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--- 2gbaroinputworkaround [2008/01/24 07:23]
twdorris
+++ 2gbaroinputworkaround [2024/03/15 11:16] (current)
@@ Line 1: / Line 1: @@
 ====== 2G Baro Input Workaround ======
-When using something like a MAF translator that allow using DSMLink's Ignore IAT/Baro feature, the ECU's baro sensor input can be used for some aftermarket sensor such as a MAP sensor or a wideband O2 sensor. However, the baro input of the 2G ECU may not be compatible with the aftermarket sensor. The 2G ECU has a 3.3K ohm pull-down resistor (R39). This may put more load on the sensor than it can tolerate and still put out a proper signal. For example, a GM 3-bar sensor can only drive this input to 1.76 volts at maximum pressure. The new Delphi sensor seems to have a bit lower output impedance and will drive the 2G baro input to a little higher voltage at maximum sensor pressure, but it's still unsuitable.
+The baro input of the 2G ECU may not be compatible with aftermarket sensors.  The 2G ECU has a 3.3K ohm pull-down resistor (R39), which may (probably will) put more load on the sensor than it can drive properly.
-Short of removing R39 from the ECU (described below), the 2G baro input is suitable for use only with very low impedance sensors (even a 50-ohm output impedance will produce a little over 1% of voltage offset). Since most sensor designs have a resistor in series with its output for protection, the 2G ECU's baro sensor input is probably not suitable for use with most sensors.
+For example, a GM 3-bar sensor can only drive this input to 1.76 volts at maximum pressure. The GM 3.3-bar sensor seems to have a bit lower output impedance and will drive the 2G baro input a little higher, but it's still unsuitable.
-The 1G baro input doesn't seem to be subject to this problem. It has an input impedance similar to the 2G MDP sensor input's 100K ohms).
+Short of removing that resistor from the ECU (described below), the 2G baro input is suitable for use only with very low impedance sensors (even a 50-ohm output impedance will produce a little over 1% of voltage offset). Since most sensor designs have a resistor in series with its output for protection, the 2G ECU's baro sensor input is probably not suitable for use with most sensors.
+**OMNIPOWER NOTE:** The [[https://www.ecmtuning.com/product_info.php?cPath=28_30&products_id=47|OmniPower 4-bar sensor]] that we sell on our website *does* work fine on the 2G baro input.  This sensor incorporates a buffer circuit that drives the 2G baro input just fine.
+**GM MAF CABLE NOTE:** Also note that our GM MAF cable's "baro" [[gmmafiatbaro|breakout wire]] includes a buffer circuit as well.  So any sensor connected to a GM MAF cable's "baro" wire will work fine as well without having to deal with the 2G ECU's baro input resistor configuration.
+The 1G baro input doesn't seem to suffer from this problem. It has an input impedance similar to the 2G MDP sensor input's 100K ohms).
 **12/19/2007:** Instead of this process, you can also consider using the [[ECUInputData|buffer circuit]].
 ====== Process ======
-If you're really looking to maximize inputs, you can consider removing R39 from the underside of the ECU board. Best to use a couple small-tip soldering irons for this. Heat 'em up, apply one to each side of the resistor and slide it right off. I'm including a picture of the location of the resistor of interest below. I have verified that this does allow a GM 3bar to drive the baro input just fine. Once you have done that, you can use either the baro or the intake air temp inputs for whatever you want.
+If you're really looking to maximize inputs, you can consider removing R39 from the underside of the ECU board.
+It's best to use a couple small-tip soldering irons for this. Heat 'em up, apply one to each side of the resistor and slide it right off. I'm including a picture of the location of the resistor of interest below. I have verified that this does allow a GM 3bar to drive the baro input just fine. Once you have done that, you can use either the baro or the intake air temp inputs for whatever you want.
-{{http://www.dsmlink.com/images/forums/2gbaro.jpg}}
+{{https://www.ecmtuning.com/images/forums/2gbaro.jpg}}

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