FEH and extreme cold climates-any issues?
#21
09-28-2009, 11:17 AM
Re: FEH and extreme cold climates-any issues?
Did we ever determine if pulling that fuse increases the mpg by any significant amount?
#22
09-28-2009, 11:49 AM
Re: FEH and extreme cold climates-any issues?
Last edited by wptski; 09-28-2009 at 11:55 AM.
#23
09-28-2009, 12:05 PM
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Re: FEH and extreme cold climates-any issues?
It's not 50% of voltage as that's not what PWM control is! It's 12V at a % of the time based on frequency and that being 1kH. Look at the waveform is this post: https://www.greenhybrid.com/discuss/...tml#post203066.
Sorry "my thinking" was that a voltmeter or A/D converter would read/display 6 volts for a 50% duty cycle.
The SG-II is reading the Ford PID for duty cycle on the ATC unit in the rearend.
But still, a reading of 50% voltage duty cycle might, or might not, indicate any significant level of coupling to the rear driveline.
That's why also there is a TSB #09-12-11 for 4WD Escape making a "hooting" like noise when leaving a dead stop. Reprograming of the 4WD module is supposed to somewhat "reduce" that noise. If the 4WD wasn't enabled then, there'd be no noise.
Sorry, IMMHO the dual clutch assembly might generate LOTS of "noise", maybe even harmonically elsewhere in the driveline, without coupling any significant level of torque. Think of a manual transmission with the clutch just ever so slightly engaged and a rising engine RPM.
I might add that when the fuse is pulled to disable the 4WD module, you can easily feel the difference!
Sorry "my thinking" was that a voltmeter or A/D converter would read/display 6 volts for a 50% duty cycle.
The SG-II is reading the Ford PID for duty cycle on the ATC unit in the rearend.
But still, a reading of 50% voltage duty cycle might, or might not, indicate any significant level of coupling to the rear driveline.
That's why also there is a TSB #09-12-11 for 4WD Escape making a "hooting" like noise when leaving a dead stop. Reprograming of the 4WD module is supposed to somewhat "reduce" that noise. If the 4WD wasn't enabled then, there'd be no noise.
Sorry, IMMHO the dual clutch assembly might generate LOTS of "noise", maybe even harmonically elsewhere in the driveline, without coupling any significant level of torque. Think of a manual transmission with the clutch just ever so slightly engaged and a rising engine RPM.
I might add that when the fuse is pulled to disable the 4WD module, you can easily feel the difference!
The Cessna 337 series had to have a special sensor system to advise the pilot that the rear engine/prop wasn't producing proper drive torque for this very reason.
#24
09-28-2009, 01:40 PM
Re: FEH and extreme cold climates-any issues?
My seat of the pants "sensor" is fairly highly calibrated, FLIGHT calibrated, and I still don't seem to be able to tell which end of the car the drive is "coming" from.
The Cessna 337 series had to have a special sensor system to advise the pilot that the rear engine/prop wasn't producing proper drive torque for this very reason.
The Cessna 337 series had to have a special sensor system to advise the pilot that the rear engine/prop wasn't producing proper drive torque for this very reason.
Another one is making sharp turns at <5MPH and that PID should read at least 20%.
#25
09-28-2009, 01:57 PM
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Re: FEH and extreme cold climates-any issues?
It's a Ford PID for 4WD duty cycle. For instance, a pinpoint test from the shop manual instructs the tech to command 100% rear wheel torque and if the vehicle resists turning, it's functioning correctly.
Another one is making sharp turns at <5MPH and that PID should read at least 20%.
Another one is making sharp turns at <5MPH and that PID should read at least 20%.
Is the PID readout a percent of voltage duty-cycle or a percent of rear driveline coupling coefficient...??
With sharp turns at <5MPH on dry pavement there shouldn't be ANY coupling to the rear driveline so I suspect the 20% is only a voltage duty-cycle level, a "keep-a-live" voltage, and NOT a direct indication of drive coupling.
What's the PID supposed to be with the brakes applied..??
Rear coupling should very definitely be ZERO in that situation, especially so with the OAT at or near freezing.
Last edited by wwest; 09-28-2009 at 02:00 PM.
#26
09-28-2009, 03:24 PM
Re: FEH and extreme cold climates-any issues?
Hmmm...
Is the PID readout a percent of voltage duty-cycle or a percent of rear driveline coupling coefficient...??
With sharp turns at <5MPH on dry pavement there shouldn't be ANY coupling to the rear driveline so I suspect the 20% is only a voltage duty-cycle level, a "keep-a-live" voltage, and NOT a direct indication of drive coupling.
What's the PID supposed to be with the brakes applied..??
Rear coupling should very definitely be ZERO in that situation, especially so with the OAT at or near freezing.
Is the PID readout a percent of voltage duty-cycle or a percent of rear driveline coupling coefficient...??
With sharp turns at <5MPH on dry pavement there shouldn't be ANY coupling to the rear driveline so I suspect the 20% is only a voltage duty-cycle level, a "keep-a-live" voltage, and NOT a direct indication of drive coupling.
What's the PID supposed to be with the brakes applied..??
Rear coupling should very definitely be ZERO in that situation, especially so with the OAT at or near freezing.
That's the pinpoint test for a noise or binding, if you see over 20%, it's normal. Going in a straight line I can't touch the throttle without showing over 20%!
They don't list any other situations and I've even ask at the dealer who called their Tech HotLine. No specs are available for any other situation. Brakes ON is no throttle, so it shows 0% and the same at a steady speed. Pedal to the metal from a dead stop, never seen more than about 30%.
#27
09-28-2009, 04:12 PM
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Re: FEH and extreme cold climates-any issues?
20% coupling coefficient when travelling in a straight line on a highly tractive surface, say for hour upon hour, would, IMMHO, generate so much stress and heat on the drive train that some part would soon fail.
On the other hand only 30% with WOT from a dead stop seems inordinantly LOW.
Maybe the 30% goes up as OAT approaches freezing..??
The more I read about the FEH's F/awd functionality the more I'm convinced that the REMCO (remcotowing.com) halfshaft coupling/de-coupling should be used to disengage the front drive under normal conditions while supplying a SOLID 12 volts to the rear driveline clutch.
A part-time R/awd system, only engage, manually, the front drive in actual poor tractive conditions.
On the other hand only 30% with WOT from a dead stop seems inordinantly LOW.
Maybe the 30% goes up as OAT approaches freezing..??
The more I read about the FEH's F/awd functionality the more I'm convinced that the REMCO (remcotowing.com) halfshaft coupling/de-coupling should be used to disengage the front drive under normal conditions while supplying a SOLID 12 volts to the rear driveline clutch.
A part-time R/awd system, only engage, manually, the front drive in actual poor tractive conditions.
#28
09-28-2009, 04:16 PM
Re: FEH and extreme cold climates-any issues?
The FEH 4WD feature is programmed to engage the rear axle
when “slip” is detected between the axles. Unless someone has
downloaded the software and decompiled it so that they can
read the criteria, we are only guessing.
Using the scangauge to infer how it operates is a good idea (and
playing “headsup ball”), but whatever we determine will remain
an educated guess.
when “slip” is detected between the axles. Unless someone has
downloaded the software and decompiled it so that they can
read the criteria, we are only guessing.
Using the scangauge to infer how it operates is a good idea (and
playing “headsup ball”), but whatever we determine will remain
an educated guess.
#29
09-28-2009, 04:19 PM
Re: FEH and extreme cold climates-any issues?
The FEH 4WD feature is programmed to engage the rear axle
when “slip” is detected between the axles. Unless someone has
downloaded the software and decompiled it so that they can
read the criteria, we are only guessing.
Using the scangauge to infer how it operates is a good idea (and
playing “headsup ball”), but whatever we determine will remain
an educated guess.
when “slip” is detected between the axles. Unless someone has
downloaded the software and decompiled it so that they can
read the criteria, we are only guessing.
Using the scangauge to infer how it operates is a good idea (and
playing “headsup ball”), but whatever we determine will remain
an educated guess.
For myself, I know that I did not like the FWD and did like the AWD. They performed significantly different on my test drives.
#30
09-28-2009, 04:33 PM
Re: FEH and extreme cold climates-any issues?
Stevedebi: I used “slip” in a more generic sense. My manual (an 06) speaks of slip I believe…
But what you spoke of is certainly in the realm of what I was thinking… And I am sure Ford would include programming that improved performance!
I was just trying to cut off the other BS being put up. The issue is how is the darn thing programmed and a few people think they have the ultimate answer just because…
But what you spoke of is certainly in the realm of what I was thinking… And I am sure Ford would include programming that improved performance!
I was just trying to cut off the other BS being put up. The issue is how is the darn thing programmed and a few people think they have the ultimate answer just because…
