitors the fill level of the diesel particulate filter via the exhaust back pressure ensor 170 2014 9 上海志华汽车科技有限公司hTTP 68 Exercise 36 Exercise 37 The signal representation of the crankshaft Hall sensor is sinusoidal A defective seal ring at the quantity control valve affects the control of the fuel delivery to the high pressure pump Exercise 38 Exercise 39 The system pressure regulator integrated in the fuel filter keeps the fuel feed to the high pressure pump constant at 3 5 bar The exhaust gas temperature increase is attained through regeneration glowing in the diesel particulate filter Exercise 40 Exercise 41 Exercise 42 The intake camshaft in the right cylinder head is driven directly by the double roller chain The tank protection feature is controlled by the quantity control valve The injectors are classified by an injector quantity compensation IMA code 8 character 171 2014 9 上海志华汽车科技有限公司hTTP 69 Exercise 43 Exercise 44 Exercise 45 The input signal exhaust oxygen content is required for pressure control dependent on the performance map boost A visual inspection of the basic positions of the camshafts is not necessary when the signal representations for the synchronization match up The functioning of the diesel particulate filter is monitored in the exhaust gas system by means of a charge air pressure sensor Exercise 46 Exercise 47 Exercise 48 Exercise 49 The engine has an oil sensor in the oil pan The engine has an oil dipstick for the oil level check The pressure valve and the rail pressure sensor are mounted on the rail The fuel pressure relief valve in the high pressure pump limits the fuel pressure to the volume regulator valve to approx 6 5 bar 172 2014 9 上海志华汽车科技有限公司hTTP 70 Exercise 50 Exercise 51 The quantity control valve in the high pressure pump controls the shut off process of the engine The pressure differential sensor records the exhaust back pressure downstream from the diesel particulate filter Exercise 52 Exercise 53 The quantity mean value adaptation must be reset when the turbocharger is replaced Stopping of the engine under load due to insufficient fuel pressure can be caused by a defective high ressure pump Exercise 54 Exercise 55 The exhaust gas temperature increase is attained by closing the exhaust bypass flap Internal leakage of the high pressure pumps can be clearly detected only by means of the high pressure tester Exercise 56The exhaust gas recirculation function circuit is supported by the throttle valve actuator 173 2014 9 上海志华汽车科技有限公司hTTP 71 Exercise 57 Exercise 58 Exercise 59 Exercise 60 Exercise 61 The camshaft adjustment of the intake camshafts takes place in three fixed steps The signal of the hot film mass air flow sensor is required by the CDI control unit for switching off the exhaust port Exercise 62 Exercise 63 The high pressure pump supplies the fuel to the right rail in a quantity controlled way The dual post injection for noise reduction is activated by the engine control unit as of 20 C coolant temperature 174 The fuel injector nozzle configuration has an 8 hole nozzle module The onboard diagnosis monitors the functioning of the diesel particulate filter The CDI 4 system operates with ceramic piezo injectors 2014 9 上海志华汽车科技有限公司hTTP 72 Exercise 64 Exercise 65 The signals of both the camshaft sensor and crankshaft Hall sensors are required for the temporally correct actuation of the injectors during the starting process Exercise 66 Exercise 67 The engine has a crankshaft position sensor The CDI control unit monitors the exhaust turbocharger protection with a pulse width modulated signal via the exhaust back pressure sensor Exercise 68 Exercise 69 Exercise 70 The exhaust back pressure upstream from the turbocharger is monitored via the exhaust back pressure sensor The cooled exhaust is mixed with the suctioned fresh air downstream from the throttle valve actuator to reduce the NOx value The exhaust gas recirculation operates only in neutral 175 In the deceleration mode the CDI control unit feeds a variable amount of fuel adapted to the engine speed 2014 9 上海志华汽车科技有限公司hTTP 73 Exercise 71 Exercise 72 The centrally located hot film mass air flow sensor records the suctioned air mass as well as with the integrated temperature sensor the intake air temperature The signal of the hot film mass air flow sensor is required by the CDI control unit for the quantity adaptation Exercise 73 Exercise 74 The injection period is controlled at the fuel injector via a solenoid The input signal fuel temperature is required for pressure control dependent on the performance map boost Exercise 75 Exercise 76 Exercise 77 The high pressure pump may be replaced only in combination with the drive wheel A dynamic balancer located at the high pressure pump drive makes the engine run more smoothly The exhaust gas recirculation is actuated in the full load range by the engine control unit 176 2014 9 上海志华汽车科技有限公司hTTP 74 Exercise 78 Exercise 79 The engine has a charge air cooler with water cooling The intake air is mixed with the recirculated exhaust via the exhaust gas recirculation connection with mixing throttle Exercise 80 Exercise 81 Exercise 82 Exercise 83 Exercise 84 The throttle valve actuator is actuated proportionally to the suctioned air volume with addition of the exhaust gas recirculation volume The functioning of the diesel particulate filter is monitored in the exhaust gas system by means of a pressure differential sensor The functioning of the diesel particulate filter is monitored in the exhaust gas system by means of an exhaust gas temperature sensor The functioning of the diesel particulate filter is monitored in the exhaust gas system by means of an exhaust back pressure sensor The functioning of the diesel particulate filter is monitored in the exhaust gas system by means of a rail pressure sensor 177 2014 9 上海志华汽车科技有限公司hTTP 75 Exercise 85 Exercise 86 Exercise 87 Exercise 88 Exercise 89 The increment wheel is no longer needed for the synchronization The CDI 4 system operates with an uncontrolled high pressure pump The exhaust gas recirculation increases the exhaust gas temperature in the exhaust flow The CDI 4 system operates with a high pressure of 1600 bar The quantity control valve combines with the pressure control valve to regulate the rail pressure in the high pressure control circuit Exercise 90 Exercise 91 The quantity control valve begins regulating the required fuel quantity immediately after engine start For optimal control of the charge intake ports the CDI control unit requires the pressures of the fuel feed and the recirculation quantity 178 2014 9 上海志华汽车科技有限公司hTTP 76 Exercise 92 Exercise 93 The camshaft basic position can be checked only if the cylinder head covers are removed The time delay between actuation and injection start of the injectors is measured by zero volume calibration Exercise 94 Exercise 95 Exercise 96 The intake port shutoff depends o