87camz28

I have searched the boards but can't find a good solid answer.

I have a L98 with the Hypercrap Thermomaster chip, I know piece of crap, I just got the stuff to start burning my own PROM's! Hypertech says to use a 160* t-stat, which I have along with the fan switch that turns the fans on sooner (also have this).

In spring and fall mornings and winter, my temp never gets above 150* and engine periodically runs rough. In the South Carolina summer it runs okay (btwn 160* to 190* while crusing). Sometimes in the hot summer afternoon in traffic it runs btwn 220* and 250*. My thinking is that a 180* t-stat will allow the coolant to stay in the radiator longer and keep the temps at 220* and below in hot summer traffic, and at the same time give me decent temps in the morning and while cruising. My question is, will it be okay to run the 180* t-stat with the Thermomaster PROM and the cooler fan switch until I can burn a new PROM, or should I just leave the 160* t-stat in until I burn a new PROM?

vernw

iTrader: (2)

I'd leave the 160 in if it was me (I did). A 160 thermostat just starts opening up at 160. A thermostat usually takes 15 degrees or so to totally open, so that would have it all the way open at 175 or so. Do you have the fan switch in now? If you do, I'd wonder if it's working or not. It shouldn't be getting that warm if the fan is running. Best situation after you get your prom burning under way (mine is on the way to me as well), may end up being the lower fan switch and the 180 since EFI supposedly like slightly warmer temps, but most folks stay with a 160 from what I've heard.

Which fan switch did you get? I just installed the one that comes on at 200 and off at like 180. On my 91 Formula it's controlling the second fan, the CPU controls the primary fan on mine and it's set to come on at 170 in my 3rd party custom prom.

Good Luck!


- Vern

87camz28

I have the Hypertech fan switch PN 4026 (on@ 176* off@166*), and it does work b/c when the temp is just above the 160* mark on the gauge the second fan is on. I have it set up where this switch controls the second fan and the CPU controls the primary fan just like yours, only my primary fan comes on at the stock setting, which I think is around 237*, it also works.

I think I might just try to reduce the amount of water/coolant mixture and add some water wetter. Right now I am about 50/50.

vernw

iTrader: (2)

I use the 50/50 setup as well and I'm in Dallas, TX. That should be fine, don't think I'd mess with that. First thing I'd do when you get the prom equipment is lower the primary fan to 170 or so. Running 220 with an accelerated timing curve like hypercrap does is just asking for pinging I think. Were you using the new fan switch when it got that hot last summer? If not, I'd just change the fan on temp and see what it does when it warms up to summer temps.


- Vern

87camz28

I just converted it from an stock LB9 to the slightly modified L98 late this past fall. Last summer the stock LB9 was running btwn 190* and 220*.

The Hypercrap was a freebie from a friend, and actually turned out to be a stage III chip that they don't make anymore. Hypertech said it was just like the Thermomaster except that I could delete the egr, cat, & smog pump and not get an ses light, and I don't.

As long as I am moving on the freeway or around town, the L98 stays btwn 160* and 190*. I do still have the air dam and the radiator is new and not blocked by anything.

I have even thought about wiring the primary fan into the secondary fan circuit so that they will both come on with the fan switch, but I think I would rather have it controlled by a porperly tuned PROM.

vernw

iTrader: (2)

If I read this right, then you haven't run the new setup in the summer yet and don't know how hot it will be. I'd just leave in the 160* thermostat, and burn a new prom with a 170 primary fan on temp when you get the stuff, and wait and see if you even have a problem.


- Vern

87camz28

Vern,

That's correct. We have seen a couple of day in the high 80's to low 90's, and the temp climbing btwn 220* to 250* during very heavy traffic is what concerns me. It usually is around 100* here in the summer. I agree though the custom chip is a better route. I just wanted to see what someone else thought.

Thanks

DJP87Z28

With your 180 deg T-stat the only difference your fan will run below 35 mph and turn off above that speed. Thats what happens with my Fastchip Stage 11. And I run below 200 with the air turned off.

87camz28

Thanks for the info DJP87Z28.

I am thinking about changing to the 180*, everything I've read says you get more consistent performance from this t-stat. I still plan on running a custom burned chip also.

LAFireboyd

iTrader: (3)

Hi. I don't mean to butt in, but I was just surfing through the board, and this got my attention. I'm wondering how or why it is that your computer is turning on your primary at such a high temp.

Perhaps you already know this, or maybe I'm wrong, but as I understand it, the Hypertech chip is supposed to be programmed to turn on your primary fan at 176* and off at 166*, same temps that the fan switch operates at. Did you somehow reprogram the Hypertech chip to the gm stock on temp? Are they even reprogrammable? If your chip hasn't been reprogrammed, then I'd think it's malfunctioning.

It's set that way so both fans will operate together. As you've already experienced, it's difficult for only one fan to keep temps that low in traffic. One can hold it close and can keep it from getting too hot, but it'll be on all the time, as I think your secondary fan is now. On the freeway, neither should be on, as the engine temp should be at or below 160*. But in traffic, it needs help from the other fan to actually cool and shut off, which is ideally what you'd want, I think.

And putting in a higher temp stat than the fan(s) are set for will allow the engine to run hotter all the time--even on the freeway, not just in traffic. That'll put ALL the burden on at least one fan, which will be on all the time trying to fight the temp that the engine's being allowed to run at by the stat. You'd run the risk of burning out your fan motors or relay that way. And that never happens near home, lol.

Like I said, I didn't mean to butt in, and I might even be wrong, but I thought I'd check in.

87camz28

From everything that I have read, (1) fan is controlled by the fan switch, and the other fan is controlled by a switch that is tied into the air conditioning system. As far as I know the Hypertech chip does not change the way the system operates. The factory setting for the fan that activates with the air on is 237*. I am thinking about wiring the air conditioning fan to come on with the fan switch like the other fan. Like you say, in hot weather it's too much for 1 fan.

LAFireboyd

iTrader: (3)

I broke up your quotes to make it easier to follow, I wasn't trying to be an @$$, lol. I don't even know if this will come out like I'm thinking, so it might look a bit strange and might end up being editted alot.

Correct, the secondary fan. The Hypertech switch is on at 176*. The factory switch was on around 237*.

[QUOTE]Originally posted by 87camz28
and the other fan is controlled by a switch that is tied into the air conditioning system...The factory setting for the fan that activates with the air on is 237*[QUOTE]

Partially correct. The switch you're referring to that's controlled by the A/C is the pressure switch. It controls the secondary fan, overriding the switch(although I believe both fans run when the A/C is turned on). And again, that factory fan switch on temp was 237*. But if the switch was changed, it should now be 176*. So I'm thinking your fan switch wasn't actually changed, as you've been led to believe, and that you might have your fans mixed up for the discussion.

The "other" fan, being the primary fan for this discussion(since we've already covered the secodary fan), is controlled by the computer. The factory chip's programming was around 222*, Hypertech's programming should be 176*(same as its fan switch).

Correct, it does not change the way the system operates. It only reprograms the on temp for the primary fan to 176*. The factory chip's programming was around 222*, which is why I said I think something's wrong with your chip since you said your primary fan isn't on until 237*. So again, I'm wondering if you simply have the fans mixed up in your mind. It can be very confusing.

So with the computer chip turning on your primary fan at 176*, and the fan switch turning on the secondary fan also at 176*, your engine would stay cool. That's how it's supposed to work.

As I said in my first post, your situation got my attention. And the reason it got my attention is because I've just done all this. And just to be sure I was understanding it correctly when I was doing it, I phoned Hypertech and discussed this with them. That's how they told me it works, and that's how mine works. So that's why I'm thinking you either have your fans mixed up or something isn't operating correctly for you.

Sorry for the length of this, lol. And as I said, it wasn't meant to critisize, as that's not my style. I was only offering some assistance.

87camz28

LAFireboyd,

Thanks for the info. When I bought the car the guy that had it before me had wired everything to a manual switch. I wanted it to be right, so I put it back the way I thought the wiring diagram indicated was correct. I could have made a mistake, so I am going to go back over the wiring again to see if there is a problem.

Thanks again for the help.

LAFireboyd

iTrader: (3)

Hmm, I've been trying to think about how you might've miswired it, and I don't think you could've. I think you've either got a bad coolant temp sensor, or your wiring connection to it isn't good.

The only problem you're having is that your primary fan isn't working with the computer like it's supposed to. And it's supposed to work off of the coolant temp sensor on the front of the intake manifold. That feeds the computer and operates the primary fan. But yours isn't doing that.

It does however work when the A/C is on. And that's because the pressure switch is overriding the temp sensor. So that means the pressure switch is operating properly.

And you do have the Hypertech fan switch installed, and it's also working properly because the secondary fan is on at 176*.

So that only leaves the computer or the coolant temp sensor. One is malfunctioning. It's probably the sensor or its wires.

The only thing you could've done was to reverse the connectors to the fan switch and temp sensor. But I don't think the wiring harness could reach to do that. So it can't be that. I think you've done it right, and it's the sensor.

Be sure to post what you find. I'm very curious.

87camz28

LAFireboyd,

I think you could be right. I double checked the wiring and it is correct as well as all of the connections.

I am going to replace the coolant temp sensor, when I have time. I am working on redoing the front brakes now. I also have a spare ECM I can try if it is not the sensor. You are probably right though, that may be why the guy that owned it before me put the fans on a manual switch.

87camz28

I found out what was wrong with my secondary fan (fan that runs off of the A/C pressure switch). The Primary fan that is controlled by the fan switch in the passenger side head is working fine and coming on when it is supposed to. The secondary fan that runs off of the A/C pressure switch was not working due to the A/C Pressure switch being faulty. It is now fixed and both fans opperate properly. Thanks to everyone for the help.