Heres the project:

Objective: Use the over heat protection funtion to shut down 1/2 the cylinders with tha flip of a switch for improved gas mileage.

Task:

1. Find out at what temp the over heat mode engages
   
2. find out what voltage or signal the Sending Unit is sending the ECM at that temp.
   
3. recreate that voltage or signal
   
   Then the easy one
   
4. put it on a switch

Don't try to tell me it cant be done because it is already built into our trucks. All we have to do is trick the trucks own program in to thinking that it is overheated when ever we want to on order to utilize this funtion to our own advantage. In theory 30+ mpg on the highway might not be out of the question for some. The hard part is that if we make it think that it is to hot then it will shut down. I figure with the group of great minds that we have assembled here if we work together we can figure this out and I'm not to scared to try out a logical theory on my own truck. So lets get this done.

 

This function is controled by the cylender head temp sender located in the drivers side cylender head under the intake although it is at the front area and reachable without removing the intake. It is a variable resistor with a range of appp .067 ohms being 500 degree f. to 965 ohms being -40 f Ther is a fail safe in the system for a short circuit to bypass the system incase it sees 0 ohms. there is a range that removes fuel to 4 injectors and arange that shuts all down but the manuel does not specify this I would think it differs with pcm calibration.
I will give you some hot parameters and you can experiment with some resistance values unless you can find a pot. in the app resistance range. on the hot side 2.75U 194f 2.3U 203f 2.0U 212f 1.5U 230f 1.15U 248f .89U 266f .54U 300f .28U 350f By the way i am using U for ohms and f for degrees ferinheight. Hope this is what you are after let us know what hapens. by the way there are two wires at the sensor one is a 5 volt signal from the computer and the other is the return signal or voltage drop after the resistance drop. the resistance is measured between the two pins.

 

Thats perfect! We have concord task one and two... So we are 1/2 way to the objective.

So now it looks like I need to somehow generate or recreate approximatley .89 Ohms

I'm glad I asked because I was assuming it gathered it's info from the Temperature Gauges sending unit. I was preparing to put the multi-meter on it while it warmed up to try to find out what signal it might need. I was hoping for volts but they couldn't make it that easy for me. So now I'm off to learn how to create controled resistance. Thanks for the help, if you think of anything else at all then shoot it my way.

 

Radio Shack or other electronics outlet to get .89 k ohms close tollarence resistor or combination of resistance and probably a double pole double through switch and some wiring. When i posted above I failed to mention those resistance values were k ohms (thousand ohms) so you will need a resistor of about .89 kohms or 890 ohms.
sorry for the missing K I jotted down all the values from a graph and forgot to add the K

 

Phew....I was wondeing how in the world I could get down to .89U + maintain 5v. V=IR was not working to well. I was thinking ok get a parometer (SP?) and a 12v-5v power supply And maybe I can choke the ohms with out losing Volts or amps... But I was skeptical at best. Back to the drawing board... At this point I really dont care if it saves any gas or not. I just want to figure this thing out.

 

Are you guys talkin english or japtalian?? So, how bout them Cowboys?? p.s. good luck on project pss

 

COWBOYS! THATS IT! A beaver hair wraped with leather will creat the perfect kohms! Just kidding

I like that...


Don't feel bad I dont really know what I'm talking about either... I'm learning as I go. You would think I could find something less important and cheaper than my trucks PCM to teach myself this wouldn't yea. This is the first project I have ever decided to take on that I have ever had to do this. All of my other projects were as simple as looking at the products voltage requirements and finding or making the appropriate Voltage supply for it.

 

Well good luck with the project and I envy ya. Hell When it comes to electrical I'm lost....just changin a bulb is a biotch! If I tried what your doin I can see it now.......Jeff hits switch and..........................BOOM! Mushroom cloud visible for miles.

 

Thats al "HUNKYSHOTHAND"

 

PSS, are you awhere there may be a bit more to the function that just subbing a resistror?
I have been looking at the monitor circuit and seems there may be a prerequisite condition before it's operation, to be valid.

 

Yea that was brought to my attention as well. I am currently looking for a copy of the PCED. (What ever that is "I was told that it's suppose to have the full schematics though")
We (especially I) but we as in my engineer friend that is helping me map the circuit. Want to see the full schematics before I purchase the bread board to ensure I get one with suffecient space for multiple circuits that it looks like we may end up having to mimic.

My brain hurts!!!

 

My info seems to suggest that the regular coolant temperature sensor has to be in the hot to overheat range with the lamp on before the CHT will be invoked.
I would think this is a normal 'stacking' operational process.
Chrysler is doing this now on some of their engines as well as some other cars.
These cars are a lot lighter than our trucks and can more eaisly miss the power from such an operation.
I think the Chrysler even automaticly does this in a cruise mode then come out full engne power for acceleration.
I would think Ford is looking at all these operational features.
There may just be a diesel in the F150 soon because this is the direction things are going due to gas costs vs fuel economy. How nice that will be for trailering with the lighter truck! Times' come!

 

The original idea was to trick the temperature gauge in to thinking it was over heated. Atleast it was untill this other came to my attention. The only real problem I have with that is IF something does go wrong. I might not know it for a few minutes because the CEL is already on telling me it's getting warm. I dont use the factory Temp gauge anyway so for it to say that it's getting hot is not a problem.

I came very close to buying a diesel when I bought this one. But I just dont want to mess with worrying about my fuel gelling or keeping it plugged in during the winter nor the extra initial cost.

 

All I can say is good luck on this one. I only have one real question. What about the cylinder compression? Isn't that really going to hurt the engine performance beyond the point of helping anything? If you knock out 4 cylinders thats 4 dead cylinders with full compression that you are carrying. Not to mention if the PCM isn't in the loop to kill the spark as well will that not cause damage??? I think that if there was a compression release mechanism this would be an awsome idea! If I am not mistaken i think the chryslers with this feature have a compression release but I am not sure. I really am interested to see what you come up with on this. Please keep us posted. It would be cool if you can make it work.

 

edited due to my mis interpretation.

Thanks I may need all the luck that I can get. LOL
I am going to try to install it this weekend. I have decided to get a used PCM from the salvage yard and install it as well during the trial and error phase. Hopefully more trial than error but just incase.

I hadn't thought of that... It defiantley won't be Maximum effiency because of the dead cylinders having compression. Hmm Hopefully there would be some gain. 30 mpg might be a stretch with that in consideration but low to mid 20's might not be.

Hopefully Ford will follow Chrylser and offer this soon. BUT I hope they add an over ride funtion so you can disable "Economy Mode" when pulling or hauling something. Can you imagine the verstility of a V-8 hybrid with this added too?