Well, I havent done ANY PROM burning yet, and really the only thing I would do (in the near future), would be lower the fan turn on temp. It this possible fer the L03's comp? Or no? Also, how expensive would it be to get started burning PROMs? Thanks fer any input!

 

Start by reading this --> https://www.thirdgen.org/newdesign/tech/promintro.shtml

 

well, it seems quite cost prohibitive considering my meager goals. I'll just have to settle fer a low temp fan switch...

 

The L03 ECM does not control the fan. A lower temp fan switch is the way to do it.

 

Well, yes, and no. The ECM turns the fan on when the temp reaches 228*, or when the AC is on. the fan switch turns the fan on when the temp hits 240* (about). Stock. Its really not worth it for just the temp - you right, go with the fan switch - but if I was gonna burn a custom prom, I am pretty sure (not positive though), that i could change the fan on temp. I was talking to some guy (forgot who) who did this, but then again, he didnt say which ECM, just that he had a 91 Camaro, it coulda been TPI (but then why does my fan come on @ 228, and if that dont work, 240??).

Edit: thats confusing - lemme try to clean up about the 2 temps
Primary - a control unit (ECM?) turns fan on at 228* (about)
Secondary - If primary fails, a completely seperate unit turns fan on at about 240*
Thats better...

 

Maybe I wasn't clear the first time. The LO3 TBI ECM doesn't have any control over the cooling fan. Check your wiring diagram.

Only the TPI ECM's control the fans.

 

OK. Since I do not know for sure (just heard it) I will take your word for it!
But, in that case, explain why my fan dont come on till 240*! I do not understand - it that how high it is SUPPOSED to come on, or is that just what happens when the fan temp sensor gets old and crusty? Probably the second one, no? Well, I am gonna put a 180* thermo in soon, and a 200* switch in when I do my cam swap (I dont really like the idea of draining my cooling on day after school, or worse, one day after work!)...

 

240? Two possible reasons. One, the stock gauges/senders are not known for their accuracy. Two, the fan switch is failing or not accurate.

Don't take my word for it, check the wiring diagram. If you don't have a service manual of some type then get one ASAP.

 

Yeah, I figure once I find my Chiltons (in my rooom SOMEWHERE...), I'll double check the diagrams. Now, whats got me PUZZLED, is the first time it hits 220 after starting up, the temp drops down to like, I dunno, 190 or 200. W/o fan coming on...But the thermo is pretty new - think it could be shot already. Well, it dont matter, I am gonna put a 180 in when I get a few spare minutes...

 

Brent - I don't have a wiring diagram handy, so maybe you can enlighten me... I read your post and thought, exactly, that fan is controlled by the fan sw, not the ECM. Then I thought about A/C turning the fan on, too, and wondered how the that happens - I guess it must hit the same fan relay? Is there a wire from the A/C/heater controls or is it from elsewhere? Sorry, just curious...

 

The '92 LO3 has three possible "triggers" for the fan relay. The fan switch, the HVAC control head and the A/C pressure switch. They all are wired directly to the relay.

The earlier ones don't appear to use the A/C pressure switch.

 

OK, whats the HVAC??? Cuz My fan comes on @ about 240* and when AC is on, so it MUST be HVAC, but what is it?

 

Thanks, Brent.

Buick, HVAC stands for Heating Ventilation and Air Conditioning. I think Brent was referring to the heat/vent/A/C controls in your console above the radio. If your fan is coming on (in the abscence of turning on your A/C), that is most likely your fan switch turning it on... perhaps your temperature guage is off? If your temp guage is correct and the fan switch isn't kicking the fan on until 240*F, you can just get a stock replacement fan switch for $20 or so at any parts store, to bring it down to normal.

Or, check out my thread in Tech/Gen. Engine re. lower-temp options...

 

well, it does come on w/o ac. How would I check the gauge? I cannot start car w/o the ECM temp sensor plugged in, and what good would it do if I unplugged the guage from its sensor, ya know?

 

Could you measure the temp of the fluid at its entry to the radiator? That should give a decent approximation... if it's the same as what your guage is reading, replace the fan switch. If it's lower, replace your temp. guage sensor.

 

well, i guess since its like freezing out, I'll just wait untill I swap my cam in (about 2 weeks, spring break). Then I'll throw a 180 thermo, and a 200 fan switch in...