Chevy86 IROC-Z

iTrader: (17)

Hi guys. It has come to my attention that my single fan 86 IROC had only one method of powering the single cooling fan. Im aware that the ECM has a turn on lead that triggers the fan to turn on at 220* and Im also aware that there is the temperature switch that bolts into the passenger side cylinder head. So my question is, which method was used out of the factory? ECM or cylinderhead?

Also which way is the best route? ECM or cylinderhead?
Thanks guys for your help.

Awesome-X

If I had a choice between the two I'd go with the temp sensor method. If the fans should ever stop working it would be easy to figure out and easy to replace. Just my

Chevy86 IROC-Z

iTrader: (17)

I think u meant temp switch. But very good point. Thanks bud.

ATX-Iroc

do you do any tuning? You can adjust the fan to turn on anyime through the computer but there only a few different fan swithces. It not any harder to fix it either, gotta be the computer or the sensor or motor, all very easy to figure out

camaronewbie

As far as I've always understood it ...

Single fan cars were controlled by the fan switch in the pass side head.

Dual fans cars were controlled primarily by the ECM and it got it's info from the coolant temp sensor in the thermostat housing - usually turning primary fan on at about 220. Secondary control was from the fan switch in the pass head that was set at 238. TPI cars were all dual fan I thought, but...

Yours is not - So, a TPI motor with a single fan I'm confused on, since I didn't know such existed.

BUT - if all else fails, you can rig the fan solely to the fan switch in the pass head, like the TBI cars were, and get a fan switch for whatever temp you like (within reason). Just because the ECM was programmed to turn on the fan at a certain temp doesn't mean that it's going to freak out if it doesn't actually turn on the fan, since it doesn't know. It just bases it's fuel mixtures and timing tables off the temp reading it's getting regardless of 'how' the fan was turned on. This would be the easiest last alternative since you wouldn't have to do any reprogramming of the chip, just rig the fan, it's relay, and a fan switch - I'd use a 210-220 temp switch - that should keep the car warm enough to keep the ECM happy but keep the engine temps down a tad.

Hope that makes sense. Might not help, but hope it at least makes sense.

Chevy86 IROC-Z

iTrader: (17)

Yup. Mine is a 86 IROC "VIN F" with a out of factory single fan. To answer a few previous questions, the fan works, the ECM is a Reman from Autozone (6 months old) and no temp switch. I have the fan hooked up with a relay that turns on my fan key the key is turned on. But I don't want premature failure on my fan. So that's why I asked about which is better, ECM or Temp switch. I tried hooking up to the ECM control ( which has a programmable EPROM that was burnt from a fellow TGO member) and the fan wouldn't turn on after warming up to 200* so I called my buddy to verify at what temp he set the turn on. He told me the turn on is at 190* and turn off @ 183* . So I'm gonna wait till the rain stops and retest with a multi meter and laser thermometer. Then I may check the continuity of the ECM wire at its origin, to the battery area.

henryd3

iTrader: (128)

Yeah, there were lots of 305 TPI cars with the same single fan system as the TBI's. Your vin "F" indicates it came originally as a 305 engined car.

Chevy86 IROC-Z

iTrader: (17)

Yup. Which verifies that my IROC has a single fan due to the 305 it once had. Not very many people know that the only option for a for for the 86 IROC was a 305. It wasn't till the 87 IROC that carried the dual fan, 350 block.

henryd3

iTrader: (128)

Well, of your two options,if you do have an ECM that has the fan turn on potential, the temp they usually are set to come on is lower than where the stock fan switch turns them on so that might be good for you. Changing anything about the temp requires chip burning, but if you can do that it may be more reliable than the notoriously high fail rate of fan switches. Both trigger the relay the same way, so everything after that is the same either way. The fan switch is a lot easier to swap out than burning a chip for many, and I think very few people have the option you have, so it kind of depends on what you want and what you are equipped and prepared to do to if there are any problems. I've had several different aftermarket fan switches fail in short time, but so far the AC Delco one(stock temp) I've got now has lasted the longest. No idea if that is using the best part or just wild luck. Not quite as hot around here, but not much worse than where you're at, but then I'm only driving a 5.0 and not all that much racing around either. Good luck with it, there are tons of threads about all this that start popping up after winter fades and everyone's car starts heating up. Do a search if you haven't already and check them out. Later

hellz_wings

iTrader: (2)

I had a single fan on my 86 when I bought it. I converted to a dual fan from a 1989 trans am and it never overheats anymore!

IROC212

iTrader: (1)

Did the exact same thing, my single fan couldn't keep up in our heat here (115+) in the summer.
I just recently upgraded to a flex a lite fan controller with adjustable temp control.

The factory single fan was triggered off the ecm, the right side head where the temp switch on the dual fan cars was plugged off.

camaronewbie

Those Flex-a-lite controllers are the greatest! Best $100 I ever spent!

Chevy86 IROC-Z

iTrader: (17)

A lot of good info here. Thanks guyz. Much appreciated.

darrlee

Here is another type/brand of after market controller I found. I'm thinking about ordering it since it comes with the head sensor rather than probe sensor. I'm not too cool with the idea of sticking a probe in my radiator fins like the others seem to come with.

Tell me what ya'll think?? Thanks!

http://www.jegs.com/i/Derale/259/16749/10002/-1

87IROC-DAN61

Hello Chevy86 IROC-Z!!

I too have the same set up as you, and I have a 1987 305 TPI single fan, no A/C Camaro!!

The factory set up was the ECM controls the fan turn on temp at 220*, but there was a redundant passenger side cylinder head fan switch that turned the fan on at 235* in the event of the ECM failure. Changing this fan switch to a lower temp switch will still not make the fan turn on any sooner, as it's still controlled by the ECM until 220*!!

One answer is to get the dual fan set up, and control one fan via the passenger side cylinder head fan switch!!

Another answer is to get the fan turn on temp reset via a new prom!!



P.S. I like these two methods, as it makes for a "factory" looking set up!!

hellz_wings

iTrader: (2)

I have the dual fan AND a PROM chip burnt for turn on at 180 degrees. Car stays in between 160 and 180 at all times.

darrlee

Hellz_wings,

How does your engine run keeping it below 180*? I've read many other post that indicate that the engine will run better if kept in the 195*-210* range....

Just looking for input from people that have tried both options. I too am leaning towards re-programming the ECM to keep the "stock" look and options.

Thanks for all the good info on here!!

hellz_wings

iTrader: (2)

I use AutoProm from MOates.net and the 6E code (1989 code) on my 86 MAF TPI 305. It's not a stock 305 at all. In fact everything has been changed. Internals, heads, cam, TPI all aftermarket, and every bolt on and little mod possible, etc.

With the Autoprom and Tunerpro you can reprogram basically anything in the ECM. I programmed it to run that way because I plan on increasing timing and I know that colder (to a certain point) is usually better for more timing.

I don't care about emissions and gas efficiency, which is what a hotter engine will be better for compared to a cold engine. But a colder engine wears out the parts less and has more performance, and mine idles a bit better when 160-180. Your results may vary.

I sometimes get into the 180's but that's about when the fan turns on and quickly brings it back down to near 160. The only problem I have is that my O2 sensor doesn't go into closed loop too often, but this is probably because I have headers because I got the engine to go up to 190 to test it and it only still went into closed loop sometimes. So it's probably a problem that lies elsewhere such as needing a 3-wire heated O2 sensor (already ordered from TPIPARTS.NET).

Other than that, I never had a problem and I don't think you will either. Since you live in Texas I imagine running 160-180 will be only a good thing! I live in Canada and summers here aren't nearly as warm as yours are!

Later,
-Marc

305sbc

iTrader: (3)

The ECM uses a green/white wire to send a ground signal to the fan relay to turn the fan on.

Key-on is a +12v signal.
Make sure you reconfigure your relay to activate with the ground signal from the ECM.

A temp-switch in the head can also be used to send a ground signal to the relay for fan activation. It is normally used as a back-up trigger.

Chevy86 IROC-Z

iTrader: (17)

Well the wire that is grounded (for the relay) is the one that I used to connect to the green/white wire. But after 5 minutes of idle, the fan never kicked on. I have yet to test the temp of the cooling system with a lazer thermometer. Hopefully ill have the time tomorrow.

rushtk

is there a way to test the ecm to verify it is the culprit for both fans to not turn on?