PWM radiator fan controller

[parsonsj]

Finally.

I bought a salvage yard E67 off a V6 Malibu, sent it to a fellow in Austin TX who flashed a 2013 ZR1 OS on it, picked up a special copy of HP Tuners (2.25.xxx, still in beta), and copied my tune from the crate motor tune, and wrote the calibration out.

Voila, pwm fans.

Finally.

Geez, what a bunch of walls to knock down!

Net: The GMPP crate motor E67 OS does not and can not support PWM fans or AC pressure sensors. You have to use a late model passenger car E67 or E38 and OS, and deal with all the extra equipment implied in that. I've got a bunch of work left to delete all the DTCs that don't apply, plus puzzle out all the differences in the tuning tables.

[parsonsj]

A postscript:

Yesterday, I transferred the tune from the old GMPP file to the new ZR1 OS tune file. I moved every single table, one by one, and did a complete audit of all the DTC codes and their behaviors. The end result was unexpected, in a good way.

I finally fired up the car, monitoring all the usual parameters, including fan desired/fan %/AC pressure.

With an identical tune (as near as I can tell) the car runs better. The idle is smoother, throttle response is better, TPS % at idle is better (27% to 19%), fuel trims are markedly improved, and O2 voltages are smoother.

There's no doubt the car runs better with the ZR1 OS than with the GMPP OS, with an identical tune. Oh, and the fans function perfectly. AC and ECT desired both work exactly as documented.

Anyway, after 4 weeks' delay, the project is back on track. I'll never use a GMPP crate controller or OS again. From now on, I'll make my own harness, and get my own controller.

[TBART70]

Found out that the time delay relay needs to have 12 volts going through the accessory side to work. I will have to put a high amp relay in and use the time delay to control it. I wanted it to control the sensor but it has 5 volt reference which is not enough to power the capacitor.

Got it all together and it works good. 90 second delay off on the fans when car is off. pwm works well no full blast on the fans unless I hit the bypass switch.

[Red67Mustang]

pwm works well no full blast on the fans unless I hit the bypass switch.

So the fans won't run at 100% via PWM at all?

I've been following this thread to make this mod on my 67 Mustang with HP EFI, but was curious to know if the max of 90% duty cycle would result in full on for the fans. Ie; is the control module programmed such that output voltage is equal to input voltage at 90% duty cycle?

Has anyone ever tried to measure / test this?

Thanks!

[andrewb70]

So the fans won't run at 100% via pwm at all?

I've been following this thread to make this mod on my 67 Mustang with HP EFI, but was curious to know if the max of 90% duty cycle would result in full on for the fans. Ie; is the control module programmed such that output voltage is equal to input voltage at 90% duty cycle?

Has anyone ever tried to measure / test this?

Thanks!

I have no measured voltage to the fans at 90%, but it would be fairly easy to do. FWIW, my fan speed never even gets close to 90%. The highest I've seen it go is maybe 75% and that was after making a drag strip pass, shutting it off, having it heat soaking for 5 minutes, then starting it. Engine temp was around 210, give or take.

If I am idling for extended period of time, the engine temp is maintained to within 3 degrees (between 192 and 195 degrees), with the fan cycling to about 40%. I also have mine configured to not engage the fan at all at speeds above 30MPH, unless temp goes above 198 degrees (which it never does). My radiator was from Speedway and it cost 130 bucks. Aluminum, generic fitment, made in China no doubt.

I really see no issue with not being able to go to 100%.

[TBART70]

The Derale pwm works off of temp sensor supplied with it not off anything in my Holley HP. If I knew about the C6 Corvette fan controller I probably would have gone that way with the HP. That might change in the future. The point of PWM is that the fans come on slowly and are constantly adjusting to conditions. The temp way is they come on at a set temp and off at a lower set temp at full speed, although my other controller that kept popping the breakers would turn on one fan then ramp up the other as needed.

[parsonsj]

A new / different question:

Anybody know the relative difference in torque consumption by the Sanden compressor vs a C6 factory variable displacement compressor? There's a table referencing AC compressor torque consumption vs AC pressure. I'm wondering if I need to adjust the table to compensate for the Sanden taking more engine torque to run.

Anybody got a clue?

[old66tiger]

John...Interesting...has anyone responded or have you done any experimenting?

A new / different question:

Anybody know the relative difference in torque consumption by the Sanden compressor vs a C6 factory variable displacement compressor? There's a table referencing AC compressor torque consumption vs AC pressure. I'm wondering if I need to adjust the table to compensate for the Sanden taking more engine torque to run.

Anybody got a clue?

[parsonsj]

No.. no real response other than that the big V8 won't be bothered much by the little A/C compressor.

I added 20% to the table and called it good. I chased down a stall with this change plus some additional idle air.

[old66tiger]

My engine cares when the AC is on. It has the ASA cam so it may not like additional load at idle. When I get back to tuning in the spring, I may give you a call to discuss some of the things you were able to work out.

No.. no real response other than that the big V8 won't be bothered much by the little A/C compressor.

I added 20% to the table and called it good. I chased down a stall with this change plus some additional idle air.

[parsonsj]

When I get back to tuning in the spring, I may give you a call to discuss some of the things you were able to work out.

I look forward to it!

[David Pozzi]

90% max, eh? Good tip!

My approach is to get all this working with the C6 controllers, and go to a solid state relay if those controllers fail.

I've been researching pwm for use on my Camaro with Holley Dominator EFI. I'm trying to decide if I should use the Corvette unit or a Solid State Relay (SSR) Here are some info links:

Using Solid State Relays - SSR's: http://www.autospeed.com/cms/A_11051...popularArticle
http://www.autospeed.com/cms/article...elays&A=112737
Haltech wiring. With link to Haltech .pdf schematic http://forums.haltech.com/viewtopic.php?t=8090
More info on SSR's: http://www.phidgets.com/docs/Solid_S...Primer#DC_SSRs

I think a capacitor or capacitors on the load side of the SSR are needed to smooth out the square wave PWM pulses. https://www.youtube.com/watch?v=NQ08OztPkb8
The SSR needed is DC on both sides, the load it can carry depends a lot on if it's used with a heat sink. A 40 amp SSR can go to a 100 amp rating if used with a heat sink. It appears you want to size the SSR to be twice the capacity of the actual load, especially if you buy a cheap China version. There is no harm in using a 100A SSR for a car fan.

A diode across the load terminals shunts the fan motor spin-down load. It's mentioned in the Autospeed page.

The Haltech diagram shows a resistor around 50 ohms across the control terminals. Mentions "pull up" I read somewhere the SSR may not shut off due to a tiny amount of current flowing to ground through the ECM circuit. The resistors may help that, but I'm not sure why. I read that for Haltech use, the resistor isn't needed if the positive input is key switched off with the engine. That will stop the fan so the resistor must help with fan shut off.

[1989GTA]

Signing on to the thread. I am interested in doing this to my car. The problem with the Derale unit is that the fans continue to run for a while when the car is shut off.

[TBART70]

I have the Derale hooked up to a high amp relay, tripped by a timer relay for off. The Derale doesn't use a switched igntion, the relay does that for me (switched ignition). It is set for 90 seconds , it kills the power to it so they don't flutter on and off due to circulation.

[1989GTA]

I have the Derale hooked up to a high amp relay, tripped by a timer relay for off. The Derale doesn't use a switched igntion, the relay does that for me (switched ignition). It is set for 90 seconds , it kills the power to it so they don't flutter on and off due to circulation.

I was thinking of doing that. A year or so ago I sent Derale and email regarding that subject and the response I got back was that I was crazy and did not know what I was doing. I thought that was an interesting response. Where did you install the probe in the radiator?

[TBART70]

Funny thing about Derale, I broke off the a/c bypass post last year, I needed to finally get the a/c working. I purchased a new unit to replace the one I broke. I hooked it up last week and could not get it to work, a/c bypass or the actual pwm fans. I called and was told it was a voltage problem. I put in the old controller and they worked. Put back the new One and nothing. If I did not have a sensor bypass switch wired in, it would overheat. I adjusted the potentiometer as far as the voltage would go and it would not turn on. I called Derale and got someone else on the phone. He had me bypass the system and test with an ohmmeter the sensor from the old and new controller. He said according to the serial number the sensor I have in the car and the sensor in the box were wrong for the new controller. He is sending v me a new sensor and a noise filter. Goes to show you some people know what they are doing and don't assume you have no clue what is going on.



To answer your question. I had the sensor where they said to put it, the fans did not come on no matter what I did adjustment wise. I even tried heating the sensor, it did turn on then. I moved it to the hot side and it worked perfectly fine. It kept the temps reasonably good even in 90 + weather.

[1989GTA]

Thank you for the response. Actually putting it on the hot side does make some sense. I do have a dual pass radiator. One more question. What amperage relay did you use? Maybe a part number would be better. Thanks, Allen

[TBART70]

70 amp. I will look and see what the # is.

[andrewb70]

I've been researching pwm for use on my Camaro with Holley Dominator EFI. I'm trying to decide if I should use the Corvette unit or a Solid State Relay (SSR) Here are some info links:

Using Solid State Relays - SSR's: http://www.autospeed.com/cms/A_11051...popularArticle
http://www.autospeed.com/cms/article...elays&A=112737
Haltech wiring. With link to Haltech .pdf schematic http://forums.haltech.com/viewtopic.php?t=8090
More info on SSR's: http://www.phidgets.com/docs/Solid_S...Primer#DC_SSRs

I think a capacitor or capacitors on the load side of the SSR are needed to smooth out the square wave PWM pulses. https://www.youtube.com/watch?v=NQ08OztPkb8
The SSR needed is DC on both sides, the load it can carry depends a lot on if it's used with a heat sink. A 40 amp SSR can go to a 100 amp rating if used with a heat sink. It appears you want to size the SSR to be twice the capacity of the actual load, especially if you buy a cheap China version. There is no harm in using a 100A SSR for a car fan.

A diode across the load terminals shunts the fan motor spin-down load. It's mentioned in the Autospeed page.

The Haltech diagram shows a resistor around 50 ohms across the control terminals. Mentions "pull up" I read somewhere the SSR may not shut off due to a tiny amount of current flowing to ground through the ECM circuit. The resistors may help that, but I'm not sure why. I read that for Haltech use, the resistor isn't needed if the positive input is key switched off with the engine. That will stop the fan so the resistor must help with fan shut off.

David,

Hopefully you installed a C6 fan controller and called it a day. It works perfectly with the Dominator ECU.

If anyone cares, the Dormant version of the C6 fan is currently 69 bucks on amazon prime.

Andrew

[TBART70]

I would recommend going with the C6 setup if you haven't bought anything yet,as long as you have a computer capable of controlling it.

I like the Derale, but I am not happy how much lack of room there is to wire it, and to get to the adjustment, it is impossible to adjust when the car is running.