General & Model Specific Technical Forums > Twin Cam
Head Temp Sensor
rbabos:
I understand they can fail and cause rich mixture but can they fail as in being lazy in resistance changes or even become erratic at times without throwing a code? Sometimes my engine , even though it's still quite warm will jump into high idle and rich afr when starting it up. Seems to take forever for the idle to return to normal when riding but one full stop it will eventually drop and stay there. From a cold start all the way to hot it seems to behave normally. Can they be flakey and cause this odd behaviour? All other sensors have been changed as in iat , tps, map, and vss. The only original left is the head temp which spent a couple years being baked in a stock 07 96"
Ron
rigidthumper:
I've replaced 4 in ten years. 3 of those in the past few weeks. No codes, fouled plugs.
hogdoctor:
Absolutely. The computer only flags a code if it's shorted, grounded or out of the normal range. If it's reading incorrectly in it's "normal" range, you don't get a code, just crappy fuel mixture.
It can shift all of it's temperature signal range, or it can spike/drop at certain points, usually where it hangs out the most in normal operation. I screw the temp sensor into a block of metal, with a thermoprobe in the block and an analog ohmmeter connected to the sensor, and use a small butane torch to heat the sensor from cold to hot, watching the ohmmeter for dips or spikes, confirm it's max reading is correct, then watch it cool back down slowly. Often it will hiccup either cooling or heating, but not both.
rbabos:
--- Quote from: hogdoctor on Wednesday, August 01, 2012. 10:18:43 PM. ---Absolutely. The computer only flags a code if it's shorted, grounded or out of the normal range. If it's reading incorrectly in it's "normal" range, you don't get a code, just crappy fuel mixture.
It can shift all of it's temperature signal range, or it can spike/drop at certain points, usually where it hangs out the most in normal operation. I screw the temp sensor into a block of metal, with a thermoprobe in the block and an analog ohmmeter connected to the sensor, and use a small butane torch to heat the sensor from cold to hot, watching the ohmmeter for dips or spikes, confirm it's max reading is correct, then watch it cool back down slowly. Often it will hiccup either cooling or heating, but not both.
--- End quote ---
Interesting. I think I will pick up a new one and try it. Seems this one is not stable in some way. Thanks.
Ron
koko3052:
Should be perfect for the average harley rider then...unstable! :hyst: :hyst: :hyst:
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