Low power/MPG on 1990 166hp 7.3 IDI

[metermatch]

I have some questions about my 166hp 7.3 IDI diesel: Low power and low MPG.

What is the difference between my 1990 166hp 7.3 IDI and all the other 7.3 NA diesels that are rated at 185hp? Can I cost effectively make mine 185hp?

I need more power between 1600 rpm and 2300 rpm.

I’m realistic and would be happy with 10%-20% more power and 1-2 mpg improvement at 1600-2300 rpm. I don’t think I want to go the turbo route, as spending $2000 plus a new pump and a bunch of time isn’t worth it on a $4000 truck,


Questions:

1) I have heard ? that the power difference between 166hp and 185hp motors is in the injector pump. Is it smog related, as this is a California truck? If I got a Baby Moose pump, and the recommended injectors, would that make it a 185hp motor? Would advancing timing to 9 degrees also help at that time? Would I get the power boost I am looking for? At 125k original miles, perhaps a new pump isn’t out of the question.

2) I have heard that when towing, I should just leave the overdrive on. The problem is the truck cannot pull the load on anything other than flat land, so I spend most of the time in 3rd gear, and shifting to 2nd on hills. Would a gear change to 4:56 be a good idea to get the rpms higher so I can effectively have a 4 speed trans instead of a 3 speed trans?


Truck is California 1990 F350 dually extended cab 7.3 166hp diesel, 4:10 Sterling 10.25 rear end, E4OD trans, well maintained with 125,000 miles original, Original injection pump, injectors changed by dealer at about 70,000 miles. Tires one size oversize, I believe 235-85/16, and I think I calculated the tires at 4% greater circumferance. Totally stock, clean truck. Truck runs/starts very well. Also, it NEVER smokes. I always read about trucks with black smoke. None from my truck. I believe motor is in very good condition, and burned ½ quart oil in 5500 miles.

Truck has low power, and low MPG. Empty, it gets 13-13.5 Hwy MPG at 60 mph. Towing my 7’x16’ enclosed trailer/5000 pounds and a small 1500 pound cabover camper (about 12,500 pounds total) it got 10.3 mpg to Bonneville Speedway and back (1300 miles) and was so gutless it was dangerous. Foot near floor pretty much the whole time. Many hills in 2nd gear and 35 mph. One hill 1st gear@ 15 mph. This is normal paved US highway around Ely, Nevada.. Normally, I am described as a grandmother when driving, as I usually get better mileage than anyone I know on any vehicle. Same trip/load with near identical 1990 crew cab F350 dually 460 gas engine/E4OD and 500 more pounds get 8-9 mpg and probably 35% more power.

Since that drive, I did make a small change, as I bought a Ferret meter and timed the injector pump from about 3 degrees BTDC to about 6-7 degrees BTDC. I would have gone to the recommended 9 degrees BTDC, but there was a lot of resistance from the fuel lines, and I did not know how to loosen them.

I have an EGT meter, and temps get to a high of 1100 degrees at wide open throttle on long, steep hill. I have replaced the fuel filter and air cleaner.

I dynod the truck yesterday, and it made 129 rwhp at 3200 rpm. Again, this was after advancing the timing to 6-7 degrees BTDC. Probably pretty strong for a 166hp IDI. Guys in the dyno shop were joking that it was a gas motor, as it didn’t have any smoke at full throttle.

Thank you for any ideas,

Jeff

 

[OLDBULL8]

At 70K miles on the IP and injectors, they should be good yet. You have to set the timing at 8.5 to 9 BTDC at 2000 RPM, then turn up the IP fuel 1 or 2 flats on the hex wrench, if you get too much black smoke at WOT then turn the fuel back a half or one turn. If you have G code injectors, BB codes would be better.

To loosen the IP lines, use a 5/8" wrench on all the IP lines that you can get at, that should be enough to turn the pump, be sure and tighten them again before running the engine.

 

[chris142]

Im new to idi's. What trucks got the low hp engine? First time i have heard of this. Was it a detuned uhaul engine?

My na 6.9 with the timing @8 and a light haze @ wide open throttle is still a **** on the hills. I was grossing about 10k last week and i went up a small but steep hill and i had to drop to 3rd and almost 2nd if it had been any longer. I figure this as normal

 

[icanfixall]

Welcome to the forum. You really need a few things. Seeing you have a timing meter I would tell you to get the timing advanced to 9.0 degree. then see how it runs. If thats still not good enough then replace the injecters and pump. a Baby Moose is a great pump. As for the truck being a 4 grand rig.. no meaning to anything. Fix it so you have what you want. Lets say someone gave you that truck. then you start adding things like a pump and filters and tires. Will you have gone way over the cost to you of the truck. Make it right. Will the rpm reach 3400 or 3600. If it wont then someone may have installed a uhaul pump with the lower rpm limit. Can't really tell you why your hp rating is lower than others either unless it was a high altitude truck with a pump designed for the higher elevations.

 

[bbjordan]

What OLDBULL8 said. He hit the nail right on the head!
Timing is VERY important on these engines.
Pop test the injectors if you have access to a tester. If not, changing out the injectors with a matched set of BBs may not be a bad idea. The whole idea is to have the injectors popping at the same pressure, otherwise the timing will vary from cylinder to cylinder causing it to be difficult to set the timing accurately.

 

[metermatch]

I don't think the rpm was limited to 3200. I just didn't want to overrev the motor. I believe the injection pump is the original one from day one. The 166hp rating is from the decal on the drivers side valve cover.

Jeff

 

[metermatch]

Just a thought on the injector timing: I noticed when timing the engine with the Ferret meter, the timing mark on the damper, aside from being hard to read, was dancing around a bit, perhaps ramdomly moving 1-2 degrees. Is this normal? I am used to gas engines having some amount of movement, and considered this normal.

Thanks,

Jeff

 

[metermatch]

In advancing the timing to 9 degrees, what am I looking for, in terms of sound, performance, or in EGT (I have EGT meter) to tell me that I have gone too far advanced on the timing?

Thanks,

Jeff

 

[yARIC008]

I'd like to know more about this engine too, as far as I knew the 6.9L were 170 HP and the 7.3 was 185 HP. Never heard of a 166 HP unless it was some special International version, but you say it's in a ford.

Edit, I just found another post on another site that mentions some versions of the pump being 166 HP.

http://www.ford-trucks.com/forums/1...-s-w-hp-ratings-complete-idi-tuning-info.html

 

[icanfixall]

Wow... Never seen information like that. Seeing a 7.3 with a 110 hp injection pump is craqzy. Sure were plenty of pumps on our engines.

 

[kas83]

High altitude emissions engine were rated for 166hp, my uncle had a 92 with that setup out in Denver. Between my cousins 83 being rated @ 170 and my 90 @ 185 and the 92, we never could tell a difference when pulling up to the Eisenhower Tunnel. According to his diesel shop out in Denver, the timing curve and fueling of the pump were the difference. Ironically his was the truck that dyno'd the most each time in emissions testing, and he had the most driveline to spin.

Sent from my SCH-R760X using Tapatalk

 

[chris142]

Did they evet use our engines in stationary equipment? Other engines were. They used 6 cyl fords in wood splitters and 318 dodges in forklifts.

 

[FarmerFrank]

Sounds like a catch 22. Low mpg because you have to run the nuts off it to keep up. Like stated, a rebuilt pump to the 185 specs and good timing should help. If you want to keep the R's up maybe go back down to the 215/8516 tires. Smaller tires will keep the rpms up to cruise the same speed. I know 235's vs 215's is 5mph difference at the same rpms in my 86

 

[88beast]

you have an ih based engine not a ford based engine, due to different gearing available, 2 speed rears and a need for a longer life the ih version has a different pump ( some u haul pumps too) with a 3200 or 2800 governor, and a different hp rating. this ip is the only difference a baby moose or other pump will be able to bring your power up, but without a turbo it wont be much of a difference.

 

[mblaney]

In advancing the timing to 9 degrees, what am I looking for, in terms of sound, performance, or in EGT (I have EGT meter) to tell me that I have gone too far advanced on the timing?

Thanks,

Jeff

I have the Ferret timing meter also. I posted questions here about how the timing (using the Ferret) compares to using other meters (like icanfixall rents) and have learned a few things doing mine:

- If your timing light is able to offset then you can use the '0' mark, if not then use a timing tape. I made my own but there are tapes commercially available. This will make it much easier to see your timing mark.

- many (most) timing lights have a problem at 2000 rpm. This is because the light electronics 'switch gears' from measuring lower rpms to higher. I did not notice any difference when checking the timing at 1950 rpm and my timing light was very stable.

- i still have doubts about the Ferret timing accuracy compared to other meters. The Ferret manual states that you should "check the Ferret against a known engine" as a way to calibrate it. This was impossible for me too do so I used it as is and hoped that it was close enough. Opinions here also thought the Ferret was close enough. My truck was noticeably louder when cold, quieted down when off advance but was still gravelly. Two weeks later I lost a glow plug - I have never had a glow plug burn out before. I backed off the timing a bit but now I really don't know what my timing is set at.