Sudden loss of power- inconsistent symptoms

[Wire89]

Hey all...hoping some of you can lead me on to some things to check, ‘03 E350 7.3L. The consistent part is a sudden loss of power on long steep grades. I can enter a grade at a good speed around 70+ mph, it’ll pull well, downshift, keep climbing to about 27-2800 rpm, it’ll sit nicely there pulling along, then it’s as if someone just ropes the back end and she’ll quickly bog down to 45-50 mph. Pedal all the way down, can’t get it to downshift.

Sometimes it will just chug along at 45. Once it dropped all the way to 30 mph. Once there was a burning rubber, brake like smell, in a couple cases the steering wheel just started shuddering, and in a few cases there was a clicking noise that seemed to get more noticeable as the effort struggled. Once the grade tapers off then it’s all back to normal and pulling along.

I can pull over on the steep grade then get on it and will again climb and accelerate to 65-70 mph and sit there until it hits that same wall.

Shallow grades are no issue, I can still accelerate uphill to more than 70. Shorter steep grades are no issue. On the flats it seems to have all the same power, will get up to 80-85 no problem. It’s those linger steep grades where it needs to sit at a given rpm pulling along, that it just gives up.

So far, I’ve only checked all the boots and fittings in the air paths, tightened them all up, looked for leaks. I also wired the EBPV open thinking that maybe it was closing suddenly (lots of grime and soot around the actuator rod). No difference.

[1der]

Do you have a Scangauge? Check for codes?
Boost and/or EGT gauges?

[Bbasso]

Originally Posted by 1der

Do you have a Scangauge? Check for codes?
Boost and/or EGT gauges?

Yup, X2.
While the ECU on the 7.3 is slightly less advanced then more modern vehicles the codes should help to narrow down your problems.
Are you on a stock tune?
Does your rig have any mods?
Is your maintenance up to date?
Knowing is half the battle.

[Wire89]

Originally Posted by 1der

Do you have a Scangauge? Check for codes?
Boost and/or EGT gauges?

No Scangauge yet (been on my list, guess it’s time), no code reader.
I only have EGT and TRANS TEMP in addition to the dash gauges. EGT is normal around 900 on the grades in question.

[Wire89]

Originally Posted by Bbasso

Yup, X2.
While the ECU on the 7.3 is slightly less advanced then more modern vehicles the codes should help to narrow down your problems.
Are you on a stock tune?
Does your rig have any mods?
Is your maintenance up to date?
Knowing is half the battle.

Stock tune, no mods, all service maintenance to date.

[Bbasso]

Drive over to the nearest autoparts store and get them to do the free CEL readings for you. Be sure to write down the #s

[arctictraveller]

I know very little about 7.3s, and their electrionic controlls, but I do know a bit about mechanical diesels. They love to run, and really only need clean fuel and air. Have you changed your fuel filters? Anytime I've experienced a power loss, it's been due to lack of fuel from a dirty filter or bad pump, but that doesn't explain the noises or burning smell. 7.3s are famous for murdering the cam psition sensor though. Sorry I can't be more help, best of luck..........

[rallypanam]

Originally Posted by arctictraveller

7.3s are famous for murdering the cam psition sensor though.

CPS are known for suicide, not for being murdered!

And yeah, check codes, but I'd be thinking fuel pressure.. either pump or injectors/HPOP.

[hogasm]

Torque converter is dying

[Bbasso]

If it the torque converter, pull the dipstick out and inspect the fluid for smell and discoloration.
If the fluid looks shot, dont drive any more and replace that before it takes out the transmission.

What is the mileage on your van?