TBI inj computer , does it control turning on and off electric fans ?

[67cheby]

i will be running a TBI computer, i am just trying to figure out if i need to buy a seperate controller for my electric fans or does the stock computer turn the fans on and off ? anyone know ?

[spatz]

We need more information, Is it a original factory set up with or w/o electric fans or an after market setup?

[MARKDTN]

Pretty sure the F-body ones and B-body ones can. Not sure about the truck ECMs though. You best bet would be to talk to the chip builders/harness makers like Howell, Street and Performance, etc.

[406 Q-ship]

The fans on both any of the TBI's is more of a protections system that does not come on until the engine reaches a temp of 230°. It is seperate from the PCM for the TBI. The operation of the A/C will run the fans, this as well is run on a seperate system from the TBI computer.

It wasn't till much later vehicles that the fan controls were installed in the PCM.

[67cheby]

406 Q-ship, do you have a suggestion on what system i should run to control my fans ?

[67cheby]

oh and it is a truck ecm, and the wiring harness is aftermarket from (fuelinjectionconnection.com)

[frednoah]

I'd suggest a Spal PWM setup like the one here. They are around $150 or so I think, but they have a ton of cool features.

If running dual fans, you'll also need a fan relay harness. I think you can find it cheaper, but here is the link for comparison's sake.

The guys on Chevytalk loved this setup with dual Spal fans in the tri-five Chevys when I was working on my 56.

[67cheby]

i just snatched one of these up BARGAIN !!! there is 4 left !http://www.ebay.com/itm/Spal-Fan-PWM...sories&vxp=mtr

[frednoah]

Make that 3... damn bargains get me every time.

[67cheby]

Lol ......it's a sickness I understand
Posted via Mobile Device

[MARKDTN]

Originally Posted by 406 Q-ship

The fans on both any of the TBI's is more of a protections system that does not come on until the engine reaches a temp of 230°. It is seperate from the PCM for the TBI. The operation of the A/C will run the fans, this as well is run on a seperate system from the TBI computer.

It wasn't till much later vehicles that the fan controls were installed in the PCM.

After a little research it turns out you are right for the TBI stuff. Wierd because TPI had fan control all along. There are "hacks" that you can do to give the 7747 ECM fan control though if you do a little research.

[Warrens69GMC]

The 7746 ECM used in camaro and firebirds do have the 230*turn on, but we TBI guys know we can use a Grand National rad fan switch that come on at 200*, off at 180*

[67cheby]

i am going to get out my ecm tonight and see which one it is

[406 Q-ship]

Originally Posted by MARKDTN

After a little research it turns out you are right for the TBI stuff. Wierd because TPI had fan control all along. There are "hacks" that you can do to give the 7747 ECM fan control though if you do a little research.

Alot of the TPI systems use the same seperate fan controls as the TBI's. As long as the vehicle moves through the air there is a no need for the fans to be running. Even when the fans are controlled by the PCM, they will try to hold the temp between 212-205°. This is for fuel economy and emissions. There are quite a few adjustable tempeture probe that can be spliced into the wiring running to the fan temp switch (this is only on the seperate fan system NOT the PCM controlled style). Don't go nuts on trying to get low engine temps with the fans, it is an old wives tale that an engine runs best at lowest temp possible. Too low of a temp will cost fuel economy and drivability issues. Run a 180° t-stat and turn the fans on at 210° and off at 190°.

[MARKDTN]

Originally Posted by 406 Q-ship

Alot of the TPI systems use the same seperate fan controls as the TBI's. As long as the vehicle moves through the air there is a no need for the fans to be running. Even when the fans are controlled by the PCM, they will try to hold the temp between 212-205°. This is for fuel economy and emissions. There are quite a few adjustable tempeture probe that can be spliced into the wiring running to the fan temp switch (this is only on the seperate fan system NOT the PCM controlled style). Don't go nuts on trying to get low engine temps with the fans, it is an old wives tale that an engine runs best at lowest temp possible. Too low of a temp will cost fuel economy and drivability issues. Run a 180° t-stat and turn the fans on at 210° and off at 190°.

I have used the 7730 ECMs on all my TPIs. The primary fan is controlled by the ECM through the coolant temp sensor in the front of the intake, the secondary fan is controlled by the switch in the head and/or high pressure switch in the A/C line on those. I do swap that 250 switch for a 230. I assumed that the TBI ECM would be similar but looks like it is not. I do agree on the temps. I run a 195 T-stat as GM discontinued the 180s years ago. 200 I used to think was horrible, now it is normal. The engine is actually more efficient at higher temps.

[67cheby]

got the SPAL unit in today

[piecesparts]

Originally Posted by frednoah

I'd suggest a Spal PWM setup like the one here. They are around $150 or so I think, but they have a ton of cool features.

If running dual fans, you'll also need a fan relay harness. I think you can find it cheaper, but here is the link for comparison's sake.

The guys on Chevytalk loved this setup with dual Spal fans in the tri-five Chevys when I was working on my 56.