Same here - 14 guage speaker wire works fine and since it is a pair of wires bonded together it is easy to run back into the cab from under the hood.

 

I have a 94 F250 4x4, 7.3 turbo, auto, 178K, 3.55 RA, dual tank, regular cab, running 265/70/16 and getting 18 mpg. I have not had the time to do the balance test. I have hooked up the VM inside the cab and have just these readings for you: 3 mV at start-up with the advance and drops to 2 mV when the idle drops from 800 to 600 rpm. I will post more this evening. There was also the spike up to 6 mV when shut off engine.

 

I drove to the interstate at 3 mV the entire way at 40 mph 1400 rpm. On the interstate from 40-65 mph the readings rose to 5 mV until maintaining constant speed then it dropped to 3 mV. Each time I increased speed the reading rose to 5 mV and no matter the speed once it was reached the reading dropped to 3 mV. The exception was when I held it WOT the readings rose to 7 mV. It was more interesting when I had to let off the throttle and coast the readings dropped to 1 mV and even 0 mV. Is this correct or do I have something connected wrong?

 

I am questioning why some of us are getting readings in the 7.5 to 20.0 range while driving, while others are in the 0 to 5 or 6 range. I am taking my readings with a fairly decient Snap on digital meter, with the scale set to the 200mv DC scale. For interest sake, I flipped over to the 200mv AC scale, and was reading .2 .3, and up to .4 on that scale. Any ideas why we should not all be somewhat closer in our basic reading procedure??

 

7.3 force.......your readings are following the pattern of change with your driving as they should...........

they will spike up when your turn the switch off..........(no longer getting the cooling effect of the intake air flow as well as the the conversion of heat into power and excess heat going out the exhaust)

seeing a increase in readings as you accelerated is normal (the IP over fuels so rpms can increase)

seeing them go very low is normal with deceleration (lack of fuel to make heat)

try a few experiments with your driving habits...........such as using the readings as a point of reference as to your cruising speed or acceleration...............increase/decrease your speed (just a few MPH) for the lowest reading...........

do the simple things first......check air pressure in the tires.......air filter........check the seal on the snorkel....fuel filter...........now this one involves a little more work.......on the rear tires......with both at the same air pressure/temperature.....jack the rear of the truck up off the ground and with a cloth measuring tape check the circumference ......(I do not care if they are the same brand and size marked on the tires)..............make notes on what changes you make and how they effect the cruising readings.............(my) objective for (you) to achieve is .5 mv range difference between idle readings and cruising readings with a hopeful 10% increase in fuel mileage...........................

Kevin, with the information that a lot of the forum members has provided as well as my own readings on my 7.3 that are still in the 7's to 14-15's (even after new injectors installed), I now am fairly sure I have more than one problem with the IP..........I already know that the the IP is not advancing the timing as it should of which would effect upper rpm readings, But I can not get the idle readings down at any timing setting...................I have a rebuilt IP here that if I can find the time to install and test, then maybe I can find the reason for the high readings.....................??????

So far, with the information from my own readings and from other readings posted,,,,,,,,,the software is still predicting a optimum reading window from 1.06 mv to 2.65 mv's.....................please consider that mathematically, I can not get the number itself any closer because the the three old formula's that I use are one for F, one for C and one for K................I can plug in the exact same information and each scale will provide a different glow plug reading.................What I can be exact on is, we want the lowest possible range of reading from idle to cruising speed...............so, at this time, with the information we have at hand:

Glow plug reading target:

2.65 mv or lower at cruising RPM with a .5 mv range between high and low readings......................the range is More important than the number......................

Very Important Note: I need to see just as many high reading as low readings posted in order to develop a logical order of what changes to make to have the best results.......Not just throw money at the problem................

crossbones

 

I have a 35 mile drive to and from work so I will get readings twice daily. Should I post daily, weekly or when I have changes? I have re-read these posts and think I may have a leaky injector or bad glow plug as first morning starts take two turns of the key for five to eight secs each to ignite. I will try to get the balance test done and change any bad plugs. I do not have time to rebuild injectors or even pop test them just yet. Thank you for all your help. I have noticed if I stay at or below 70 mph I can maintain 3 mV until there is any incline or decline of the road. Also over 70 mph the readings sit at 4 mV.

 

7.3 force........just report different readings with any changes of the above that you see.............on your next report, also add the engine rpm at the speed that you are taking the readings..............also, I need to know the Ford recommended idle rpm for the automatics.................with and without the fast idle...........and any changes that have been done to the truck that is not factory..................are you using any fuel additives........
crossbones

 

Ford recommended idle RPMs for the c6 automatic are 750 with idle advance on, 625 with it off IIRC. That is pretty much exactly what mine are too.

I never mentioned that I'm using PowerService DieselKleen additive in my truck - didn't know that would be important. I mix it at 1 ounce per 3 gallons of fuel (1:384) which is just slightly higher than the low end of their recommendation to raise cetane 3 points (96oz:300gal or 1:400)

 

CB2, My truck is stock, it has brand new tires on it, I have not used any additives in it and I will get the circumference measurement of the tires on Friday. The RPM's I noticed were 35 mph at 1400 rmp, 70 mph at 1900 rpm. I am working on the recommended idle speed.

 

if a dso was hooked up to the g-p's (individually) could any of the info be usefull to determine proper/complete cumbustion and help with timing/fuel issues? (uhh.. am i thinking aloud again?)

 

I strongly believe you will see different "sets" of readings pending on the manufacture of the glow plugs. Company "A" may use a slightlydifferent material in the tip, while company "B" may use a larger diameter tip that's also longer resulting in higher readings for Co. "B".

Clear as mud?

The main objective as said before, is to lower the numbers with changes to increase effeciency.

 

Here is something I noticed and just wanted to check if it is normal or me. In the morning cooler temperature my mV readings are 2-3 until my RPM reach 2000-2100 then the reading are 4. In the afternoon hotter temps the readings are 3-4 until 2000-2100 RPM then they are 4-5. In the evening warm temps the readings 2 at idle 600 rpm, 3 until 1500 rpm, 3-4 til 2000-2100 rpm and 4 after that. It has been this way for te past two days with the unseasonably cool mornings here.

 

Mine has done about the same thing on a couple of cool mornings. I think the lower morning readings are due to the fact that the cooler air rushing in is cooling the GPs off more - which gives a lower reading.

At least that makes sense to me.

 

Cool morning air versus hot afternoon is just like comparing an intercooled engine to a non intercooled engine.

Cooler air into the intake means cooler EGT temps.
Cooler temps means lower readings from the glow plugs as well as what you see on the pyrometer for temps.

 

Hello......there are a few more things to consider when ambient temperature changes a lot during the day.........we must look at the "broad stoke categorization" of the "net effect" of things....first is when the lower readings were observed, was the CSD on of which advanced the timing some as well the fast idle increased the RPM's of which then could have set up the situation of where the RPMs and the timing were more closely matched .............intake air temperature changes has the "net effect" of a timing change...........as on a cool morning(without CSD on), as the heat increases in the cylinder it takes less "real time" for the fuel to be heated to auto ignition temperature.........so.........."heat" is a Big net effect when it comes to auto ignition timing.........

so, with the situation as described where the readings were lower with the cooler conditions, my recommendations would be:

see if the CSD is on, if so, then after the engine is hot would be to connect a jumper wire to the CSD and check the readings again.......if the reading go down, it hinting to a need to advance the timing some.........if they go up, it hinting to a need to retard the timing some.........................

please keep in mind the "net effect of things" before just changing the IP timing when up have readings down in the 2 to 3"s..................take 10 minutes to stand and "think and visualize in your mind" all of the net effects of heat on your truck....................water temperature, air temperature, fuel temperature................from my original post I stated we would be using the "most powerful computer/dyno in the world"...................

crossbones