Ford 7.3 Powerstroke Changed oil runs rough

[klmbranch]

Hello everyone. I just recently picked up a 2000 Ford super duty 7.3 power stroke truck. It has 252k on the odometer. I bought the truck from a wholesaler, so he had no idea of what type of oil the previous owner was using. I've been driving the truck on and off for the past couple of months and it runs great. I changed the oil and the very next day, it started running rough. I used Mobile Delvac 15-40 and a Wix filter. I've had several of these trucks and know that they can be picky on oil,but have never had one act like this. I was just wondering if it is possible that the previous owner had been running a synthetic or a blend, and me swapping back to a 15-40 dino oil could be messing with the injector pressure somehow? Thanks

 

[Danno]

I recommed only running Motorcraft OEM oil filters on Ford diesels. Try an oil filter change to OEM first.

 

[Donald]

Seems unlikely.

More likely bad fuel, temp outside, some connection got messed with while changing the filter and that was un-noticed.

 

[chubbs1]

I doubt the oil has that much to do with it being rough. I have a Sonata and I was amazed how rough it was after the FF. I used PP (a very good oil) and a WIX filter. I read up on it some and found the OEM filter works much better. I switched out the WIX and there was a night and day difference.

What filter was on there when you changed it out? I know plenty of people who use Delvac 15w40 and no problems, I actually feel that engine runs better on conventional 15w40 only exception may be if you live in extremely cold areas of the US and Canada (I'm talking sub zero F)

 

[klmbranch]

The truck had a Wix filter on it. There are no wiring harnesses close to the filter. I replaced the fuel filter when I purchased the truck, and replaced it again after it started running bad. The fuel looks good. I replaced the IPC sensor when I purchased the truck(it was definitely bad). I have always ran Delvac and have never had any issues. The truck doesn't seem to have a dead miss anywhere, but the idle is noticeably rougher after it warms up. I just find it to be a strange coiendence, that it ran great until I changed the oil.

 

[klmbranch]

I'll try a filter change this afternoon and see if it changes anything. Thanks

 

[A_Harman]

Yes, those Powerstrokes use engine oil as a hydraulic link to control timing and quantity of fuel injected. The motor oil can have a big influence on how well the engine runs on first start when the oil is cold. Does the engine "romp" at idle when cold?

 

[klmbranch]

No, it doesn't romp when cold. It starts fine, but the temp hasn't dropped below 50 degrees here yet.

 

[Astro14]

Correlation is not causality. I doubt that an oil or filter change will have any effect on the rough running.

 

[dnewton3]

Originally Posted By: Astro14
Correlation is not causality. I doubt that an oil or filter change will have any effect on the rough running.


To the degree of roughness and trouble caused, I would have to agree.

Yes, the 7.3L and 6.0L use HEUI, and that relies on the oil HPOP to run things (along with a slew of other stuff). So an oil change might make a tiny bit of difference.

Look elsewhere for the cause; the correlation is coincidence.

 

[otis24]

The fuel injectors are affected by the oil/oil filter. I also recommend only using OEM Ford Motorcraft filter. An aftermarket filter that fits poorly can affect the oil pressure, and thus, the injectors. If it has a Napa filter, the Napa filter includes the oii filter cap. Previous owner probably chucked the OEM filter cap. You will need to get a new filter cap.

 

[klmbranch]

Thanks, but this is a 7.3, not a 6.0. It uses a conventional spin on filter.....

 

[roadrunner1]

The filter isn't an issue with an 7.3 as any spin on the proper spec will suffice.

Next OC try a 10w-30 and see if it makes a difference. Those engines are built to run forever with the only weak link associated to your issue could be the cam sensor, they were known to fail.

 

[klmbranch]

Thanks. That's what I just finished doing. I drained the Delvac 15-40 and replaced it with Rotella 10-30(the only lighter weight oil anyone keeps in stock around here). It made a HUGE difference in how the truck runs and idles. It doesn't seem like it is as smooth as it was before the initial oil change, but I may just be being paranoid. The truck came from somewhere up North, so there is a good chance that it has been running on 10-30 it's entire life. I hated to change brand new oil, but it was a lot cheaper than throwing a new set of injectors at it.

 

[bbslider001]

Wow, this is pretty interesting. I have a '97 PSD and it idles a little rough when warmed up. The minute you touch the throttle, it smooths out, and other than the light rough idle, it runs extremely well. I wonder if going to 10W30 for me would help on that. I use Delo 15w40 as well.

 

[mkeenan4]

It sounds to me like you need to add the antifoaming agent. The HPOP in the 7.3 increases the psi of the oil to around 3000 in order to drive the injectors. I was told that when you do that the oil can foam up and cause a rough idle. I can't remember the name of the additive but you should give it a try. If you use the 15w-40 from Motorcraft it has it in it. I highly doubt that the filter is causing the problem as I've used several different kinds with no problems. I can't think of any other reasons that you'd have this issue immediately after changing oil. I always use the Motorcraft oil, $17.24/5qts at Walmart so I don't have to screw with the additive.

 

[951Indy]

Stick with the 10W30. A friend's 7.3 ran so bad after an oil change using 15W40 that he took it in under warranty for diagnosis.

Repair: 10W30 and ran like new.

 

[T-Stick]

10w-30 Rotella T5 runs good in my 7.3 and has good cold weather starts also.

 

[bullwinkle]

I save the 15W40 for the old IDI diesels, for some reason the HEUI Powerstrokes gave me trouble with it too.

 

[jayg]

Originally Posted By: bullwinkle
I save the 15W40 for the old IDI diesels, for some reason the HEUI Powerstrokes gave me trouble with it too.


Would there be any advantage to running the 10w30 in lets say a 94 7.3 IHI IDI motor?

Thanks