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ecuinputdata [2008/02/11 13:59]
dmertz
ecuinputdata [2024/03/15 11:16] (current)
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 ====== ECU Input Impedance Mismatch ====== ====== ECU Input Impedance Mismatch ======
  
-There are a number of analog inputs available on the 1G and 2G ECU.  Many are used for critical engine operation, but some are available for datalogging [[ExternalSensorList|aftermarket sensors]]. ​ The problem is that some of these inputs are incompatible with some aftermarket sensors. ​ In particular, the 1G EGR temperature input and the 2G baro input have pull up/pull down resistor configurations that some sensors are not capable of driving properly. ​ The solution to this is to "​buffer"​ the input so that the sensor is not directly driving the ECU's input. ​ The circuit and buffer board described below can be used for this purpose. ​ The picture below illustrates the buffer board available for purchase from ECMTuning. 
  
-{{http://www.ecmtuning.com/​images/​forums/typicalinstall.gif}}+There are a number of analog inputs available on the 1G and 2G ECU. Many are used for critical engine operation, but some are available for datalogging [[:externalsensorlist|aftermarket sensors]]The problem is that some of these inputs are incompatible with some aftermarket sensorsIn particular, the 1G EGR temperature input and the 2G baro input have pull up/pull down resistor configurations that some sensors are not capable of driving properly.
  
-**12/​19/​2007:​** We are now accepting orders for these completed units. ​ We have several in stock, ready to ship. 
  
-http://www.ecmtuning.com/​ordering-buffer.html+The solution to this is to "​buffer"​ the input so that the sensor is not directly driving the ECU's inputThe circuit and buffer board described below can be used for this purposeThe picture below illustrates the buffer ​board available for purchase from ECMTuning.
  
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 +{{https://​www.ecmtuning.com/​images/​forums/​typicalinstall.gif?​direct&​}}
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 +**01/​01/​2013:​**Due to low demand, we've decided to discontinue this product. ​ Many common sensors now include this type of functionality internally, negating the need for this board. ​ The Omni 4-bar sensor that we sell on our website, for example, has this functionality built in.  Most, if not all, wideband kits these days do too.
  
 ====== Connections ====== ====== Connections ======
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 Connect "GND to ECU" to the ECU's sensor ground, pin 24 (Green/​Black) on a 1G ECU or pin 92 (Black) on a 2G ECU.  This is also present under the hood at the MAF, TPS, MDP and coolant temp sensors. Connect "GND to ECU" to the ECU's sensor ground, pin 24 (Green/​Black) on a 1G ECU or pin 92 (Black) on a 2G ECU.  This is also present under the hood at the MAF, TPS, MDP and coolant temp sensors.
  
-If the sensor is a 5V sensor that draws little current, like a MAP sensor, connect ​its power, signal and ground connections to the buffer circuit assembly. If the device, such as a wideband, has it'​s ​own power and ground, connect only the signal wire to the device.+If the sensor is a 5V sensor that draws little current, like a MAP sensor, connect ​the sensor'​s ​power, signal and ground connections to the input side of the buffer circuit assembly. If the sensing ​device, such as a wideband, has its own power and ground, connect only the sensing device'​s ​signal wire to the input side of the buffer. In either case, you still must provide +5V and GND to the buffer circuit and you must then insulate any unused wires. 
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-====== Details ======+====== ​DIY Details ======
  
 The following table lists a set of ECU inputs and their internal pull up/pull down resistor configuration. The following table lists a set of ECU inputs and their internal pull up/pull down resistor configuration.
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 | EGRTemp | 10k up | - | | EGRTemp | 10k up | - |
 | Baro | float/100k down? | 3.3k down | | Baro | float/100k down? | 3.3k down |
-| IAT | 2.2k up / 39k down| 2.2k up / 39k down+| IAT | 2.2k up / 39k down | 2.2k up / 39k down | 
-| Coolant | 2.2k up / 39k down| 2.2k up / 39k down|+| Coolant | 2.2k up / 39k down | 2.2k up / 39k down |
 | MDP | - | 100k down | | MDP | - | 100k down |
-| Rear O2 | - | 220K down |+| Rear O2 | - | 220k down |
  
 Again, the EGRTemp on a 1G and the Baro input on a 2G are problematic for some aftermarket sensors. ​ When feeding certain wideband kits into the EGRTemp input on a 1G, for example, you may see normal A/F ratio readings above 11.5:1 but then the readings flatline there and won't show any value below that. Again, the EGRTemp on a 1G and the Baro input on a 2G are problematic for some aftermarket sensors. ​ When feeding certain wideband kits into the EGRTemp input on a 1G, for example, you may see normal A/F ratio readings above 11.5:1 but then the readings flatline there and won't show any value below that.
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 In either case (1G or 2G) and for just about any input, you can also consider using a unity buffer to drive the ECU.  Such a device presents a low-load input for connecting the external sensor and then produces a higher drive output for connecting to the ECU's input. ​ The following schematic can be used to build this device. In either case (1G or 2G) and for just about any input, you can also consider using a unity buffer to drive the ECU.  Such a device presents a low-load input for connecting the external sensor and then produces a higher drive output for connecting to the ECU's input. ​ The following schematic can be used to build this device.
  
-{{http://​www.ecmtuning.com/​images/​forums/​Buffer.JPG|Diagram}}+{{https://​www.ecmtuning.com/​images/​forums/​Buffer.JPG|Diagram}}
  
 Note that this is not necessarily an easy thing to do.  The op-amp part referenced in that diagram is extremely small and difficult to work with if you're not familiar with SMT techniques or have access to appropriate equipment.  ​ Note that this is not necessarily an easy thing to do.  The op-amp part referenced in that diagram is extremely small and difficult to work with if you're not familiar with SMT techniques or have access to appropriate equipment.  ​
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 If you can't wait and working with a SOT23-5 package is just too small for you, then consider this circuit/​chip instead. ​ It's a bit easier to work with. If you can't wait and working with a SOT23-5 package is just too small for you, then consider this circuit/​chip instead. ​ It's a bit easier to work with.
  
-{{http://​www.ecmtuning.com/​images/​forums/​BufferDIP.JPG|Diagram}}+{{https://​www.ecmtuning.com/​images/​forums/​BufferDIP.JPG|Diagram}}
  
ecuinputdata.1202756348.txt.gz · Last modified: 2008/02/11 13:59 by dmertz