One new thing I forgot to say is with the NEW ULSD fuel which came out this summer. Use a fuel additive - to help with lube of the fuel injection pump. Whether it is one you mix with fuel or get a fuel such as biodiesel already premixed.

 

Bigrestruckmi and Dave S.,

I think your right about the 4-68J ROO and 4-68X ROO. I remember running across a reference to IP’s regarding low and high altitudes and the fuel curves for each.

Also Bigrestruckmi, what did you use to test the cetane of the fuel – brand and range if you have it? I think I may have found one on line, talk about a needle in a haystack, for $60.00. API gravity range between 29 and 51.

And finally do you check the timing on the diesels, if so what do you use the luminosity or pulse style?

Thanks, 93

 

I got the cetane level from my fuel supplier ( who had it on line ) crystal flash energy of michigan. I just checked and they changed the web site and the specs are not listed (bad url)

 

With the last timing adjustment I made using the MT480 luminosity style probe (now at 2* ATDC @ 2000 rpm) I can tell you this: I started it this morning, overnight low in the low 30's and not plugged in, and it smoked very little. The light blue smoke was not even a quarter of what it used to be at idle even when it was at full running temperature. It does rattle more than it did before when cold, once it comes off the cold advance then quiets down. Once the truck is up to running temp (I drove around for a while then parked it) it does not smoke at all anymore. The throttle response seems a lot better. When I gun it while parked I get a puff of black smoke, about a lungs worth - LOL. While driving with the seat-o-meter hooked up, there does seem to be more power and better acceleration now. Once in overdrive I slowed back to about 35 miles an hour, but still in OD, if I give it as much throttle as I can without kicking it down into passing gear the truck accelerates with a light amount of black smoke – I think that’s pretty good for OD. I’m going to leave the timing here and see what I get for mileage.

As far as recommending a setting I’ll say this: Either buy a meter (either the luminosity style or the pulse type) or find someone that has one. Then I would start out at either 2* ATDC @ 2000 rpm using the luminosity probe or 8* BTDC @ 2000 rpm using the pulse adapter. Take it for a test drive and then make adjustments as needed. Again my van is a 1993 with the 7.3 NA IDI.

<OCetane hydrometer: I’m going to get one. I’m going to take a sample out of my fuel tank for a sample that way I can measure the additive effects as well. It will probably be a few weeks before I do this but once I do I’ll give you an update.

<O93

 

Ok this is what I’ve got. I’ve just been doing the country errands; 3 days cold starts (not plugged in, overnight temps around 30F) warmed up until engine was at least in the low-normal range. Took the boat over to storage about 8 miles away, few trips to the auto store, fleet-farm, and wal-mark. All told a little over 155 miles, took 8.5 gallons of fuel = 18.235 mile per gallon.

I’m really happy with that especially with the short trips, the power seems better also. But I’ve done a little rechecking this evening trying to figure out the first set of timing numbers I got (18* ATDC @ 2000 rpm, and 10* ATDC @ 625 rpm) before I moved anything, and why when I got closer to TDC they seemed to catch each other? Well I checked the timing a few times and what I found was that the timing is moving around between about one degree at 2000 rpm (between 2* and 3* ATDC), and between 3* and 4* BTDC @ 650 rpm. As I increased the rpm from 625 to 2000 this is what I saw, pretty much as soon as I got above idle the needle came to or almost TDC. About 1200 it was a little over .5* ATDC, and by 1400 it was about 1* ATDC, 1800 was about 1.5* ATDC, and 2000 was about 2* ATDC. All of these numbers were plus or minus a percentage of a degree. I think the black smoke I was getting at low rpm’s before I bumped the timing from .5*/1* ATDC to 2*ATDC @ 2000 rpm (pumps now about 1/8” to the left of the original timing mark) was just the timing being below .5* ATDC or possibly BTDC during low rpm acceleration.

I have questions that I’d like to get some opinions on –

Question 1. I’m thinking the IP is just plain worn out. While moving the IP timing does seem to help, the engine really does feel like it has more power and I believe I’ll get at least a little better fuel mileage. I’m wondering what it would be like with a new IP and possibly injectors also?

Question 2. On an engine with a new IP and injectors does the timing follow from 650 to 2000 rpm? Or does it advance at a faster rate as the rpm’s increase. Certainly I would expect it to retard as it’s doing now? Is there some type of a curve?

Question 3. The cold advance seems to work, it advances about 1 or 2 degrees when hot-wired. Moving the mechanical advance lever while running at any rpm changed nothing. The lever / plunger seem to move ok but do nothing to change the timing offset. I’ve been using additives for about 14 months (got her in July 2005). Is there hope for freeing up mechanical advance or is it time to replace the injector pump?

93

 

if someone comes along sometime with experience,or has heard of a worn ip causing erratic timing id like to know as well.this will help me determine when the ip needs to be changed if this is the case i suppose?
answering these questions above will be appreciated.
93_E_350's Last Activity: 12-02-2006 ......bummer.id like to hear more long term test results.