i have a 86 f-350 with the 6.9L and it doesn't seem to have the power it should. when i got it the timing was retarded and i timed it by ear with some noticible improvment. i am pretty sure the fuel screw in the IP was messed with and i was wondering if there is any way to tell where the screw needs to be.
IP question
- Thread starter Ford4life
- Start date
Diesel JD
Full Access Member
Well there is no right or wrong place to have it unless you mean stock. Are you getting really excessive black smoke or a serious lack of power on the other hand? Better yet would be a pyrometer.
Cat_Rebel
Does not compute
My rule is to back it off till it don't smoke no more. I had mine turned up so that you couldn't jump on the highway or pull a trailer without leaving a trail of smoke & getting bad MPG. I just backed it off (maybe little less then stock) & now I don't even hardley get a haze pulling a trailer or getting on it hard. The MPG went back up & temps are cooler, don't see that much diffrent power wise either.
Diesel JD
Full Access Member
Theres no good reason to turn up the fuel unless the truck at least has a turbo or other extensive air intake mods and a pyrometer. Short of a pyro the lack of a serious amount of black smoke is a good indication that the calibration is right.
Cat_Rebel
Does not compute
I have a pyro on mine up by the manifold I don't think I even hit 1200* most I ever hit was 1150* but without a turbo it climbs up there in a hurry!
there is no smoke at all. what concerns me is that the truck doesn't seem to have great power climbing hills on the highway. on an even moderate hill you have to shift down and the best you will get is like 35 or 40 mph. i don't know if this is normal for this engine or what? the truck has a steel flatbed with dump hoist and has my big welder/generator and tool box mounted on it, could the extra weight be the problem?
Cat_Rebel
Does not compute
Not sure if that welder is helping it any but it should be able to move itself. Might want to look into a more free flowing muffler for that truck & check your air filter & change your fuel filter if you haven't for awhile. Just trying to throw some ideas out there. Does it start up alright everyday?
LCAM-01XA
Full Access Member
Mine is turned up 90 degrees at the screw (so a flat and a half) and when empty during normal driving it don't really smoke at all, now if I floor it when in OD yeah, she smokes good, but I can still get decent acceleration and hill climbing without any smoke at all. Towing a 2000 lbs trailer, now that's a different thing, on light uphills or flats but at higher speed there's some haze out the stack, trying to maintain high speed on a decent uphill makes it smoke good, but I just let it lose some speed and it's good with just a slight haze again.
truck starts right up every morning. it does however, have one of those cheap universal mufflers on it that the last owner put on. i was debating losing the muffler all together and going with dual exhaust out the back. the fuel filter is less than 6 months old and air filter seems clean enough. its frustrating because i love the truck and just wish it had a little more umph on the hills.
Diesel JD
Full Access Member
Depends on a lot of things, how hilly we're talking about and how heavy your truck and tools are. I've never had this kind of problem, if you have really tall gears like 3.31s or 3.08s or some oddball gears like that it will be more of an issue. If its 4.10s or 3.55s it should handle a light load in your tallest gear at 55-60mph no problem. When I say light I mean anything under 2-3000 lbs. Over that is heavy which they can handle just don't expect to keep up with the gassers and new diesels in that case.
mankypro
Learning Slowly...
This is exactly what I'm feeling in my NA 6.9. I suspect messed up injectors and or the IP. I'm going to mess with the screw on it see if I can do away with some of the smoke.
I stand on it to get it to move sometimes. And I get clouds of black smoke. I'm wondering if the high altitude (1 mile high) has some effect on it. And I'm wondering if I should retard my timing.
I stand on it to get it to move sometimes. And I get clouds of black smoke. I'm wondering if the high altitude (1 mile high) has some effect on it. And I'm wondering if I should retard my timing.
LCAM-01XA
Full Access Member
high altitude is a killer on naturally-aspirated diesels - you're obviously dumping in too much fuel for the amounts of air you're moving through the engine. First thing that comes to mind about that - on a 6.9 you can use the 7.3 intake housing, the opening where it meets the engine's intake plenum is much much larger than what you got now so it flows more. You also may wanna keep the 6.9 cover lid, as it don't have that "soup bowl" inside it the 7.3 lid does.
mankypro
Learning Slowly...
My air filter top has the bowl in the middle.
Of concern also:
Smoke analysis
White smoke: Caused by unburned fuel passing through the engine. Some white smoke is normal on cold start-ups.
Excessive white smoke could be an indication of inoperative glow plugs, loose injectors, low compression from worn rings or bent connecting rods, or coolant leak into the cylinders. Black smoke: Caused by excessive fuel for the amount of air drawn into the cylinders. Some black smoke on hard accel or at higher altitudes is normal.
Excessive black smoke could result from restricted intake or exhaust, inoperative leaking or weak turbo (if equiped), intake manifold gasket leaks (turbo), leaking or worn injectors, fuel return or supply restriction, advanced injecion pump timing or defective injection pump. Blue or blue/white smoke: Caused by insufficient fuel or oil consumption. Normal when engine is cold or idling for extended periods.
Excessive smoke could be caused by air in the fuel, contaminated fuel, loose or plugged injectors, thermostat stuck open, oil consumption, plugged crankcase depression regulator valve, retarded injection pump timing, or defective injection pump.
Of concern also:
Smoke analysis
White smoke: Caused by unburned fuel passing through the engine. Some white smoke is normal on cold start-ups.
Excessive white smoke could be an indication of inoperative glow plugs, loose injectors, low compression from worn rings or bent connecting rods, or coolant leak into the cylinders. Black smoke: Caused by excessive fuel for the amount of air drawn into the cylinders. Some black smoke on hard accel or at higher altitudes is normal.
Excessive black smoke could result from restricted intake or exhaust, inoperative leaking or weak turbo (if equiped), intake manifold gasket leaks (turbo), leaking or worn injectors, fuel return or supply restriction, advanced injecion pump timing or defective injection pump. Blue or blue/white smoke: Caused by insufficient fuel or oil consumption. Normal when engine is cold or idling for extended periods.
Excessive smoke could be caused by air in the fuel, contaminated fuel, loose or plugged injectors, thermostat stuck open, oil consumption, plugged crankcase depression regulator valve, retarded injection pump timing, or defective injection pump.
Diesel JD
Full Access Member
Yep you need a turbo at those altitudes and you need to keep a good eye on the EGT gauge. If you were at sea level you'd never have this problem. Here in FL the lay of the land is usually very flat and of course we have no elevation. My C6/4.10/ NA 6.9 setup was great, it would do anything I asked of it without a whimper but it would be screaming against the governor at 68mph and even 60 had a lot of cab noise. I traded some power for lower RPMs by swapping to a set of 3.55 gears from a member here and the power was still there but down a bit compared to the 4.10 gearing. Last year I added an ATS non wastegated turbo and man it was a different truck, night and day I tell you. I still hated the auto trans, so this year I took on the ill advised task of swapping to a manual just cause I like them better and simpler, hopefully better fuel economy. It gets up and goes better yet with the manual, hope soon to add an overdrive of I can find a way to adapt it. Back on topic, you're power in a 6.9/7.3 is dictated by your fuel setting and how free flowing your intake and exhaust is. If you're N/A you should at least cut out the soup bowl and have a 2.5-3" free flowing muffler and exhaust, if you have a turbo you want at least a 3"(true three inch, no non mandrel bends!) Also a tired IP is often part of the problem when these things don't perform to expectations. Altitude is bad on NA diesels basically you either need to defuel them(which will save the motor but make the truck even lower on power) or turbocharge which is a better option.
