A 50/50 mixture of coolant should not "bubble out" at 240*F under an 18psi cap.

 

it redlines at 260 degrees, i have a brand new ac delco 18 psi cap, the cap is fine it just bubbles out the overflow. i think my pcm isnt send a signal to my fans or something. i have checked every possible thing besides scanning it.

 

I always had problems with my fans not coming on and my car would overheat sitting still-You know what i did.....I put in a 180* thermotstat and drained the coolant, refilled with new and put in a fan switch and havent had a problem since. I turn the fans on when the car reaches 175ish and leave them on when I am running around town-if I am on the highway I turn them off the airflow through the radiator seems more than adequate will travelling at speed

You could have the car scanned and see whats goin on there, that would help out alot I imagine-if everything seems normal i would look into a getting you ECM reprogrammed to have the fans come on sooner

 

Exactly what you should have already done.

 

http://shbox.com/1/temp_sensor1.jpg

If there is something wrong with this sensor, the connection, or the wiring... your PCM may have trouble knowing when to turn on the fans.

 

i have aleady

checked fusese
continuity test and circuit tested relays and the whole fuse box and fuses, also have checked the sensors at the fans and i got nothing on the ohm meter, i have jumped the fans and they turn on, put a new engine temp sensor (water pump sensor) in it. i have used the dlc to field check sensors for sanity check fans worked then too. i took out the thermostat and boiled it looks fine opens fine. i have drained and flushed the radiator twice. there is a couple more things but i am haveing a brain fart. look through the threas to find anything i didnt mention. but i think the only thing i didnt do is scan it bause i dont have accsess to a scanner. anyone live in arnold or south county with a scanner????

 

Check posts by me about my fan problem a while back. I checked everything and they wouldnt come on until I got my PCM retuned and walla they worked. I think it is a glitch in the factory pcm.

 

I had the same problem. Bought LT1edit and reloaded the stock flash and the fans worked. Then I lowered the turn-on temp to 165.

You could trick the temp sensor to turn the fans on earlier. look at the shoebox write up and install a resistor in the temp sensor. make th eengine "think" it's hotter than it is.

Or, next time someone sells LT1_edit, buy it. (or pay 450 and get your own new set..)

wait in a 1995? you might be able to get the cheap version of software. I would do that.

and you could put a switch on the fans.....

(and I talked to Jazsun too...)

 

My fans never come on ever since I bought the car about 3 years. I do short trips though.Change everything in my car and no luck. Im just gonna buy a damn switch so the fans go on. Im so good with my car that I can tell you how hot m,y car runs becuase once an LT1 runs at 210-220 the pcm retards the timing and I can feel and hear when it is running or at idle.

 

well still no luck. i checked the engine coolant temp sensor wires (black and yellow) for electrical current with a meter from the tip of the engine collant sensor plug to the PCM and everything read fine. i checked a spot on the wires every 6-10inches. but when i unplug the engine coolant sensor the fans come on. i thought that indicated a broken or bad wire, but not this time. its just tricking the engine to tell it that "its hot" and the fans turn on then. Any other suggestions. i dont want to rig a fan switch up, but i want it fixed. Diagnostic are from 60-95 dollars per hour. i dont want to spend that much money on my damn fans. i will just have to be patient and figure it out.

 

i had the same problem with my fans not turning on 94 z28 a4 i will take pictures today and show you how i cured my problem..

 

ITS THE PCM! Many people have had this problem. Go get a performance tune from pcmforless of madz28 and it should fix your problem, and if it doesn't oh well you just gained 15rwhp anyways. I run a switch on my fans as well, for low and high. Its nice for bumper-bumper traffic I just keep the low fan on all the time. Especially nice for staging lanes at the track.

 

It's not the PCM until he has verified with a scanner that when the fans are commanded on, there is no ground coming out of the PCM to operate the relay(s).

 

All i had to do was get some wire and plug it in, I baught a new relay still didnt come on, it sounds weird but i will post the pictures tonite. i got tired of having to lift my hood every time i parked to turn off the fan, so i hooked up a switch it took less than 10mins. i did everything myself and all i had to buy was the switch 5 dollars home depot, and wire had some laying around.

 

I don't think he needs a way to wire in a fan switch. There are plenty of solutions for that out there (including my Tech Page). I think he wants them to work as they are supposed to.