At what temp should my secondary fan come on? I have a PR chip (see sig) would that effect it at all?

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End with 2.77:1 Gears.

Current Mods: LT4 HOT Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Catco 3" High-Flow Catalytic Converter, Hooker 3" Aerochamber Cat-Back System, Transgo Shift Kit, Performance Resource Chip, Accel Ignition, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET: 14.32 @ 97.7mph
(corrected for elevation)

 

While there is SOME code in the eprom for the #2 Fan, NOTHING in the ecm itself can turn on #2 on its own. Trust me, I have FORCED the ecm to turn on #2 by itself, and even though I get a signal from the ecm to turn on #2, #2 WILL NOT come on. You have to replace the "Fan Temp Sensor" in the passenger side head to turn on #2.

I have toyed with the idea of "bypassing" the Fan Temp Switch so the ecm CAN control #2, but I haven't gotten around to it. It is theoretically possible...just haven't done it in the "real world".

 

So I have to buy one of those Hypertech fan switchs that costs like $45? That's pretty crappy!

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End with 2.77:1 Gears.

Current Mods: LT4 HOT Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Catco 3" High-Flow Catalytic Converter, Hooker 3" Aerochamber Cat-Back System, Transgo Shift Kit, Performance Resource Chip, Accel Ignition, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET: 14.32 @ 97.7mph
(corrected for elevation)

 

Go to a Napa and get a fan switch for an '87 turbo Buick. It has to be the 3.8 V6 Turbo. The fan switch will come on at 203 degrees and go off at around 193 degrees. It only costs about $25 compared to the Hypertech switch which is like $45 plus $8 shipping/handling.

 

Glenn,

I'm not sure if this applies to your car, but on earlier cars there are two parameter for controling secondary fan on/off functions.

1. Coolant temp - stock is 239° though the fan is not kept "on" constantly.
2. A/C press - anytime a/c press is detected as "hi", the secondary is activated and kept active.

 

More corrections>>>

For 1987, the secondary fan was controlled exclusively by the fan switch located in the passenger side head. There is no interaction between the fan and the ECM or A/C.

In addition, the secondary fan switch turns the fan on at an incredibly high 243 degrees (1987).

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Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
Former Paxton (6-psig): 12.57 @ 111 mph.
Former Paxton (6-psig) & former 50-hp nitrous: 12.04 @ 114 mph.
ATI D1SC (8-psig): 12.06 @ 115.94 mph.
Future ATI D1SC (?-psig): Gotta catch them pesky 26-psig boosted TTA's!!

http://willie.camaro-firebird.org/

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.

[This message has been edited by Willie (edited July 04, 2001).]

 

88, the A/C High Pressure switch is the code that I turned off to force the ecm to "try" to turn on Fan#2. As I said, on my car the ecm SAYS it is turning on Fan#2, but the wiring does not allow the ecm to control fan #2. As Willie said, only the Temp Fan Switch in the head will turn it on.

 

You can always run a simple flip switch to ground.

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Black 90 IROC, L98, A4, 323 gear. SuperRamed 406 in the works!

 

like mike said
just ground the wire coming off the pass side of the block at the coolant temp sensor. you may also have to ground a wire on the relay and both fans will come on at high only when the ignition is hot. i just leave my switch on (which i have put in the stock fog light switch) and the fans automatically come on and go off when you start or turn off the car.
Andrew

 

I thought about either linking both of the fans. DO NOT use one relay for both fans, this will just burn up the relay. What I thought might work is to link both of the relays together, so one signal turns on both fans.

The ECM controls that signal, so I am a little leary about going that route. So what I am thinking now is to get a third relay and when the ECM closes that connection to have the new relay pull on the two OEM relays.

just a thought

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87 Formula Yellow/Black
Engine & Transmission
.040 over 5.0 converted to TPI, 9.5:1 Compression, SLP Cam Dur 206/212, Lift 480/487, Cent Line 112, SLP headers, SLP cat-back exhaust, K&N Airfilter, Modified Stock cold air intake, Ported & polished Stock TPI intake, Holley Adjustable Fuel Press regulator, AC Rapidfire Spark Plugs.
Gil Younger (no yo-yo) Shift Kit, Aluminum Driveshaft, 3.73 Posi gear
Suspension & Brakes:
Baer 12" brakes 4 wheels, KYB AGX Adjustable Shocks & struts, Hotchkis strut tower brace, South side machine frame connectors, Custom reinforced control arms and pan hard bar.
Interior:
Custom Leather interior, CUSTOM Yellow Gauge Faces, Kenwood Receiver, Pioneer Speakers, Kicker Substations, Kenwood 10 Disk Changer, Pioneer Amp.

87 Formula TPI (5 Speed) Yellow/Gray STOCK

1967 Buick Riviera 430hp Turns high 14's (Not bad for 4300 lbs)

83 Camaro (Parts)
83 T/A (parts)

http://www.3rdgenformula.com