I’m guessing it’s the CHT sensor input
voltage scaled to yield temperatures
for some Ford vehicles?

The working CHT pid might need to be
edited to remove the +32 as reported
by others. (Mustang).

((A*256)+B)/13168 for voltage?

13000 = 3.513 Volts
12000 = 3.243 Volts
5000 = 0.380 Volts

There is a 7.3 OBS thread which shows an example
of scaling voltages to temperatures. The 7.3 IAT
voltage would decrease with higher actual temps
and around ~4 volts at freezing. Similar to what
you are describing.

http://torque-bhp.com/forums/?wpforumaction=viewtopic&t=3903.0

Its probably not a linear response… for
grins I would try the IAT and TFT poly
equations listed near page 9-10 of the
7.3 thread. Maybe the 7.3 uses the same
sensor part as your vehicle?

Remember your PCM is reading the sensor
voltage (input), converting it and sending out as
a temperature pid (output). The voltage signal is
probably looking like a stretched “S” with a
tilt if you plotted it over its full range.

I’m thinking it is your CHT sensor voltage. If
you create a custom pid using the equation
for voltage, you will likely see the values
change in sync with your CHT temperature pid.

I believe it is the CHT sensor input.

for example…

0.35 volts ~ 230 °F
3.51 volts ~ 50 °F

on older ECT/IAT sensors based upon
service manual check points.

Your observed data for CHT Temp pid (output)
cold and at temperature seems to agree
with these numbers.

In short, I believe that the CHT alt pid is
reading in voltage and the linear equation
in Torque was for a different sensor type
on another Ford product.

Remember, I also believe your CHT temp pid
is reading high by +32 °F. Subtracting 32 °F
would more closely match your coolant
temperatures.

At the ends of the voltage “S” very little voltage
change equates to larger temperature changes.
241 °F is near one end of the “S”.

Edit:

Your observed data at cold and hot temps
seemed reasonable but your screenshot with
12720 at 241°F does not? I thought you were
seeing around 5000 at running temps.

@ Capp777, or other members:

I have found out that on my vehicle (2004 F150 5.4L 3v), the PID 221685 is the PCM control output to the “Charge Motion Control Valve” (CMCV, a/k/a IMRCV “Intake Manifold Runner Control Valve)

I found a vacuum leak (cracked intake manifold) – thanks to Torque by monitoring O2 sensors while I sprayed starting fluid around / under the intake manifold. The manifold has an electrically operated actuator mounted on its rear – between the engine and firewall – with linkage and butterfly plates in each intake port operated by mechanical linkage.

The readings the Torque App shows as ‘Cyl Head Temp (alt)’ in degrees F, is actually a 0 to 100% OPEN of the CMCV manifold port plates. [ note the reading descriptions of my original post — “range all over the place from 5000 to 13000”)

I do not know _exactly_ what the range extremes are, OR what the present Torque formula output relates to. But with the new manifold / CMCV valve installed and the truck running beautifully, I can definitely tell the PID is for that valve, and is commanded by the PCM depending on “cold” operation (2500 reading) and increases (to 13190 reading) on increased RPM or heavy load at midrange RPM.

Can you or any member provide some guidance or advise me how I can come up with a proper formula to make a display read Zero to 100% based on this PID [221685] for the CMCV or IMRC?

TIA F150Torqued

———–

54371019

@Capp777, or other Member(s);

Thanks for your prompt reply Capp777 – and your formula was instrumental in making the schema “CLICK” in my head. [it was the 655.35 that did it — as an old assembly code programmer, I recognize that number all too well], and now that I am armed with what we are doing, I’ve learned more by taking the following steps.

First: I tried your formula(s) and the Torque gauge I created & assigned made no sense.

Second: recognizing that your formula essentially just zeros byte “A” and adds byte “B”, then multiplies that by the reciprocal of binary 65535 / 100, I did the following to take a closer look at the data I’m working with.

Third: I removed the second half of the formula ” *(1 / 655.35)”. Then set up a log file logging Engine RPM, MAF, Speed, and the ‘raw value’ of this elusive CHTMP(alt) signal every 5 seconds over a 25 mile trip.

Fourth: I imported the log file into EXCEL and converted the CHTMP(alt) into a 16 bit binary field with excel. ((See the screen capture below)) Judging by the changes in bit patterns, I believe the binary field is comprised of more than ONE signal, and even perhaps a flag bit or two.

I know that my vehicle (2004 F150 5.4L 3v) DOES have a CMCV. However, it is still an assumption that this OBD2 signal has anything to do with driving that charge motion control valve. But if it does, perhaps this signal is a position command (ie represents a stepping motor command) and perhaps a “feedback” signal combined in part of byte “B”. The CMCV does have 4 pins, so it would be capable of providing feedback as to its position. I have to keep in mind this signal I’m looking at is coming from the PCM – and not the device.

NEXT: I plan to try to parse byte two and see if I can find bits that represent FLAG bits, and any that are nibbles containing binary values that could be represented on a CMCV % open/closed gauge on Torque. Any ideas or information you (or ANYONE) can spot in the following binary representation would be helpful.

Thanks. F150Torqued

———–

54371019

@Capp777, first allow me the privilege to say — you were right from the very beginning. PID 221685 on my ’04 F150 5.4 Triton IS IN FACT Cylinder Head Temperature (alt) – just like Torque Pro labels it and like you said in your first reply.

As often happens, a clue was staring me in the face. The screenshot in my second post shows CHTMP [241.9 ºF] and CHTMP(alt) [12,720 ºF] and both are setting at approximately the same percentage scale.!!! (although overall CHTMP(alt) never made sense).

Capp777’s FIRST response to my post was largely dead on correct about being a voltage representation — but I learned the Cyl Head Temp is a sophisticated DUAL thermister type sensor (both hot & cold range sensors) with only two conductors and one common ground via the Cyl head. The PCM uses a complex algorithm to determine Cyl Head Temp – and from that extrapolate coolant temp. The 5.4L Triton engine has no coolant temp sensor. The PCM outputs an ECT PID, and two PID’s, 221624 and 221685 for CHT, all from this single sensor. A very informative article on FORD CYL HEAD TEMP SENSORS exists at http://www.searchautoparts.com/motorage/powertrain-pro/diagnosing-fords-cylinder-head-temperature-cht-sensor

The standard Torque formula for PID 221624 (CHTMP) (((A*256)+B)*1.999)+32 displays ºF perfectly. IMHO the “+32” should be there, likely for ºC to ºF offset. Also I believe CHTMP *should* be somewhat higher than my coolant temp.

HOWEVER, sorting out PID 221685 — has been a different story and almost drove me NUTS before finding the article in the above link. As it turns out – Capp777 was dead on correct again – with _minor_ adjustments. WHAT the PCM is doing with PID 221685 is fascinating to say the least. In trying to sort it out, I Analyzed the pure untouched output of PID 221685 [by using the simple formula (A*256)+B], and converted that value to 16 bit base 2 using Excel.

WHAT I FOUND WAS FACINATING – INTERESTING – and clever. The 16 bit word consisting of bytes “A” and “B” is broken into two very odd sized nibbles. The LSB 6 bits are a signed value of +32 to -32 (total of 64). The next 9 most significant bits are a non-signed value between 0 to 512. These two nibbles independently, synchronously, and uniformly track the temperature. The MSB is a switch (I think 1 indicates the LSB 15 bits is voltage for “hot” range circuit, and 0 indicates the voltage reading represents the “cold” range circuit – see the linked article), but that’s not important here.

What is important is at FULL EOT the high order bit is always ON, and if the two weird size nibbles are viewed purely as a 16 bit “word” value, applying the formula Capp777 provided for 0-5v conversion, [ ((A*256)+B)/13168 ], and the result is displayed on a 0-5 volt gauge in Torque, it tracks CHTMP.

On a cold soak startup, the PCM goes through an apparent “calibration” procedure that takes about 10 minutes during engine warm-up. (This action can somewhat be seen in my previous Excel Screenshot) These two nibbles, each independently, but synchronously, perform a binary count down – starting from value at the end of last drive cycle, counting down to binary Zero — that (not so surprisingly) represents .5 volts (which would be the voltage drop across a silicon junction in the PCM substrate where it would cease conducting current). Also the count of 256 in the upper nibble (with a zero in the lower nibble) equates to exactly 2.5 volts. What is interesting (and clever) about this is – when you view the whole word “A and B” as a binary value (where the lower 6 bits ranges from -31 to +32) as a integral part of that whole word, it creates a perfect “S” curve in the value being output by the PCM. Thus the PCM is taking care of the “S” curve calculations and making the output a pure clean 0-5v signal for the external reader. I thought that was kind of a slick way to do it.

But, now I do not know the proper PID for my “Intake Charge Motion Control Valve”, which is what I thought 221685 was.!!! I’ve tested the 221684 that Capp777 suggested, but it returns “NO RESPONSE”. ????? There is a DTC for “IMCV stuck OPEN” and “IMCV stuck CLOSED”. Does Anyone know what PID would read the condition or position of the IMCV on a Ford 5.4L engine?

Thanks for help.

—————

54371019