coolant temp sensor, sender questions

[modelageek]

Is there a reason for testing the sensors. if you just want to find the one for the pcm unplug them one at a time while the engine is warm when the guage dont register you know which is which or if you need the one for the guage unplug them one at a time and take it for a spin if it runs crappy thats for the pcm. If you change the pcm sensor disconnect the battery for an hour then drive it at medium speed for a while to set new values.

I know which sensor is the ect(pcm) sensor . I just had a hard time finding what the resistance should be. I found that out now i am trying to see if it is off enough to matter

 

[kimcrwbr1]

when you clean a sensor it is the same as changing one you still need to reset the values it might be still running on the old ones.

 

[modelageek]

kinda doubt it, but if you want to try i think they're only like 5-10 bucks at autozone.

yeh $17 at Advanced. I guess I have OCD about putting in a part unless I need it....lol.....it is a personal weird challenge. I like putting in maintenance parts.....maybe i should look at it as maintenance.

 

[Bryan22]

i don't know hard to say without having something solid to base ur findings on. i've never read anywhere that had a set number for what the CTS should test at.

 

[modelageek]

when you clean a sensor it is the same as changing one you still need to reset the values it might be still running on the old ones.

yesterday i reset the pcm after i cleaned the iac. this morning i only tested the ect? I agree it is always good to reset the pcm

 

[modelageek]

i don't know hard to say without having something solid to base ur findings on. i've never read anywhere that had a set number for what the CTS should test at.

http://fordfuelinjection.com/?p=28 Rockledge got this for me it tells you exactly what it is suppose to be.

 

[kimcrwbr1]

Take it for a good beat too if a plug looks dirty pour about a cup or so of water down the TB at a medium rpm to clean the cylinders out

 

[Bryan22]

it seems like it's working then. i wouldn't waste the money, start looking at something else.

 

[modelageek]

it seems like it's working then. i wouldn't waste the money, start looking at something else.

I actually was reading how the fuel injection and the pcm works from that website. I think my ect might be off enough to mess with it. my 105,000 tells me the engine should be 30 below zero F

 

[rurouni20xx]

in other words your running a high resistance fault. your computer will then do one of 3 things (this is in a bike idk about a truck so plz bear with me), either throw a cel with a temp resistance fault (i dont think the truck is programmed for this) and/or ignore that reading and run with a last known good value (usually 65-70 degrees) or act normally and run rich as hell. sorry was busy this wknd, and yes bob i kno of ohms law, but if you read the manuals and take fuel injection classes as i have you kno that this is how the system operates.

 

[Bob Ayers]

and yes bob i kno of ohms law, but if you read the manuals and take fuel injection classes as i have you kno that this is how the system operates.

Obviously, you were asleep when the PCM internal voltage regulators for the sensors were discussed!!

There is NO WAY they will source 21 AMPS!!!!!!

DUH!!!!

 

[modelageek]

I installed a new ect sensor yesterday this morning it read 85,000 ohms. 20,000 less ohms then the old sensor did whenit was dead cold( both days the temp was about the same 25 degrees F. I think I am going ot look into a scanner. does anyone have any suggestion about what scanner i would need to read live( I am not sure if it needs to be live) data on fuel injectors, o2 sensors, iacv, maf, etc. any suggestions would be aprreciated. would the Innova Equus 3160 do it. http://www.google.com/products/cata...ct=result&resnum=3&ved=0CCMQ8wIwAg#ps-sellers

 

[cf3232]

oops i was reading the mm wrong. the correct readings are temp gauge sender=21,000 ohms(cold), 130 ohms(hot)

engine coolant temp sensor(pcm)=105,000 ohms(cold), 3,100 ohms (hot)

are these within spec

Gauge sender unit is not important to get the truck to run. Your temp gauge would just read wrong if it was malfunctioning. If your temp gauge is showing correct when you drive then the sensor should be fine.

But your engine coolant sensor should be around 4K Ohms at normal operating temp. Mine was around 67K Ohms at 40 degrees Fahrenheit. It will be different at different temps, but it should get lower the warmer it is. There is a scale for this that I found online, but i can not find it now.

Just read the post before this one. If yoiu were at 80,000 Ohms at 25 degrees that sounds like it is within specs to me. AS it gets warmer that number will drop.

 

[modelageek]

Gauge sender unit is not important to get the truck to run. Your temp gauge would just read wrong if it was malfunctioning. If your temp gauge is showing correct when you drive then the sensor should be fine.

But your engine coolant sensor should be around 4K Ohms at normal operating temp. Mine was around 67K Ohms at 40 degrees Fahrenheit. It will be different at different temps, but it should get lower the warmer it is. There is a scale for this that I found online, but i can not find it now.

mine was off a little on the high end(cold) but on the low end(hot) it was fine. I replaced it anyways. I think the site you want is http://fordfuelinjection.com/?p=28site

 

[rurouni20xx]

bob, nothing personal, but the way i learned it (and apparently this is how it works) is as resistance increases in the sensor voltage drops (we are only working with 5v nots 12 or more) and the computer sees this and reads the specified voltage as a certain temperature. it then trims the map etc accordingly. not starting an argument here thats what classes and real world field work/testing shows. this is true with all sorts of variable resistance sensors including angle sensors (tps for example) heat elements (coolant temp sensors/mafs/o2 sensors/and eot sensors if equipped).