Get a beer (6 pack) this is gona be a long one...

I’ve been trying to put together some information on IP timing using the luminosity probe and this is what I have come up with.

I couldn’t wait any longer it was nice today, van is to tall to get in the garage – 40F and only light rain so I decided to check the IP timing on the van 1993 7.3 NA IDI. I used the Snap-On MT408 with the luminosity probe. This type of probe allows you to use either the number 1 or the number 4 cylinder, where as if you use the pulse you need to use the number 4 injector on the E-series van, and the number 1 injector on the F series. The van had been getting 17.8 mpg country driving and 16+ country / highway mix. Exhaust smoke – was light and blue in color at idle even after running around and engine at running temperature. Over all, other than the smoke at idle, the truck was running pretty nice. I’m looking to improve mileage, power and get rid of the smoking as much a possible through injector pump timing – keep in mind that my van has 155,000 mile on the motor and the IP, injectors, and GP as far as I know are all original, yes replacing these would probably help mileage, power and smoke reduction, but have also noticed that there are a lot of questions being asked (on all boards) regarding power and some even after new IP, injectors, and GP’s have been installed.

Diesel fuel: Citgo gold

Additives: Power service additive 1/2 quart per 30gallons, Marvel Mystery oil 1/2 quart per 30gallons on occasion.

Oil: Shell Rottela T synthetic 5w-40<O</O

Word on Cetane: I always use a good quality fuel and fuel additive, I believe the cetane value of the fuel I use with the additives to be in the 45 range although I did not use this as a basis for any timing position consideration. I also do not think this has any more effect on the timing using the luminosity style probe than the pulse style probe – if you get bad fuel it will change the way your truck runs…
<O</O
Before getting started with the timing procedure make sure the probes you are going to use go in easily once the engine is at running temperature and read the instruction guide for the MT480. The hardest part was cleaning out the hole (top one on Fords) that the magnetic probe goes into down by the harmonic balancer. Took an hour with a piece of rolled up sand paper to get the rust out. I used the number one cylinder glow plug for the luminosity probe because it’s the easiest to get at on the E-series van. I cleaned out around the glow plug area and then pulled the glow plug. I modified a deep-well 1/4” drive 3/8” socket so it just covers the nut portion of the glow plug. Using this socket, a six inch extension and a universal joint you can pull any glow plug on a 7.3 NA IDI without removing the injector lines. I then cleaned the glow plug and put it back in. The next big hurdle is loosening the three 9/16 nuts on the injector pump. DO NOT LOOSEN THE NUTS AT THIS TIME ONLY MAKE SURE YOU CAN GET TO THE NUTS. I used three different wrenches to get the pump loose: 9/16” open end wrench for the top, a 9/16” box end wrench that was ground and bent allowing you to get on the nut down to the left of the IP, and one short 1/2” - 9/16” wrench ground to allow access to the lower right hand nut on the IP.
<O</O
Once you have your wrenches ready to go, and you know the magnetic probe will fit, and that the area around the glow plug is clean. Start the truck and drive around for 15 or 20 minutes to get the engine up to running temperature.

The MT480 instruction guide tells you to “make sure the magnetic probe is touching” the balancer. Through research I found that running the magnetic probe against the balancer will cause the probe to fail prematurely and it had been suggested to use a feeler gauge to ensure that the probe does not contact the balancer, the thickness of the feeler gauge was not mentioned so I used a thin piece of paper (about 0.003”). I put the paper between the balance and the magnetic probe bracket then pushed the probe all the way in. Once the magnetic probe bottomed out I removed the paper.
<O</O
Next - Read and follow the instruction guide for the MT480 for the proper setup of the timing meter – once all leads are in place tie strap all wires to ensure they will not be pulled into the fan belt or fan.
<O</O
There seems to be a deference in “degrees offset” between the pulse and the luminosity type probes and that is one of the reasons I wanted to do this post - to find out if this is true. It seems that 8.5* BTDC @ 2000 rpm is the spec setting in the Ford manual (1993 7.3 IDI) that I have and it’s for the Pulse type adapter only, and it seems to works very well at that setting when the pulse adapter is used. There are no other reference to any other adapter types in the 1993 manual - this is another reason I wanted to do this post – to get some working numbers for the luminosity type probes. For the most part I don’t believe that one type of probe is better than the other, they are just different. From all the hunting around I have done it sounds like 0.5* to 1.0* ATDC @ 2000 rpm is good power and economy setting for the 7.3 IDI engines using the luminosity type probes.
<O</O
Ok to the meat and potatoes: I got the meter and probes connected as per the MT480 instruction guide, and disconnected the electronic cold advance. Started up and let it settle for a while at idle, the readings were as follows – RPM 650, timing offset 10* ATDC. At this point I ran a jumper wire from the “+” lead on the battery to the spade plug for the electronic advance on the IP. The advance moved the timing about 1.5* towards “0”, removed jumper wire from cold advance (left cold advance wire off). Next I increased the RPM to 2000, timing offset was at 18* ATDC. Before moving the IP I checked the scribe marks, they were lined up. It took a while but after shutting down the engine and moving the injector pump three times (wound up 3/16” off of original marks on IP housing) I got the setting I wanted 0.5* / 1.0* ATDC @ 2000 RPM. Using a 5/8” open end wrench I loosened the top four injector lines at the injector pump and all lines at the injectors each time I moved the injector pump, this made movement of the injector pump easier –remember to retighten lines before running engine. I believe my IP advance is working because the luminosity probe picked up the combustion (after allowing a little time to settle at a steady rpm) at the same degree offset - held at 0.5* / 1.0* ATDC from 650 rpm to 2000 rpm. I found it curious that the timing offset was off 8* between 650 rpm and 2000 rpm when I started but as I moved the IP timing the offsets moved closer together and wound up being the same in the end… Remove all test equipment, tools, double check nuts, bolts, and injector lines to make sure they are tight.

Time to go for a drive… All I can say is I LIKE IT, WOW and THE SMOKE AT IDLE IS GONE BABBY – it was dark so I used a flashlight and I don’t see any smoke at idle! She’s got a little rattle to it when you step on it, it’s dark out so I can’t see any black power smoke but I don’t think I went that far anyway. I’ll keep and eye on the mileage and let you know what I find out…

I LIKE IT - 93

 

thanks for sharing that info. I am going to file it away for futurn reference. So just to be clear, your timing was off by 8* ?

How much does the snap on timing tool cost if you don't mind saying so..
and where can you get such an item

Rick M

 

FMohlmann,

The timing was at 18* ATDC @ 2000 rpm before I made any adjustments. The difference between idle (10* ATDC @ 650 rpm) and 2000 rpm was 8* when first checked. When I finished both 650 rpm and 2000 rpm read about the same 0.5* to 1.0*. Like I said in my first posting I found it curious that offsets wound up to be almost the same at the end – I’d like to know why?

As far as the smoke goes it did not start dissipating until I got around 3* ATDC…

A little more information on my van: The fuel Tank, The fuel pick up in the tank, the fuel line to, and the return line from the engine are relatively new. The fuel filter, lines to IP, lines to the injectors, and injector O-rings have all been changed with in the last 2 months. My O-rings and small line between the injectors were leaking and this too would contribute to smoking, power loss and poor fuel mileage. What I’m getting at is the timing alone might not have fixed these items so beware…

Snap-On MT480 - These style meters are no longer produced – probably because the pulse adapter styles are a little easier to install, the only draw back is having to hold a timing light. Used lumy/mag (uses a luminosity rather than a pulse adapter) style timing meters (Snap-On, Kent More, and Ford Rotunda) can be found on the internet – EBay and sites like that for anywhere between $100 and $300 depending on style and condition. You can take your truck to a diesel shop and have this done but most of the feed back from people doing this has been negative. So spend some money and learn about your engine and fine-tune it to fit your needs… The pulse adapter styles seem to work well also so don’t forget about these. Again the only thing with those is you might need a tach if you don’t have one in the dash (I don’t have one in the dash) and you’ll also need a timing light – search the this site and internet for more info on those.

As far as filing this away wait until some other replies come in. I’m only doing this to generate information (mostly for myself - LOL) on using the luminosity style meters – I could not find any single source that really tells you how to use them.

93

 

Also missing from my original post was "check the service manual for your engine regarding IP timing". Find out what sensors need to be disconnected - cold idle, stuff like that...

93

 

So you moved the pump 3/16" was that towards the passenger side?

 

Tuke,

Yes I moved it about 3/16 to the passenger side when leaning over the radiator. I did not have a set number in mind when I moved it; it’s just where it ended up using the MT480. Keep in mind that my injectors and pump have there best years behind them – lol. Personally I would not move anything unless I had some way to get actual readings that way you can always go back.

<O
When I started the truck this morning (only dropped to about 35F overnight not plugged in) there was a tint of light blue smoke (about a quarter of what it used to be) until it got up to running temperature (drove around for a while) then no smoke at idle. Also my electronic cold idle advance hasn’t work sense I got the truck about 18 months ago – looking into get a new solenoid some day…

<O
I just came back from an 80-mile ride over country roads. This is what I found: When I tromp on it I get black smoke, not heavy but you can see it coming out of the exhaust in the side mirror through 1st, 2<SUP>nd</SUP>, and 3<SUP>rd</SUP>, and overdrive – good power through all. I would say that it’s probably about right. Accelerating slowly I’ve got real good power in 1<SUP>st</SUP>, 2<SUP>nd</SUP> and 3<SUP>rd</SUP>, overdrive is a dog between 45 and 60 mph (E40D), if I’m going 45 to 55 and push the throttle down with any force I get heavy black smoke. I am thinking about backing off on the fuel screw about ½ a flat to see if I can get the heavy black smoke to thin out a little in the 45 to 60 mph range.

<O
93

 

So would you highly recommend making these timing adjustments? I am a little fraid of blowing up my truck knowing my luck lately...Did you notice alot more power after the timing adjustment?

 

Because I do not have a turbo I don’t think I’ll ever notice a lot more power. And I would not make any moves to the timing with out some type of timing meter (my hearing isn’t that good anymore) be it the pulse or the luminosity style. I’m trying to find a point where I can go up modest hills hauling 3000 to 4000 pounds and keep up with traffic, and still get reasonable mileage. I have a meter that uses the luminosity style probe and there is not a lot of info out there using this probe on the 7.3 so I’m working my way into it. Right now I’m wondering if I should cut back on the fuel or advance the timing more? I’m starting to lean towards move the IP advanced a little more…

If Spectramc checks in I’d like to know if he’s been through this “area of timing” where you seem to get power / black smoke and then went further and the power increased on the low rpm end?

93

 

I found this on another website today...

On the 7.3IDI, there was only one recommended timing procedure and one recommended spec. The timing method is called "line pressure" timing and uses a pick up that senses the fuel pressure pulse going to the injectors. One the "F" Series, there is a special adaptor on injector #1 (#4 for "E" Series) and the pick up clamps on this adaptor. The meter compares the fuel impulse to a crank damper pick up and determines the timing. The Ford recommended spec is 8 - 9 degrees BTDC. Anything more than this and the combustion noise gets pretty loud. Timing less than this can cause long crank/hard starting/poor performance/white smoke/lower fuel economy.

The Ford 6.9 used "luminosity" timing. The timing pick up was an adaptor that allowed a light-sensing pick up (placed in GP hole) to actually see the combustion occurrence and use this to compare to the crank position pick up. In this case, since combustion had already occurred, the spec was ATDC (.5 to 1.5 degrees).

This evening I moved the timing so it was a degree or so BTDC @ 2000 rpm to see what would happen. The engine seemed to have a lot of backpressure (pre-detonation?) when starting, lost power (wouldn’t accelerate once it hit overdrive), and it was pretty noisy. I changed the timing to 2* ATDC @ 2000 rpm still no smoke at idle, and the power seemed better than it was at 0.5* to 1* ATDC @ 2000 rpm. I’m going to leave it here for a few weeks and see what the mileage looks like. I will say this if your going to use a luminosity probe .5* to 1.5* ATDC @ 2000 rpm seems comparable to the pulse at 8.5* to 9*. I believe that my current setting of 2* ATDC @ 2000 rpm using the luminosity probe is about 8* BTDC if using the pulse type probe.

93

 

Here is something to consider- from my Haynes diesel teck book page 3-31

You must consider fuel cetane value for timing the IP.
4-68J ROO 4-68X
cetane value 38-42 3.5 deg ATDC 4.5 deg ATDC
43-46 cetane 2.5 deg ATDC 3.5 deg ATDC
47+ cetane 1.5 deg ATDC 2.5 deg ATDC

This applies to the 6.9 engines only

I put these in columns but doesn't want to stay when sent.

 

Thanks for the reply bigredtruckmi,

The cetane value was another issue I encountered while trying to find info on the use of the luminosity style probes. Number one I have not been able to find a cetane meter. The next issue is the suggested cetane / timing value. I don’t have a lot on this but there are varying opinions, depending on the manuals, on that too.

Here’s one from autozone -

https://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/0a/34/ba/0900823d800a34ba.jsp

They’ve got the cetane / timing value’s like this:

(I think 4-68J ROO 4-685 is in reference to the altitude?) If you have info on that I’d like that too.

<TABLE style="BORDER-RIGHT: medium none; BORDER-TOP: medium none; BORDER-LEFT: medium none; BORDER-BOTTOM: medium none; BORDER-COLLAPSE: collapse; mso-border-alt: solid windowtext .5pt; mso-padding-alt: 0in 5.4pt 0in 5.4pt" cellSpacing=0 cellPadding=0 border=1><TBODY><TR><TD style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: windowtext 0.5pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0in; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 110.7pt; PADDING-TOP: 0in; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent" vAlign=top width=148>Cetane <O</O





</TD><TD style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: windowtext 0.5pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0in; BORDER-LEFT: #ece9d8; WIDTH: 110.7pt; PADDING-TOP: 0in; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; mso-border-left-alt: solid windowtext .5pt" vAlign=top width=148>Altitude 0 - 3000ft<O</O





</TD><TD style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: windowtext 0.5pt solid; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0in; BORDER-LEFT: #ece9d8; WIDTH: 110.7pt; PADDING-TOP: 0in; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; mso-border-left-alt: solid windowtext .5pt" vAlign=top width=148>Altitude above 3000ft





</TD></TR><TR><TD style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0in; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 110.7pt; PADDING-TOP: 0in; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=148>38-42





</TD><TD style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0in; BORDER-LEFT: #ece9d8; WIDTH: 110.7pt; PADDING-TOP: 0in; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=148>6* ATDC





</TD><TD style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0in; BORDER-LEFT: #ece9d8; WIDTH: 110.7pt; PADDING-TOP: 0in; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=148>7* ATDC





</TD></TR><TR><TD style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0in; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 110.7pt; PADDING-TOP: 0in; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=148>43-46





</TD><TD style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0in; BORDER-LEFT: #ece9d8; WIDTH: 110.7pt; PADDING-TOP: 0in; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=148>5* ATDC





</TD><TD style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0in; BORDER-LEFT: #ece9d8; WIDTH: 110.7pt; PADDING-TOP: 0in; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=148>6* ATDC





</TD></TR><TR><TD style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0in; BORDER-LEFT: windowtext 0.5pt solid; WIDTH: 110.7pt; PADDING-TOP: 0in; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=148>47-50





</TD><TD style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0in; BORDER-LEFT: #ece9d8; WIDTH: 110.7pt; PADDING-TOP: 0in; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=148>4* ATDC





</TD><TD style="BORDER-RIGHT: windowtext 0.5pt solid; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0in; BORDER-LEFT: #ece9d8; WIDTH: 110.7pt; PADDING-TOP: 0in; BORDER-BOTTOM: windowtext 0.5pt solid; BACKGROUND-COLOR: transparent; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt" vAlign=top width=148>5* ATDC





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I guess what I was trying to say is that there could be a window – say 1.5* to 4.5* ATDC @ 2000 rpm for the 6.9 / 7.3 Ford style engines, 3* covers all cetane ranges regardless of altitude or cetane value. (I used the numbers you gave me because they seem to be close to what I’m seeing on my engine). Also my engine did not stop smoking at idle (650 rpm) until I got under 5* ATDC @ 2000 rpm, I can’t say at exactly what timing degree it was at when the smoke stopped but it was smoking when I checked it at 5* ATDC. Then when I checked it again after moving the timing, I was at about 1*, and it no longer smoked at idle. Why wouldn’t cetane have an impact on the pulse type adapter? Is every one setting the timing at 8.5* BTDC @ 2000 rpm when they use the pulse method or is there a window? If the cetane value affects the burning rate of the fuel (and we know it does) then it would be of benefit to both types of timing to know this value. From what I’ve found timing the engine using the pulse method has a 2* +/- window for checking and a 1* +/- window for setting, is this due to the cetane value? I think this is why the very experienced diesel mechanics (sounds better than the old-timers – LOL) would do the dynamic timing by ear even if they got it close using “a” timing meter.

Also worth noting -

<O</O
While trying to find information on how to use a meter with the luminosity style probe I ran across this on another site (sorry it was a GM site, I washed my eyes out with soap when I was done reading – LOL):

• GM spec calls out TDC @ 1400 RPM, and Ford's NA specs vary depending on the elevation and your fuel cetane rating. Figures range from 4° to 7° ATDC @ 1400 RPM. There are many members on The Diesel Stop Forums, have found that advancing as far as 8.5° BTDC @ 2000 RPM provides a great deal more power with the tradeoff being some increased smoke and a little more diesel rattle. It may not be the ticket for everybody, but it's worth a try if you have the time.

Again the above reference was made in an article describing the use of the luminosity style probes, I believe they got mixed up and referenced a forum discussing timing using the pulse style adapter?

93

 

Again from the book. Use a Ford Rotundra tool # 078-00121

Cetane value is determined by measuring the specific gravity (density) of the fuel with the fuel temp between 75-95 deg F. Poor quality fuel can affect diesel engine performance.

Check cetane value as follows:
A. fill the hydrometer container with fuel until hydrometer floats.
B. Gently spin until unit breaks surface tension. Read the number at the lowest point of the fuel level on hydrometer. Record that number. refer to chart.

hyro reading - cetane value
.837 - - - - - - - - -50 cetane
.846 - - - - - - - - 47 cetane
.849 - - - - - - - - 46 cetane
.858 - - - - - - - - -43 cetane
.862 --------- - - - -42 cetane
.876 - - - - - - - - - 38 cetane


Hope this helps..

I run 51 cetane fuel with B20 soydiesel in all my vehicles on the farm. Runs great and our local school moved to the same fuel and it has solved a LOT of problems they was having with smoke (both blue and black)and running problems solved. We had some older (1992) buses which wouldn't hardly run while cold but now run like new . Go figure.

 

I didn't find anything aboout high alt. operation in the timing of the IP but someone else who lives in these areas could help with this. And I am wondering the 4-68J ROO and 4-68X ROO might be different IP's. Anyone know for sure??

 

HUH??, it's no wonder I took mine into a shop to get done.

 

That is exactly what they did. The luminosity probe is seeing the fuel start to burn which would be bad before TDC was reached. The pulse method is sensing the fuel on the way to the injector which is way before it starts to burn.

I do not have my book here, but I seem to remember my 6.9 timing values range from 1.5 ATDC to 3.5 ATDC depending on fuel cetane value.

Somewhere I also have a cetane value to specific gravity value chart, so all you would need to do is use a hydrometer at a specific fuel temperature to check the cetane rating. I am not sure how accurate that would be with the modern low sulphur diesel though since the chart was from the days of high sulphur fuel with 5000 PPM.

I think the R and X pumps are the same pump, but the fueling curve is different. I also know they have different timing specs, the timing is more advanced on the X pump. The X pump also gives a higher HP than the J pump does.

This would lead me to believe the J pump is the high altitide pump, less fuel, less power and slower timing to reduce smoke under load at high alittude.