hrmm.. i already have a nice laptop how much would it cost to get a log program for it and the ALDL (ADLD?) cables? Thanks

 

I need one yes just one of you guys who have the Hesitasion to replace the Coolant Temp Sensor with a brand new one..... they are about 9.00 dollars brand new.

Why??? I was running some testing in my 95z... I did modify the output of the sensor (made look as if the car was 15degree hotter) it ran fine and the fans came on as expected BUT!!! AND YES ITS A BIG B.U.T.T!!! ........


Next morning when cold it took forever to start!!!


I did let it be for 5 days and 5 times it took forever to start. On the last day it was a slightly colder day and it nearly didnt start at all. I turned her off. Reset the Temp settings to OEM. (you cant do this on OEM i have an electronic device sitting between the sensor and the PCM) I let the car completely cool off till the engine block was at Ambient Temp... this took forever although I never let the engine warm up.


Put the key in the ingnition and she fired right up with authority!!. turned her off immediatelly ... readjust the temp coolant to read 15 degree hotter... Cranked her up again... she turned and turned and turned and finally fired up... I reset the Coolant sensor back and she fired up instantly again.


I get the feeling a Coolant Temp sensor maybe COMPOUNDING to the problem... I do not believe its the coolant temp sensor alone but I need just one guy to check for a bad sensor.


I see everybody is willling to spend over 100.oo dollars swapping parts but not one post here shows any one person replacing a 9.00 dollar sensor.. unless i missed the post.


Mine works fine so I cant tell if thats the problem guys...can anyone replace it and try it???


Marvin

 

Hey guys and gals,

I changed my IAT sensor in the intake elbow this morning and after she got heated up past 220* I had a smooth idle, and no surge in my lower rpms, first time in a long time,

$10.00 part from Sam Taytor, worth a shot?

 

Is there an easy way to test the sensor? Its just a thermosistor isnt it? The resistance should increase as it gets cooler. What resistance should room temperature come in at?

 

GUYSSSSSSSSSS!!!!! I was so close.... but not close enough I guess... There is another guy who replaced the IAT and his problems went away... he said it was reading as if the engine was cold..... and he had all kinds of problems.. now its fixed!!


Also while at it dont forget to replace with a brand new Coolant temp sensor.. maybe those two go bad and some of you guys may have one or the other or even both bad sensors and thats why you all display similar simptoms but there isnt one cure...


The IAT why didnt I think of that?? in my previous post it tells you what happens when the Coolant temp sensor goes bad.. I am telling you this may fix some of you guys problems while the IAT may fix other of you guys problems...


I wil defenetely buy a new IAT so when mine goes I will just swap it...


Marvin

 

i`ve left mine stock ,it runs great but could use more power,no mods.anyway i leave the stock air filter on in the winter and change to the k&n filterpack for the summer,i put to much oil on the filter and got a big puff of smoke on start up and about a week later started geting the low rpm stumble.it got worse when the girl friend put in ragular gas in,a/c on,hot day,low gas level situation.i`ve read all the posts and think my problem is that oil on the maf and iat,it ran fine before the k&n

 

I have a brand spanking new Sensor hooked up to my Digital MultiMeter and firmly held together to a Temperature Meter

I am in Hawaii so please excuse the High ambient temp ...

this is the resistance.. 2347 Ohm or 2.347 Kilo Ohm at 86.9 degree farenheit...


Whats your room Temp?? I have recorded the readings all the way up to 208* farenheit.... the water was boiling so much that I could not go up any higher...


Anyway at 60degree 4322 ohm
at 65 degree 3784 ohm
at 70 degree 3426 ohm
at 75 degree 3022 ohm

these are not dead center numbers...for example in the 75 degree range.... like 75.1 through 75.9 degree your readings should be from 3073 ohms all the way to 3006 ohms...

yes it took time but I was taking readings at the 0.1 resolution level...

Obvioulsly I have nothing better to do huh??




Marvin

 

Well i plotted the range out in Excel and eyballed a few more points along the curve. Your temp sense in ohms should be fairly close to this:
F Ohms
50 5398
55 4860
60 4322
65 3784
70 3426
75 3022
80 2700
85 2440
90 2200

Mental Case one .. you rule! Thnx for the #'s

http://csce.uark.edu/~jgbertr/rb/4th_gen_tech2.html#ect
This seems pretty much the same as the resitance of the ECT found on shoebox's site...

 

Well i plotted the range out in Excel and eyballed a few more points along the curve. Your temp sense in ohms should be fairly close to this:
F Ohms
50 5398
55 4860
60 4322
65 3784
70 3426
75 3022
80 2700
85 2440
90 2200

Hey dude my reading at 90 degree is 2086 ohms... that is only 114 ohms diff and that represents a tiny 5 percent deviation. I dont know what the tolerance of our Sensors are but that to me is an acceptable number either yours or mine.... nifty lil program you got there...

oh there is a formula to calculate the Thermistors points,,, its called the Steinhart-Hart equation...

Ln (R(T)) = A + B/T

where T is degrees in Kelvin, R is ohms and A and B
are temp/resistance for two known data points of a given thermistor


example... a= 285.0944*K /4999 Ohms
B=312.0389* K/1581 Ohms

I used the above formula with these given numbers and I came up dead center to my readings.... I was amazed since I know my thermistor can not be that precise... it must have some type of tolerance/deviation but I was like wow...anyway... I would say 5 percent is an aceptable tolerance...

If only I had thought of using excell instead of a hand held calculator....

I guess I have too much time on my hands huh??

cool job dude.. oh by the way Maybe I can use that webpage numbers to draw the aproximate tolerance of our Coolant temp sensors...... or can we just contact a GM engineer??

Marvin

 

What was involved in changing this sensor, did you have to drain coolant? Also where is it. Seems to be the only sensor Chilton doesn't have an illustration for.

Thanks.

 

The sensor is mounted on the water pump. Do not confuse it with the sensor located on the engine block.... The water pump sensor is on the front of the engine block... since you have to remove coolant this would be a perfect time to replace the coolant altogether..

Shoebox has a picture of it I believe... check his webpage. You cant miss... its the only sensor on the water pump and its located directly below the rubber bellows about 5 incens down bellow... just follow the wires that conect to the IAT, the run along with the Coolant sensor...and split by bellows.. you cant miss it.


Marvin

 

the coolant temp sensor can cause the car to run like crap??? thats crazy. well heres my deal, tell me what you think......
at night and in the morning (sun isnt blaring) the car runs PERFECT (AF guage lights up at startup) but during the day when the sun is at its worst, the AF gauge doesnt light up and the car runs really crappy after warm up.

MentalCaseOne....pm'ed ya

 

I'm jumping in on the end of this but I have a quesion, did anyone have problems with their car dying? My car has the infamous 1000-2000 stumble occasionally, and now it's started to die. you can only drive it like 100 ft without it cutting out. The SES light hasn't come on, so I'm at a loss on where to start. Suggestions?

 

Fuel Pump perhaps.. along with bad injectors?Tiz only a guess...

 

For those or you with higher mileage, you may be getting oil blow-by past the rings. This will end up in the throttle body area. take some carb cleaner and a toothbrush and clean the TB and blades, use electrical cleaner for the MAF and the IAT. This should help some of you who find oil around the throttle body and elbow.