I don't know anything about electrical theory. That said, if you look at the readings I collected, you will see that they were very telling. I am guessing that the use of a common ground for one lead of the volt meter and low voltage for the test, isolates the current enough to get a reading. If your theory were correct, I should see the same readings for all terminals. That was not the case. All I can say is try it yourself. My ground was attached an unused bolt holeon the manifold.

 

Crossbones,
Another factor on efficiency of these diesels with precombustion chambers is the size of them. Did the Ford diesels come with different precombustion chambers? I'm familiar with GM 6.2/6.5 diesels and the earlier non heavy duty 6.2's had smaller combustion chambers and would get better gas mileage but had less power than the later versions with larger precombusion chambers. I own the first year 1982 6.2 diesel suburban and I routinely see upper 20's on the freeway. Perhaps I should super tune this engine and maybe I'll break 30 mpg. Thanks for the very interesting and informative posts.

 

Hey crossbones2. Care to comment on this? I thought you wanted individual readings with the GP harness disconnected. I don't know how he is getting different readings on each wire of the cat 5 cable if the GP harness is still attached to the GP relay and he has re-attached the GP wire to each GP after attaching the cat 5 wire. I suppose the length of each wire of the GP harness would give him a different reading by way of resistance of the wire. Not to question his readings, but I don't think he is getting a TRUE reading from EACH GP.

 

I think the confusion is "I left the connector on the other end" does not necessarily mean he re-connected the glow plugs. Sounds like he just left the RJ45 connector on the end of the cable inside the cab for easier connection to a "test block".

 

Tom D and other members, first let me say that I am not a electronics "person".... I can not explain pasotx's findings and can only state my experience. What I have found was when the glow plugs were attached to each other by the wiring harness that I got a reading from the highest reading glow plug in the attached circuit. I would think that a Zener Diode would have to be on each glow plug between the harness and the glow plug and then the readings taken at the glow plug for this to work. (I can be totally wrong).

Individual glow plug reading would be a major plus in getting each cylinder balanced with on the road test.

Now, in all honesty I very quickly learned that the typical "test for a good or bad glow plugs" using a test light or ohm meter on a cold glow plug did not give me the best cold starts or uniform glow plug readings. I am going to describe one way that I did a "balanced glow plug test" This is not to say that you have to do it this way, but to explain what I was looking for and how I used the information in steps.With the engine hot, I would disconnect the glow plug relay(safety) and then take the individual readings writing them down, establish the median reading of all the glow plugs. I then would take one of the median reading glow plugs and then swap it into the highest reading cylinder or the lowest reading cylinder and see if it was a "bad glow plug" or if it was a problem with the cylinder.....if it was the glow plug, then I replaced it, if it was the cylinder then I would investigate the cylinder in question. I continued this process until I had all glow plugs reading within about .5 to 1 MV of the median number.

As my learning curve improved, I found out that usually I would save my self a lot of time and work in the long run when "tuning a different truck with the same engine" that if the the individual readings were not close to the median readings of the previous truck I would change my "steps"......If I could not get all of the glow plugs to read at the median number with changing a couple of glow plugs, I would then do the following steps:

you write down everything for each cylinder

Hot engine compression test.........compare readings to each other and factory speck...

super clean the injectors and set the pop off (get all injectors as close to each other as possible and they Do Not Bleed Off below the speck PSI) write down each pop off speck and mark each injector....

then do another individual glow plug test and this time it should be easy to get a "balanced set of glow plugs"

**Once you have a "balanced set of glow plugs", then you can just hook up to the glow plug system at a single place and get your readings.**

Depending on the "results that you wish to achieve", you can adjust the amount of work and time (steps) to your needs.....

I know this sounds like a lot of work, but just keep this in mind, I bought a 1989 roll back from a original owner that stated he never got over 10 MPG from day one............I am in the high 13's and low 14's now, and the truck is a long way from being "tuned" and I have more power than I need. (just wish I had the time to get it "right")

Ed Hall, yes, the early 1980's engines were more closely designed for "effecient fuel mileage", then as years past the word "effecient" was transposed to mean "effecient usage of the fuel to produce more power at the expense of fuel mileage"............todays passenger vehicle engines produce from 50 to 60% or more power than is needed for typical highway use.....in the early 1980's and before there were several engines (both diesel and gasoline) that got fuel mileage in the very high 40's and low 50's.........there is Only One reason for the typical passenger vehicle Not Getting Much Better Fuel Mileage Today Than in the 1980's.....

"the flow of money from weak hands into stronger hands"

crossbones

 

[QUOTE=crossbones2]Tom D and other members, first let me say that I am not a electronics "person".... I can not explain pasotx's findings and can only state my experience. What I have found was when the glow plugs were attached to each other by the wiring harness that I got a reading from the highest reading glow plug in the attached circuit. I would think that a Zener Diode would have to be on each glow plug between the harness and the glow plug and then the readings taken at the glow plug for this to work. (I can be totally wrong).

Crossbones2 that would probably work. I think the easiest way to get individual GP readings is to disconnect the individual wires from each GP and hook up the cat 5 cable. Be sure to disconnect the GP relay while the wires are disconnected. Now some will say "how can I get the truck to start without the GP's connected?" Start the engine initially with the GP's, warm it up, shut it off,disconnect the GP wires and relay, hook up cat 5 cable. I know, what a pain in the butt. If you want an accurate reading of what is going on in EACH individual cylinder, the effort is worth it. CB2 hit it right on the head.
Incidently...GREAT THREAD. MUCH CAN BE LEARNED HERE.

 

I like the idea of using diodes on the glow plugs in order to get on the road indvidual readings. In order to do this you would need to know the current draw and peak inverse voltage that the diodes would be exposed to.
I therefore tried to find the current draw of the motorcraft/beru ZD-9 glow plugs used in my 1990 F250 7.3L and I can't find that info any where. We know the peak inverse voltage would only be in the milivolts so that is not the problem. Does anyone know what the current draw of a glow plug is?
Jim

 

tradergem...I am going to make some guesses based on my experience and some tid bits of information I have pick up about the glow plugs in a 6.9-7.3 engines. I believe the glow plugs are 9 volt rated????..........typically a individual glow plug's instantaneously current draw is about 50 -55 amps on a 6 volt rated glow plug.........now there is a very rapid decline in amperage draw as the plug heats up and voltage will rise accordingly.......I would guess at about 35-40 amps instantaneous current draw per on these glow plugs.....

I hope that helps some,
crossbones

 

Super Tuning an engine, nice thread I myself always wondered how sum can get great mpg and others terrible. My very first diesel which was purchased over 10 years ago was an 83 F250 sc xlt 6.9 rotomaster turbo 4 speed 4.10 gears. I purchased this from John Healey of Tasca Ford Fame. John was the wrench behind Tasca's drag cars of the 60's and 70's,He was one of the first to get Fords sohc 427 cammer running really good. It was the engine with two cams one on each head with a timing chane around 6 feet long. After Tasca got out of racing John opened up his own shop in RI. It was the early 70's. I can recall in the mid 70's when the fuel crunch hit us he was super tuning the big Lincolns Fords and Mercs with the big 460's. He would have Crane Cams grind special cams and set special distributor timing crurves on one of those osciliscopes. People would drop off a 7-9 mpg gas guzzlers and a few days later drive away with a car that would get 12-14 mpg. In the 80's John built many record setting race engines and built a record setting Competition Eliminator T-bird for a guy in Florida. He would maintain the racecar here in RI and tow it to the races with the 83 diesel towing a 37' tri axel race trailer. They raced Division 2 which was the SE so a trip to the track was leave RI and race in Carolina ,Georgia and Florida. I later found out this truck made 5 trips to the coast. That would be the west coast. When I bought the truck the odometer had been around a few times. I ran the truck for a couple of years and the crankcase would fill with diesel fuel and it was parked. I later bumped into John at the races and told him I still had the truck. He said that was a great truck and got 17mpg towing the 37' race trailer. I never got a chance to tow heavy with the truck and cannot confirm this. So how did this 6.9 diesel get 17 mpg towing at least 10,000 lbs with no overdrive. Did John due some supertuning on the diesel. Did he figure a way to make that diesel a fuel miser or was it a fluke

 

Well, I'll bet he might have done what I am about to do.

Advance the pump timing and simply install smaller/less HP injectors like the ones I pulled out of a 1992 "E" series Diesel van.

They were pulled by mistake but now that I had time to think about it, with the hope of them working better than the ones I have now.

I'm told there can be up to a 40 hp varience in the power levels between the smallest and largest injectors for the 7.3.

Perhaps there might be a mileage advantage as well.

 

If you go ahead with this, please let us know what happens. I am pondering injector options too...

 

Yeah, I wanted to get and run a tank of B100 in it before I did the swap as it should make less of a nasty mess than DinoDiesel when it leaks all over the place, and the speedway by my work said they had Biodiesel-----HA, it was only B11.
11% should not be called Biodiesel, I think 51% or better should have the right to use the name

And of the only other 2 places I could find, 1 is only 9 to 5 and I rarely am around those hours, (they do not list if it's B100 or less) and the other is a SAPP BROTHERS truck stop (and they only sell Soybean B100 there, no DinoDiesel) about 67 miless away out in the sticks off hwy 80!

But work has me driving out that way tomorrow and I'll see if they can sell it in 5 gallon buckets that I can drag back to my personal vehicle.

2 minutes later, YES, but I need to bring my own buckets as B100 is is biodegradable and non-toxic so no special "FUEL" containers.

 

Well I got the SOY based Biodiesel, and after running it until the engine started making that (you are out of fuel now stupid) noise, pulled over, added the 3 gallons of Biodiesel I had in 2 gas cans and went home to top it off and have been running it all day today and put on about 40 miles or so.

DAMN!!!

1: Both my daughter and I swear it runs quieter!

2: The nasty raw fuel smell is gone!

3: The smoke on cold start-up is less than half of what it was on DinoDiesel!

4: The idle smooths out faster right after cold startup!

5: The slight smoke on warm startup is gone!

6: And it feels like its running stronger, but all this might be from the BioDiesel cleaning things out (as all the Biodiesel Info online said it would) rather than the fuel itself, but the info sheet they gave me when I got it also said to expect more power with the Biodiesel!

7: All this and it's the right kind of fuel ecologically speaking?

I am 100% sold on biodiesel!

 

maybe your fuel is better than the stuff they sell at texaco here, but the crap i run has made my truck run like crap after running it the first time i changed the fuel filter and went back to ulsd. i got some bio from a friend and it was ok for alittle bit then it started missing again. alot when cold. you can hold the throttle at 2k and it will by itself go to about redline. im not sure if its just getting starved for fuel for a second then gets fuel or if it did something to my injection pump or injectors or what the deal is. there is alot of light blue smoke as well which i know could be signs of bad valve guides and seals which is a comon with these trucks with 200k like mine. I swear though last time it did this i changed the fuel filter and ran regular diesel and it ran great again. plus i get ulsd cheaper than buying bio unless i was to make it myself.

believe me im not in it for the environmental concerns because man made global warming is a lie and bio diesel acually there was a artcle put out saying bio acually produced more nitrous oxide emissions than petro diesel. other than that if i could get a decent batch id consider running it for being more lubricative than ulsd

 

Archangel,

Have you done your injector swap yet? I am curious as to your results, since I have 2 conflicting theories in my head and am wondering which one is right regarding injectors and efficiencies. Here are my two thoughts:

1. Like Archangel's thinking, smaller injectors will flow less fuel and lead to economy improvements because there will be less waste at hard throttle application.

2. Higher flowrate injectors can result in higher efficiency because a certain amount of fuel is required to maintain engine RPM at any point, but the bigger injectors will deliver the same amount of fuel over a shorter period of time (duration). The amount of fuel delivered per combustion cycle should be the same, but the pulse will be faster. This would allow the timing to be retarded slightly, resulting in less backwards pushing on the piston, meaning higher efficiency.

Now, discuss which theory is more right so we can all learn something.

-Arthur