added UD pulley's, need to change anything?

[Sburn]

Originally Posted by JackandJanet

I don't know what to check either. Sounds like the system thinks you have e-fans, but you don't show that you do. I don't think there's any kind of monitoring for the clutch driven fan.

- Jack

Ford changed stuff on the engine fans, starting ~2006 or 2007. Even though the fan is driven by the water pump pulley as before, the clutch is controlled by the PCM. And it appears to be more than just on/off control. Looks like the PCM outputs PWM (pulse-width moulation) which controls how much the clutch locks up, which in turn controls the actual speed of the fan. It's a closed loop system because the fan then has a sensor that reports its RPM back to the PCM. There's DTCs for when the PCM commands the fan clutch to engage and but doesn't see an increase in the reported fan speed.

[88Racing]

Originally Posted by Sburn

Ford changed stuff on the engine fans, starting ~2006 or 2007. Even though the fan is driven by the water pump pulley as before, the clutch is controlled by the PCM. And it appears to be more than just on/off control. Looks like the PCM outputs PWM (pulse-width moulation) which controls how much the clutch locks up, which in turn controls the actual speed of the fan. It's a closed loop system because the fan then has a sensor that reports its RPM back to the PCM. There's DTCs for when the PCM commands the fan clutch to engage and but doesn't see an increase in the reported fan speed.

Beat me to it!
Better description than what I had to offer!

Lars

[Jackpine]

Originally Posted by Sburn

Ford changed stuff on the engine fans, starting ~2006 or 2007. Even though the fan is driven by the water pump pulley as before, the clutch is controlled by the PCM. And it appears to be more than just on/off control. Looks like the PCM outputs PWM (pulse-width moulation) which controls how much the clutch locks up, which in turn controls the actual speed of the fan. It's a closed loop system because the fan then has a sensor that reports its RPM back to the PCM. There's DTCs for when the PCM commands the fan clutch to engage and but doesn't see an increase in the reported fan speed.

Sburn - you're an absolute goldmine of knowledge! (I'm being quite sincere when I say that).

Funny, isn't it, that something as simple as a temperature induced viscosity increaser would have to be replaced by sensors, specialized circuitry in the PCM and probably, a much more complicated clutch mechanism in the fan hub. I suppose that's progress, and I'm sure it's ever so much more precise, but still....

- Jack

[Sburn]

Originally Posted by JackandJanet

Sburn - you're an absolute goldmine of knowledge! (I'm being quite sincere when I say that).

Thank you. I claim no special abilities other than I enjoy reading wiring diagrams and powertrain manuals and such.

Funny, isn't it, that something as simple as a temperature induced viscosity increaser would have to be replaced by sensors, specialized circuitry in the PCM and probably, a much more complicated clutch mechanism in the fan hub. I suppose that's progress, and I'm sure it's ever so much more precise, but still....

- Jack

I can make a guess why Ford ended up with such an elaborate system: R-134 refrigerant in the A/C just doesn't work as good as the older R-12 at idle/slow speeds, so you really need the fan to be engaged and pulling fresh air through the condenser when the vehicle is moving slowly. But, at highway speeds, the fan doesn't even need to be there at all to provide A/C and engine cooling and becomes a load that hurts mileage. Being that the PCM already knows the vehicle speed, ambient temp, A/C status, engine temp, etc. anyway, it makes sense to spend a few extra bucks for some wires, connectors, and a few lines of CPU code to eliminate the above two issues. And since it's all just softwre at that point, might as well do something smarter than just On/Off controll and have the PCM map the perfect fan RPM against temps, A/C, VSS, engine temps, etc.. And after replacing one or two of the older visco/thermo -style clutches in my time, I can see how having the PCM know about a misbehaving clutch would be a good thing.

[Jackpine]

Originally Posted by Sburn

Thank you. I claim no special abilities other than I enjoy reading wiring diagrams and powertrain manuals and such.




I can make a guess why Ford ended up with such an elaborate system: R-134 refrigerant in the A/C just doesn't work as good as the older R-12 at idle/slow speeds, so you really need the fan to be engaged and pulling fresh air through the condenser when the vehicle is moving slowly. But, at highway speeds, the fan doesn't even need to be there at all to provide A/C and engine cooling and becomes a load that hurts mileage. Being that the PCM already knows the vehicle speed, ambient temp, A/C status, engine temp, etc. anyway, it makes sense to spend a few extra bucks for some wires, connectors, and a few lines of CPU code to eliminate the above two issues. And since it's all just softwre at that point, might as well do something smarter than just On/Off controll and have the PCM map the perfect fan RPM against temps, A/C, VSS, engine temps, etc.. And after replacing one or two of the older visco/thermo -style clutches in my time, I can see how having the PCM know about a misbehaving clutch would be a good thing.

Oh, I think you're being a bit modest. You seem to understand and make inferences from what you read too. Not everyone can do that.

The part I "bolded" in your quote seems to make a case against e-fans, doesn't it? An intelligent fan that puts little to no drag on the engine at highway speed, but that runs (through a direct couple) when the engine is at idle to keep everything cool. Some people forget that the power for e-fans HAS to come from somewhere, and that "somewhere" is the alternator that is powered by the engine. Anytime you increase the load on the alternator, you MUST increase drag on the engine. And, since there is a "middleman", sort of, in this system (the alternator), you cannot have 100% transference of power to the fans, since nothing is 100% efficient.

And, to the th3godf4th3r (and everyone else), sorry that I hijacked this thread. It's one of my great failings. :o

- Jack

[Sburn]

Originally Posted by JackandJanet

Some people forget that the power for e-fans HAS to come from somewhere, and that "somewhere" is the alternator that is powered by the engine. Anytime you increase the load on the alternator, you MUST increase drag on the engine. And, since there is a "middleman", sort of, in this system (the alternator), you cannot have 100% transference of power to the fans, since nothing is 100% efficient.
- Jack

OK, to noodle the e-fan business around a little bit more, here are my thoughts and calculations. Feel free to refute, correct, debate:

Looks like the standard twin e-fan set-up (Spal, Derale, F-A-L) makes 4000-5000 CFM and take around 50 Amps (2 fans @ 25A). 50 Amps @ 12 Volts is 600 Watts. 600 Watts converts to 0.8 Horsepower. As Jack said above, there will be some conversion losses. A quick search suggests that belt-driven alternators are not much more than 50% efficient in converting mechanical to electrical power, so the engine has to turn the alternator with 1.6 HP to get that 0.8 HP (600W) out the other side.

I can find very little on how much HP is required to turn a conventional (non e-fan), other than from the folks who are selling e-fans. The often quoted 10-15 HP drag may come from a clutch-engaged fan at 5000 RPM for all I know. And the HP "savings" in that case would be 15 HP less the 1.6 HP for e-fans, in the case of the e-fans fans running full speed.


So, back to the real world:

In summer stop-and-go traffic, the e-fan may prove helpful with the added airflow for the A/C. 1.8 HP gets used to power those e-fans, but I'm not sure I care too much about losing 1.8 HP in stop-and-go traffic anyway. Having the A/C work real well is a fair trade on a hot summer day for me. The conventional fan in this situation is engaged and eating some ammount of HP, but it's likely moving less air than the e-fan, so it's likely using less HP than the e-fan.

Now, traffic clears out and I'm now zooming along at 60 MPH. e-fan are (or should be) completely off and taking zero HP. Conventional fan should have the clutch open and be freewheeling.

So at idle, the conventional fan may win the HP battle, provided you don't care about maximum A/C. And a 60 MPH, the e-fan wins since they should be off. At 60 MPH the conventional fan is disengaged, but it's still taking some HP just becasue of the mass and clutch drag.

Thoughts? Comments?

[Jackpine]

Full on, Sburn! VERY well presented post! It's what I like about this forum, people actually have brains over here and they use them!

I'm glad you did the research on the power loss, since I was too lazy/incompetent to do so. And it gives me a platform to comment.

IF, the 1.6 HP penalty is correct, and it sounds pretty good to me given the power demand figure you quote for the e-fans, then stopped at idle, it's kind of a "wash" isn't it? The e-fans are using a constant 1.6 HP, and the new PCM controlled fan's needs vary between quite low (at engine idle, since it is not turning very fast) to higher at cruising speeds - where it should be freewheeling anyway.

Now, the only thing that power demand does at idle is use a bit more fuel (in both cases) and, for the amount of time we're usually stopped, I doubt we'll feel much difference in the AC. So, the PCM controlled fan may win out in economy at idle and not make us too uncomfortable.

But, I don't know when the e-fan controller cuts it off as speed increases. I think it is purely temperature controlled, so it's possible the PCM controlled fan might cut off sooner, as a speed increase is seen?

And, since both should usually be off at highway speeds, we're left with your final statement. Is there any clutch drag with the new fan? The ram airflow through the radiator is going to encounter both kinds of fans and will try to spin them and all of this causes aerodynamic drag. But, the drag would be there anyway, since the engine and engine bay is not exactly a "slippery" aerodynamic shape. So, we spin the e-fans by airflow and get nothing in return since they are "decoupled". We spin the "water pump" fan and, if there is any clutch drag at all, we decrease its drag on engine power. But, if there's no clutch drag (does there have to be?) there's actually no power loss to the engine.

I know there was always some power loss through the fluid clutch since it is always ON. But, could the new clutch be purely (or effectively) mechanical? I doubt the new design would have been adopted if there were no real benefits. The fluid coupled fan was "simple", and it worked, but there was always drag. Maybe the drag was eliminated in the new, more complicated design?

- Jack

[Sburn]

Originally Posted by JackandJanet

Now, the only thing that power demand does at idle is use a bit more fuel (in both cases) and, for the amount of time we're usually stopped, I doubt we'll feel much difference in the AC. So, the PCM controlled fan may win out in economy at idle and not make us too uncomfortable.

But, I don't know when the e-fan controller cuts it off as speed increases. I think it is purely temperature controlled, so it's possible the PCM controlled fan might cut off sooner, as a speed increase is seen?

There's two flavors of e-fan controllers that I know of. Simple Off/On at a preset temprature (~thermostat temp) and PWM e-fan controllers that vary the e-fan speed based on the temp. sensed at either the radiator or by piggybacking on the factory ECT/CHT. So, the e-fan with a smart controller wouldn't always have to be running at 100% when it's on.

I know there was always some power loss through the fluid clutch since it is always ON. But, could the new clutch be purely (or effectively) mechanical? I doubt the new design would have been adopted if there were no real benefits. The fluid coupled fan was "simple", and it worked, but there was always drag. Maybe the drag was eliminated in the new, more complicated design?

- Jack

I'm not yet sure how the clutch works on the new PCM fans. Could be a PWM to some kind of solenoid that squishes some hydraulic bits, or a variable DC voltage to a magnetic particle clutch. I'll have to RTFM this weekend. Or, drag out the old oscilloscope.

Ford's PID show the fan RPM sensor and PCM output to the clutch as a percentage, but I don't yet know if the percentage mean duty cycle or a voltage: