Weird reading for temp II sensor.
11-10-2015, 02:34 AM
#1
Rennlist Member
Thread Starter
Weird reading for temp II sensor.
My car smells rich upon startup in the garage. Runs normal when engine are hot.
I measured temp II sensor from 2 pin to ground , both read about 1400 ohm in a flash then drop to 1 in cold engine which is about 68F in my warm S Ca garage. Haven't measured hot yet since I need to find time to take it for a run. Can't figure out why it dropped to zero since these are the # I am referencing. Any ideas? TIA.
From the WSM:
-10C / 14F; 7,000 - 12,000 ohms
20C / 68F: 2,000 - 4,000 ohms
80C / 176F: 250 - 400 ohms
I measured temp II sensor from 2 pin to ground , both read about 1400 ohm in a flash then drop to 1 in cold engine which is about 68F in my warm S Ca garage. Haven't measured hot yet since I need to find time to take it for a run. Can't figure out why it dropped to zero since these are the # I am referencing. Any ideas? TIA.
From the WSM:
-10C / 14F; 7,000 - 12,000 ohms
20C / 68F: 2,000 - 4,000 ohms
80C / 176F: 250 - 400 ohms
Last edited by Bmw635; 11-10-2015 at 09:41 PM.
11-10-2015, 06:34 AM
#2
Nordschleife Master
Pete,
I believe you measure the resistance across the two pins of the sensor, and not outside to a ground. The sensor itself is grounded into the block. This is why the sensor's function can be affected by painting the water bridge and covering the threads by where the sensor grounds to the block
I believe you measure the resistance across the two pins of the sensor, and not outside to a ground. The sensor itself is grounded into the block. This is why the sensor's function can be affected by painting the water bridge and covering the threads by where the sensor grounds to the block
11-10-2015, 08:10 AM
#3
Instructor
Pete,
I believe you measure the resistance across the two pins of the sensor, and not outside to a ground. The sensor itself is grounded into the block. This is why the sensor's function can be affected by painting the water bridge and covering the threads by where the sensor grounds to the block
I believe you measure the resistance across the two pins of the sensor, and not outside to a ground. The sensor itself is grounded into the block. This is why the sensor's function can be affected by painting the water bridge and covering the threads by where the sensor grounds to the block
I took the sensor out and tested in the kitchen at room temperature and in a small cup of boiled water. Each pin to the sensor body.
11-10-2015, 08:28 AM
#4
Pete,
I believe you measure the resistance across the two pins of the sensor, and not outside to a ground. The sensor itself is grounded into the block. This is why the sensor's function can be affected by painting the water bridge and covering the threads by where the sensor grounds to the block
I believe you measure the resistance across the two pins of the sensor, and not outside to a ground. The sensor itself is grounded into the block. This is why the sensor's function can be affected by painting the water bridge and covering the threads by where the sensor grounds to the block
Hugo
11-10-2015, 09:40 AM
#5
Rennlist Member
Rennlist Site Sponsor
My first guess is either operator error or a problem with the Ohmmeter.
There are two sensors in the housing, one for the injection, one for the ignition. They should read pretty close to the same reading. The odds of both having the same strange failure looks pretty low.
As said above, you can measure from each pin to the housing, but it is better to measure from each pin to a good engine ground, to catch any problems with the housing being grounded. Powder-coating can insulate the sensor or the entire water cross-over, resulting in a mysterious running problem.
There are two sensors in the housing, one for the injection, one for the ignition. They should read pretty close to the same reading. The odds of both having the same strange failure looks pretty low.
As said above, you can measure from each pin to the housing, but it is better to measure from each pin to a good engine ground, to catch any problems with the housing being grounded. Powder-coating can insulate the sensor or the entire water cross-over, resulting in a mysterious running problem.
11-10-2015, 09:40 PM
#6
Rennlist Member
Thread Starter
I took the sensor out and cleaned the pin and body. Got measurement of @ 1900 ohm on both pin at 70F, dipped in hot water @ 150F got reading @ 900 ohm, it jump around between 1 and the measured values, depends on my steady hand. It's under spec when cold and over when warm- weird reading?
I have digital ohm meter set to Omega with 1 probe on pin and 1 on brass body- correct? Thanks.
I have digital ohm meter set to Omega with 1 probe on pin and 1 on brass body- correct? Thanks.
11-11-2015, 11:02 PM
#7
Rennlist Member
Thread Starter
Got new sensor installed. Cleaned old sensor pins with sandpaper- measured 1900 ohm consistently. I guess corrosion got to it so I left the new one in there. It ran clean even idling in garage. Thx
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11-12-2015, 03:34 PM
#8
Team Owner
its a good idea to spray the connector with deoxit 100 before final assembly