 Can YOU test this for me?, resistance vs. temp for stock IAT |
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| McMark |
 Jan 20 2014, 06:53 PM
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#1
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914 Freak!  Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None  |
I haven't been able to find a good graph of the resistance vs. temp for the stock D-Jet intake air temp sensor (IAT). I've never had very good luck trying to measure it directly (hot oil bath with a multimeter). Has anyone done this? Seen a graph (factory or made by someone)? Or is anyone set up to conduct this type of test with accuracy? I can provide the sensor with a wiring pigtail if so. (IMG:style_emoticons/default/beerchug.gif)
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| nathansnathan |
Jan 20 2014, 07:21 PM
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#2
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Senior Member Group: Members Posts: 1,052 Joined: 31-May 10 From: Laguna Beach, CA Member No.: 11,782 Region Association: None |
There used to be a link on pbander's page on d jet troubleshooting, but the links are dead now.
http://members.rennlist.com/pbanders/djetparts.htm QUOTE Function: Senses intake air temperature and sends signal to the ECU to provide mixture compensation. Normal Value(s): 300 ohms @ 68 deg. F, about 100 ohms @ 122 deg. F. Failure Modes Open: Makes the mixture somewhat richer. Check with an ohmmeter. Shorted: Makes the mixture somewhat leaner. Check with an ohmmeter. Notes: The output of this sensor is used by the ECU to adjust the mixture for the intake air temperature. This is a secondary adjustment and has a small effect on the mixture. The sensor corrects for the decrease in air density with increasing temperature by leaning out the mixture. Disconnecting this sensor has the effect of richening the mixture, a common mechanic's trick. More: This sensor and the cylinder head temperature sensor are negative-temperature-coefficient (NTC) thermistors. Here's a URL on thermistors and how they work: http://www.rtie.com/ntc/ntcappln.htm Here's a URL that describes the manufacturing process: http://www.ussensor.com/manufacturing.html Below is a URL to a reference that has two charts showing the resistance vs. temperature relationship for the intake air sensor and the engine temperature sensors used in D-Jetronic. The engine sensor data looks OK (about 2.5K at 68 deg. F), but could be from any sensor. Bosch used the same air temperature sensor on all D-Jetronic cars, regardless of model, so the data should be accurate for the 914's sensor: http://www.icbm.org/erkson/ttt/engine/fuel...tion/d-jet.html The charts are about half way down the page. |
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| Dave_Darling |
Jan 20 2014, 10:10 PM
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#3
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914 Idiot Group: Members Posts: 15,161 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California 
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QUOTE(nathansnathan @ Jan 20 2014, 05:21 PM)  There used to be a link on pbander's page on d jet troubleshooting, but the links are dead now. The Internet Wayback Machine to the rescue!! https://web.archive.org/web/20080916111640/...tion/d-jet.html --DD |
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Posts in this topic
McMark Can YOU test this for me? Jan 20 2014, 06:53 PM
nathansnathan
There used to be a link on pbander's page on... Jan 21 2014, 07:59 AM
worn
I haven't been able to find a good graph of t... Jan 20 2014, 09:02 PM McMark http://www.914world.com/bbs2/uploads_offsite/web.a... Jan 20 2014, 10:35 PM JamesM Mark,
If this is to be used with Megasquirt, it c... Jan 21 2014, 01:52 PM McMark Thanks for the insight James. :thumbsup: I'll... Jan 21 2014, 10:55 PM |
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