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Coolant temp sensor question http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=90032	Page 1 of 1

Author:	mike71800b [ Tue May 21, 2019 2:03 am ]
Post subject:	Coolant temp sensor question
Im looking for the temp/resistance values of the coolant temp sensor. Spent a while last night looking through the 2006 fsm and didn't see it. Im running a chinese thermostat with torque pro showing 176 deg operating temp with a short duration bump to 180 after a full blast 0-60 so i presume the temp is accurate... my ir gun shows the stat housing at 170 by the time i get stopped and under the hood. Point of this is i would like to lie to the ecm with a resistor value equivalent of say 195f and take a cruise and see if it affects the mpg. If it does ill crack open my dead factory housing and machine it for the hemi tstat. Thanks for any feedback in advance guys

Author:	flash7210 [ Tue May 21, 2019 5:36 am ]
Post subject:	Re: Coolant temp sensor question
Instead of a fixed value resistor, use a variable resistor. Dial it in till you get the desired effect, then measure the resistance. I’ve done it. Not with the temp sensor but with other sensors.

Author:	mike71800b [ Tue May 21, 2019 8:33 am ]
Post subject:	Re: Coolant temp sensor question
Thats the intention, but i also know the ecm has protective measures over 215f or so... Thought i may have been overlooking a chart or value table somewhere in the service manuals. I'd just pull it and plot T/R if i knew it to be 100% accurate sensor

Author:	flash7210 [ Tue May 21, 2019 8:50 am ]
Post subject:	Re: Coolant temp sensor question
I really don't see the point in modifying the temp output signal. Not only are you lying to the ECU, but you're lying to yourself. No real performance to be gained. Overall engine temperature is more about the combustion process and less about what the ECU manages. Myself, I've tried the factory 170F thermostat, a 180F, and a 195F. Noticed no real difference in MPG or performance. But I live in Florida. I'm more concerned with keeping the engine cool on a hot summer afternoon. Now I have wired in variable resistors in with the MAP and IAT sensors and have noticed some small but improved changes in performance.

Author:	mike71800b [ Tue May 21, 2019 9:38 am ]
Post subject:	Re: Coolant temp sensor question
Found some datasheets on NTC coolant sensors from bosch, seems to have a trend of these values 80c=.323k 90c=.243k 100c=.187k What mpg are you seeing from your rig and how is it set up? I'm in middle georgia so not too far from you. Yeah I get it that the temp sensor is measuring heat shed off into the coolant system but the ecu temp/fueling map is what i desire to manipulate. I'm not convinced btu lost into the coolant system vs work done efficiently is greater than getting to a more favorable temp/fueling table value from the ecm. I do find it interesting you had no mpg difference b/t the 170f and 195f thermostats though. Reading thermostat threads there were lots of mpg increases mentioned with hotter and proper working thermostats whether custom hacks of factory housings or the $$$ cnc unit. What am i getting at here? I'd like a few more mpg... replacing the failed open tstat moved me from 17 to ~20 mpg but i have yet to break a best of 22mpg and i think that one time was just a filling fluke from uneven ground 2006 120k miles, f37 ofc.... Stock sized street tires 40psi, alignment seems good... hands off no pull and no uneven wear on tires, no lift, verified no brake drag with ir gun, no symptoms of boost loss oily hoses etc, 5w40 t6, boost peak 22psi on torque pro, mbrp stainless exhaust... the cobbled and clamped together straight pipe it came with was no better either. Full throttle accel gives a light haze and no coal rolling... no lifter noise very quiet valve train. Pulled the heater wire to the filter head and filled that with rtv... no more air in fuel. Running a stock tune with egr/fcv delete at the moment, all other free tunes give some converter shudder and worse mpg. The viscous heater gave a little mpg boost in the winter but really it was worth keeping for fast cabin heat. Just looking to break the 25mpg mark without spending big bux with GDE eco tune... takes a whole lotta miles to make up the cost difference. Anything i am missing here as i dont drive it hard and try to keep rpm under 2.2k seeking mpg?

Author:	flash7210 [ Tue May 21, 2019 12:06 pm ]
Post subject:	Re: Coolant temp sensor question
Could be a lot of things. When was the last time you changed your fuel filter? Air filter? Have you checked the filter box to turbo inlet hose? Even though you plugged the filter head, a lift pump might help. Do you use any kind of fuel additive like PowerService? I average 26mpg on long highway trips. Normal city driving is 24mpg. Most of the things I've done really haven't changed that. I'm lifted with tall heavy tires. Viscous heater delete and removed engine driven fan. Electric fan only. Currently using Shell T5 15w-40 oil. Straight pipe exhaust, GDE Eco tune (I've tried all the free 811 tunes also), and I've suffered through and repaired several fuel system problems. My worst MPG was during a winter cross-country trip. Averaged about 20mpg. But that was with a roof rack and about 600 lbs of extra people and gear. My wifes 06 CRD should theoretically do better than mine. Hers is still pretty much stock, with EGR delete, and only gets 24mpg. But she mainly uses it to get groceries although we occasionaly take it on long trips.

Author:	flash7210 [ Tue May 21, 2019 12:30 pm ]
Post subject:	Re: Coolant temp sensor question
PM sent

Author:	mike71800b [ Tue May 21, 2019 6:32 pm ]
Post subject:	Re: Coolant temp sensor question
Could be a lot of things. When was the last time you changed your fuel filter? New Air filter? New I've had the libby almost 5k miles now. Have you checked the filter box to turbo inlet hose? Yes no holes MAP cleaned presumed working with seeing 22lbs in torque pro. Even though you plugged the filter head, a lift pump might help. Its under consideration Do you use any kind of fuel additive like PowerService? First 10 fillups or so. We have very clean diesel here and filters often last way way longer than recomended intervals, always 100% diesel no wvo or bio. What i havent done is gut the FCV and blockoff plate the egr... not looking forward to all those hard to get to fasteners. My other diesels include 7.3 Excursion (2) c223T powered troopers 2004 TDI Golf

Author:	layback40 [ Tue May 21, 2019 11:46 pm ]
Post subject:	Re: Coolant temp sensor question
You will find the thermistor in the sensor is a very standard one. I have replaced the thermistors in both sensors in my XJ diesel following issues with one of them failing. They are a 50c max part at any electronics parts store.

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