The D- Jetronic Electronic Control Unit (ECU)Author: Paul B. Anders. Date: 4/1. Version: 3. 1. NOTE: This is a fairly technical document that has more information. If you would just like to understand a bit. ECU works and some answers to the more common questions and. I'd suggest reading the first three sections, then moving on to the. Common Questions and Answers. The D- Jetronic Electronic Control Unit (ECU) controls most aspects of the fuel injection system. Regardless, the engineers at Bosch did. ECU accurately maintains proper mixture control for many different. The ECU would continue to remain a mystery to owners if it weren't for the efforts of Frank Kerfoot, a former Bell Labs engineer. Frank was. an SCCA racer in the 1. He took it upon himself to reverse- engineer a schematic of the ECU for analysis. Frank used a 0. 39 9. A ECU, which was used on the 1. L cars. Frank has. I've posed to him and I've. While I'm an electrical engineer, I'm pathetic at circuit analysis, so I've. EE friends to help me muddle through. If I don't understand how a circuit. ECU works, I'll say so below and hopefully will get information on it for. A review of my web page on the. D- Jetronic injection system may be helpful before proceeding on to the. ECU. Back to index. The ECU controls the timing and duration of. FPR). The operation of the cold start valve (CSV) is independently controlled by the thermo- or thermo- time. TS), not the ECU. The ECU determines the timing and duration of the injection pulses by processing signals from the. Start), trigger contacts (TC) , manifold pressure sensor (MPS), temperature sensors (TS1. TS2 - cylinder head temp), and throttle position switch (TPS w/. IS). The ECU controls the operation of the FPR by processing signals from. TC. The timing of injection pulses is determined by signals from the TC. In 4- cylinder implementations of D- Jetronic, the injectors are paired and pulsed together - this is called . Determination of the injector pulse duration (Ti) is fairly complex. Without going into fuel injection. Tb) for a specific engine load to achieve a target air/fuel ratio. In the D- Jetronic system, engine load is determined by measuring the intake manifold. MPS. Ti is also affected by specific operating conditions - . These conditions are sensed. ECU from Start, TS1 and TS2, TC, TPS, and the MPS. The ECU adds additional pulses (during acceleration) and/or modifies the value of Tb for these. Ti. The synchronized pulse of duration Ti. For over- run conditions (closed throttle and. ECU. shuts off the injection pulses when the engine speed is above a threshold level. The ECU supplies ground to the FPR to run the fuel pump under three conditions. This pressurizes the fuel. This reduces fire hazards from. A check valve in. When the key is turned. The state of Homefront: The Revolution is, quite frankly, appalling. While Kaos Studios’ original effort was mundane but competent, Dambuster’s attempted sequel. List of notable events in music that took place in the year 1970. Lastly, if the engine starts, and. ECU will keep the fuel pump running. If the engine does not. If the engine stops running (stalls) while the key is. This reduces fire. Back to index. Main and Daughter Boards (0 2. ECU)Main Board - This board has all the circuits on sheets 1 and 2 of the. D5. 02 is the large diode on the heat sink on the right. The two. germanium (AUY2. The power resistors are in the heat sink pack on the top (and are bonded. ECU case for thermal transfer). According to Bosch, this main board is. D- Jetronic applications. Note the relatively empty. On earlier ECU's (e. ECU's. A more advanced. ECU's, used on the '7. L motors. Daughter Board - This board has all of the circuits on sheet 3 of the. The 3- wire cable in the lower left is for the idle mixture. According to Bosch, circuits on the daughter board are. From the left to the right: 0. Back to index. Sheet. Timing Logic (TL), Pressure- Sensing Loop (PL), Over- Run Shutoff. OS), Injection Logic (IL), Switching Logic (SL), and Output Drivers (D1. When a general overseeing a battle in ancient Persia was approached by a scout reporting that the conflict was going badly, the commander, in a fit of rage, killed. Start the Revolution Without Me is a 1970 film directed by Bud Yorkin, starring Gene Wilder, Donald Sutherland, Hugh Griffith, Jack MacGowran, Billie Whitelaw, Orson. Yes, I am still pro Remain, and also generally pro immigration, and I am still hoping the Brits take a cue from DeAndre Jordan. 1979 Revolution: Black Friday is a choice driven, narrative game that brings players into the brooding world of a nation on the verge of collapse. D2)Sheet. 2: Acceleration Enrichment (AE), Fuel Pump Control (FPC), and Cylinder. Temperature Compensation (CTC)Sheet. Engine Speed Sensor (ES), Engine Speed Compensation (SC), Pulse. Width Multiplier (PWM), Idle Mixture Adjustment (IM), and Idle- Cold. Mixture Compensation (ICM)Back to index. A block diagram of the ECU can be. Porsche 9. 14 Factory Workshop Manual vol. While instructive, it does not accurately reflect the. ECU. The diagram below is in the same spirit. ECU schematics: Below is a short description of each ECU block: Engine. Engine speed correction (ES & EC) - The ES stage. PL. The EC stage. ES. Fuel. pump control (FPC) - Controls the FPR using inputs from Start and the ES. Pressure- sensing. PL) - Creates the basic injection pulse using inputs from the. TS1, MPS, IM, and SC. The TL supplies the injection timing signal for. Idle. mixture adjustment (IM) - Adjusts the mixture at idle using inputs. IS and IA. The IA is not present on early ECU's. Idle- cold. mixture compensation (ICM) - Adjusts the mixture for cold start, and. Start and IS. Over- run. OS) - Shuts off injection on overrun, using inputs from the. PL and IS. Not present on all ECU's. Pulse. width multiplier (PWM) - Delays and stretches the basic injection pulse. ES, FC, AE, and CTC. Cylinder. temperature compensation (CTC) - Adjusts the mixture for cylinder head. TS2 and ICM. Injection. IL) - Combines inputs from the FC, PWM, and AE to create the. Acceleration. enrichment (AE) - Provides immediate and delayed acceleration enrichment. TPS. Switching. logic (SL) - Routes the final injection pulse to the correct injector. IL and TL. Timing. TL) - Creates group injection gate pulses and injection timing. TC. Output. driver stages (D1, D2) - Converts the final injection pulse for each. I1- 4. Back to index. The TL controls which injector group is active, and signals the beginning of. PL. The two switches in the TC are de- bounced and connected to. T2. 51 and. T2. 52 that are 1. Each square wave output goes to an edge detector and the input NOR. IL). The edge detector is a differentiator circuit with a normal output of about +2 V. Pulses from both edge detectors are combined and are. PL). Each pulse is the starting. The heart of this circuit is. T2. 01 and T2. 02. The basic injection pulse appears at the collector output of T2. The negative- going pulses from the. TL edge detectors turn T2. T2. 02 on, which drives its collector. This causes a current to flow through L1 and the diode- resistor. R4. 01, R4. 02 . Since the inductances of. L1 and L2 are dependent on the MPS armature position, the induced negative voltage on L2 is dependent. MPS. document for a description of how the MPS works). As the. current through L2 decays, the induced negative voltage decays, eventually to the point. V) where T2. 01 turns back on, turning T2. The more negative the. SC and IM, the longer the hold- off period and the longer. From reading. the resistors on a scrap ECU, I found the following resistance values: R4. K ohms, R4. 03 = 5. R4. 05 = 1. 5 K ohms. Ignoring the diode drop of. D4. 01, and using the nominal value of TS1 at. F of 3. 00 ohms, I calculate that Re = 3. If TS1 is open (disconnected), then. Re = 4. 36 ohms, about a 1. If TS1 is shorted, Re = 3. Higher values of Re increase. A common mechanic's trick is to. TS1 sensor on an older motor, increasing the injection pulse. Older motors tend to have vacuum. When the. throttle is fully closed, the idle switch is activated, grounding terminal . This ground is one of. T8. 07, along with the output of a low- pass filter. PL as an input. When the engine speed. T8. 07 is. turned off, forcing T3. When the engine. speed drops below the threshold, or if the throttle is opened, T8. T3. 01 is now determined by the basic injection pulse. Below is an. incomplete list of those ECU's with and without the OS circuit: OS Circuit Present: 0 2. OS Circuit Missing: 0 2. The IL combines multiple injection signals to create the final injection. The T5. 07 NOR gate enables injection when it receives a high signal from. T3. 01 (when the basic injection pulse from the pressure sensing. AE pulse output, or from the inverted output of the PWM. The SL uses two NOR gates that each. IL as one input. The other input of each NOR gate. TL flip- flop outputs, which are square waves that are 1. Because the inputs to the NOR gates are 1. T5. 07. Each. driver uses two power transistors and load resistors to provide the proper. Accounting for the 0. V drop across D5. V when the car is running, 1. V is present. at the emitters of the final driver transistors. Therefore, when the driver. V drop across the junction, so. V through a 6 ohm load. Rload, a 5 W ceramic power resistor, bonded to the case of the ECU to. Note that this is an approximate model only, because the. The. characteristics of a solenoid are different than a simple inductor due to the. Measurements I've taken on one of my injectors show Linj. H and Rinj 2. 6. 9 ohms. When the driver transistor turns on and current begins. Due to the energy required to develop the. XL - the effective resistance of the inductor. Because XL. is initially the largest resistance in the series path of circuit elements (Rload. Rinj, and XLinj), almost all. V across it. Therefore. As the. field builds, XL decreases and less voltage is dropped across the injector - . V. It. takes about 2. Once the. magnetic field is at steady- state, the voltage drop across. I * Rinj, where I is the steady- state current. If you. use the nominal spec value of R = 2. V, you would get a sustained voltage drop across the injector of 3 V. When the car is running, the actual system. V. Accounting for the higher measured injector resistance over. V, the actual. measured sustained voltage is 4 to 5 V. Note that the calculated drive voltage corresponds exactly with. V (data courtesy of Roland Kunz). At the end of the injection period, the driver transistor turns off, which. The rapid collapse of. The mathematical expression of this. VL = Linj * d. I/dt , where d. I/dt is the time derivative of current. The net effect is that you get a large negative spike of. I have measured a peak of - 2. V, decaying. in about 1 msec to zero volts. The inductive. voltage spike (and resultant current) is limited by the series combination of.
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