Smoking and rough running.

[hoptwoit]

2003 f 350 7.3 liter manual tranz no mods.
When coasting down a hill (foot right off) if you try to add power the engine pops and bucks. lots of smoke. Then it will straighten itself out again. It seems to idle well but in nutral if you rev it up it starts smoking and gets rough right @ 2100 rpm. Disconected the icp and it seemed to get worse. Any ideas?

[RadarRider]

Originally Posted by hoptwoit

2003 f 350 7.3 liter manual tranz no mods.
When coasting down a hill (foot right off) if you try to add power the engine pops and bucks. lots of smoke. Then it will straighten itself out again. It seems to idle well but in nutral if you rev it up it starts smoking and gets rough right @ 2100 rpm. Disconected the icp and it seemed to get worse. Any ideas?

It's sounding like it's fuel related. Have you scanned for codes?

[hoptwoit]

There are no codes. I have checked the fuel pressure and it is in spec.

[Spinal Tap]

Is it cold there? Water in fuel? Gasoline?
What color is the smoke?
Does it clear up at idle?
Does the truck have any power at all?
Tack work at all?

Coasting down the hill, it pops more foot on or off?

If it clears up at idle, how long does it idle good for,.. as in does it stumble, go crazy for a few seconds, sound like its running on 6.

We need more info

BW

[hoptwoit]

The truck has 235000 KMs on it or 150000 miles.
The engine starts well and idles very smooth. It passes all koeo tests. it passes cylinder contribution tests. The outside air temp is usually around -10 to -20 c but it did it previously at warmer temps too. All the symptoms I describe are with the engine warmed up oil temp above 170 f. The smoke is white and I believe it is unburnt fuel. I thought it could be an oil issue so I changed to rotella T15 w40. before i changed I did the oil aeration check here are the results: @3500 rpm the initial ICP pressure was 1900psi then after 30 seconds it slowly dropped down and went to 1630 and stayed there. This seemed a little funny to me but I have nothing to compare it to. When i ran the test it showed an ICP voltage higher than expected. 2.25 volts. The book values for my unit are 1800 psi max after 3 minutes 1.75 volts max. @ an icp pressure of 1800 my ICP voltage vas more like 2.1 volts. Some days it seems to be really bad other days not so bad. The exhaust sytem is gutted. The backpressure device seems to be working correctly. I do have a small leak at the up pipes to the turbo but can still get 17 psi under load up hill.

[hoptwoit]

when you are driving the truck if you try to slowly accelerate the engine will get to 2200 then start to miss and run poorly. Add throttle gently and it gets worse. Floor it, it misses a little then once it hits 2500 rpm it puts you back in your seat and quickly reaches 3500 rpm and governs out. I dropped both tanks and cleaned the finger screens in the pick ups. The filter was changed recently there does not seem to be a fuel contamination issue. Did not have any gasoline misfueling. No water in fuel

[hoptwoit]

2003 ford F-450 Manual transmission. No performance mods. The engine has 234000 kms on it. While driving When the engine is acelerating it gets to a rough spot between 2000 and 2400 rpm. If you are easy on the thottle and don't force it to accelerate hard, the engine smokes and runs rough. If you floor it it seems to do a little better. It still smokes a little but once past 2500 the engine pulls strong to 3500 and governs out. Here some numbers I recorded.

The following numbers are taken while stabilised at the stated RPM. In neutral no load.

Readings at Idle.

ICP duty cycle. 10.94
ICP volts. 0.71
ICP pressure. 475 PSI
Mass fuel desired. 11.65 Mg
Volume fuel desired. 14.0 cc
Barometric pressure volts. 4.22
Exhaust back pressure PSI 13.7 PSI
Manifold absolute pressure. 13.4 PSI



Readings @ 2400 rpm.

ICP duty cycle. 21.09
ICP volts. 1.78
ICP pressure. 1300 PSI
Mass fuel desired. 14.38 Mg
Volume fuel desired. 18.0 cc
Barometric pressure volts. 4.22
Exhaust back pressure PSI 18.27 PSI
Manifold absolute pressure. 14.8 PSI
Injector pulsewidth. 1.77 ms

Readings after trying to accelerate from 2400 to full throttle the engine will acclerate to 2600 then the smoke starts, the fueling seems to increase greatly ICP pressure too high the engine begins to smoke more the fueling continues to increase the RPM decreases to 2350 RPM.

ICP duty cycle. 29.7
ICP volts. 2.65
ICP pressure. 1983 PSI
Mass fuel desired. 33 Mg
Volume fuel desired. 38.0 cc
Barometric pressure volts. 4.22
Exhaust back pressure PSI 18.78 PSI
Manifold absolute pressure. 15.7 PSI
Injector pulsewidth. 1.88 ms







Wide open throttle 3418 rpm jumps up and down and smokes a little but much less than the readings just above.

ICP duty cycle. 30.0
ICP volts. 2.75
ICP pressure. 2025 PSI
Mass fuel desired. 24.38 Mg
Volume fuel desired. 29.0 cc
Barometric pressure volts. 4.22
Exhaust back pressure PSI 25.0 PSI
Manifold absolute pressure. 20.4 PSI
Injector pulsewidth. 1.99 ms

There are the numbers to me it looks like the ICP pressure is too high and the mass fuel and volume fuel go way up when the smoke starts. Is this a PCM issue has anyone seen this before ?

[hoptwoit]

Drove truck again today and it was hardly acting up at all. Drove much better. Put the computer on again and found the mass fuel volume fuel desired did not go over 24 cc and 22mg. ICP @ full throttle went to 1800 and stayed there. All seemed ok then is began to act up again and same as above mass fuel and volume fuel went way up ICP pressure went way up 2200psi and the smoke.

It seems that the PCM is commanding the high fuel flow my question is why is there a sensor that would cause this or is it a PCM issue.

[Fire Mechanic]

What was the solution? I'm having similar problems.

[hoptwoit]

Did a compression check and found cylinders 6 and 8 were at 325 psi all others were 425 or better. Pulled the engine and put in one from a wrecker with 32000 kms on it. Did the ISTP regulated fuel return and high pressure oil crossover pipe. also did the DIY cold air intake. New engine has run very well for 40000 kms now. Also did the road valve mod instead of PCV. Note : PCV system only, Pull your oil fill cap with engine at idle if there is any and i mean any gasing from the oil fill you have a blowby problem.