SES light intermittent no codes now what?

[mr_onmyway]

SO this weekend while driving around town the Service Engine Soon light came one and I noticed the truck started running rough while running down the freeway under light acceleration. All through the weekend it came and went sometime just giving a bit of gas and the light would go off. Sometimes it would take awhile (1-2 minutes) I took it over to Schucks to have them read the codes and their tool said passed. I drove out of the parking lot and got on the on ramp and under heavy acceleration the light came on again. and then went out after a few seconds. went back to schucks and without shutting the truck off I had them scan again and no codes again.

I did an oil change on it before that thinking maybe the oil was foaming or something causing an injector issue but all this occurred after that as well..

Any Ideas?

[late_99_PSD]

Does it run fine at an idle? Did it ever shut off or just run ruff? When was the last itme you changed your fuel filter? Does it happen at a certain RPM? Does it still get decent milage? Does your truck have a cat, if so mabey it's clogged. How good of a scan tool do they have? Can it read you backpressure? If yor cat's clogged then you'll read a high backpressure. My first thought was oil but you said you chaned that. Could be a weak HPOP. Giving you Q's then A's, sorry. Hopefully someone else has had your problem and will chime in.

[mr_onmyway]

It runs fine at idle unless the ses light is on.
I need to check my book to see about the fuel filter. But I know its been over 10K although I also drained that tonight as well but didnt get it into a jar so I dont know if there was water/junk in it.
Its never shut off when the the ses light was on or off.
I have yet to pinpoint it to a certain rpm as I have seen it happen just off idle as well as under full throttle with the turbo spinning.
Still decent MPG around 14-16. Under heavy load 10-11.
No Cat.
the code reader was an actron. I ran up to another shop in town and they had the same rearder. They claim they can only read the code if the ses light is on. of course since its intermittent I cant get it to occur in their parking lot.

[Highwaywrench]

I just went through the same thing with my 01 550. Get this

It took forever to throw a check engine light. when it finally did, it felt like crap, and wouldn't pull 40 km/h downhill with a stiff breeze. A budgie fart in front could have stopped it.

So, I limped it home, and got under the hood, by wiggling the wires to the valve cover connector on the left bank, I was able to make the problem come and go at will.

Today, I pulled the left cover, and the connector had come loose. So, I spent the time and money, got new glow plugs ( it needed them ) and new gaskets and UVCH. Did the 50 cent mod to them while I was at it, and its all sunshine and smiles again. ( for 24 feet or 24 hours, whichever comes first. such is the nature of the beast )

Just food for thought.

[mr_onmyway]

whats the 50 cent mod? Are the wires on the back of the valve covers? I will go out and poke around once it gets light out.... thanks for the ideas1

[mr_onmyway]

I checked my book and either I didnt write down the last fuel filter change or it has been in there 25K. I searched around to see what the change interval is on these but didnt find it. does anyone have a link?

[mr_onmyway]

Another symptom showed up tonight. driving home from work at around 50 mph. not accelerating just cruising along with the cruisecontrol off and the ses light came on and the engine shut off. pulled over truck started right up and drove the rest of the way home.

[jesilvas]

Possibly CPS. Ever had it done under the recall?
Fuel filter should be every oil change or every other. I usually do it about every other.
idk what Shucks is but if they don't specialize in diesels, I doubt that their scanner is good enough to pull codes.
Well ask them, what about codes when the light isn't on? If they say there's no such thing they are lying. There are plenty of codes that'll throw without a light.
I think by the 50 cent mod he meant the 10k resistor mod. Or 5.6k. Or whatever you put in there. There's a write up in the mod section for the 7.3s.
If the filter has been in the for 25k change it now.
What kinda oil you use? If it's the same stuff you been using that's not it.

[mr_onmyway]

nope never had the cps recall done, in fact the wife put the paper on my table earlier today along with the speed control deactivation switch recall so I can try and get the rig in. Most of the places said they can only pull codes if the light is on. But I am almost positive that I know the codes are saved.

the oil is rotella t syntetic 5-40 and yea I am running out to get a fuel filter as well.

[jesilvas]

Might very well be the CPS. They do weird things when they start goin. Mine would just up and die a few times or almost die then come back to life.
Yea they don't know what they are doing. If they don't know diesels, then run away
The oil shouldn't be the problem them. That's some of the best stuff to run according to a few tests.