I spent the better part of today searching and reading everything possibly related to what I am experiencing. In short, I did my homework, but nothing seems to be exactly the same as my "issue".

I put "issue" in quotes because issues can be mean little *******s and need to be caged, lest they infect other components.

Long story short:

When at idle, the truck (03 Ex. w/7.3) will lope a bit. By a bit, I mean 50-100 rpms every 5 seconds or so. This happens cold, hot, and everywhere in between. She also takes around 3-4 seconds of cranking to start. Occasionally there will be a small puff of white smoke, less than blowing out a drag of a cigarette, but nothing consistent, other than the lope.

Along with the lope comes a shudder. It happens on the up swing, and can be felt through the entire truck. Almost like a miss on a gasser. She gets up and goes, and has no other problems whatsoever. I don't know if I am just being picky, but I would like this to go away. My last diesel was a 94 F250 IDI. That thing never had any issues, and ran great. Maybe I just set my expectations too high.

So. I plan on checking the electrical connections, at the valve cover, and I have shot carb cleaner across every dang tube, pipe, hose, and fitting I could find. I even managed to spray myself right in the face, but that is another story.

Am I stupid, or is there something going on here? AFAIK it had a tune on it, at one point, which was removed. She has a 4" turbo back, an AFE intake, and a coolant filter plumbed in.

I am not afraid to turn a wrench (just replaced the motor in my Tahoe in my gravel driveway) and I am good at drinkin beer. Any suggestions along those lines will be appreciated.

 

The electrical connections along with the 50 cent mod are good for getting yourself familiar with the engine, however, generally speaking you will have a SES light with an electrical issue.

You could have mechanical injector issues i.e. worn poppets or internal orings. IPR's have been known to cause some loping, as well as a biased(oil contaminated) ICP sensor.

 

ICP sensor harness, and plug, are clean. Additionally, there is no change between being plugged in, or unplugged. She only has 125k on her, but I am the third owner, so God knows what all has been fooled with up until this point.

I have not looked at the IPR yet. I am still sifting through all the info to find a nice writeup on cleaning/testing.

 

Here is the IPR rebuild

IPR Rebuild - Large Pics.pdf

 

Thanks, found it about 45 minutes age while searching yet again. I think my laptop is growing into my skin.

From my reading, the IPR is not a usual suspect for strange idle. I say strange because she does not idle rough. Not like a big cam, and not like pulling a spark plug creating a dead cylinder. It is more like the whole truck shakes like a wet dog for one second, then settles down. Maybe a dog is a bad analogy. It is not violent, it is more like a harmonic balancer out of whack, but only for that one second.

I am great at dealing with big issues: the drive shaft fell off, head needs to be pulled, etc., but little things like this drive me crazy!

 

Well this is just dandy.

I farted around under the hood for a bit today. Re-seated connectors, wiggled things around, and generally got dirty. I also added a half can of Seafoam to the oil. I fired the truck up, and it is idling perfectly.

I am not celebrating just yet, as it may be a fluke, but I am hopeful that my hamhandedness may have jarred something loose. I fully expect to have the same issue tomorrow, so ya'll can offer suggestions.

 

I havent heard or read anything good about sea foam, but the fact that it changed when you added it makes me think its oil related. I'd take a look at possibly cleaning the IPR and checking the o-rings on it just to potentially rule it out. Do you have a way of datalogging it?

 

Seafoam, Lucas, and Marvel Mystery Oil can be a Godsend for stuck lifters and water intrusion issues. I just had about 6oz. left over and dumped it in. 6oz. will treat approx. 5 quarts of oil, and she just had a full 15 qt. change. I really don't think that the Seafoam fixed anything, there simply wasn't enough to make any kind of a real difference IMO.

I think that I probably did something when re-seating connectors but, since I touched all of them, I have no idea which one may have been the culprit. I believe that I will go out there this morning, only to find that the problem is still there. I am contemplating buying the AE system as I do not believe in throwing parts at a problem, nor in paying stealership prices.

 

What oil are you using ?? and how long since yor last oil change ?

I ask because when I changed from Shell Rotella 5-40 synthetic for winter back to regular Shell Rotella 15-40 for the summer months , my truck takes a little bit extra to start and also seems to have a different idle to it . I would think adding a can of Seafoam or whatever to the oil would help clean the injectors if they were starting to get gummed up from thicker oil in it .

That's my thinking , but I'm probably wrong .

Maybe someone will straighten me out !

 

Literally changed the oil 3 days ago.

The issue is back this morning as I knew it would be. There was no way she was going to let me fix her that easily!

Currently running Delo 15W-40. Did the same thing with Rotella T 15W-40

 

My 02' F250 Has a very slight ( maybe 50 RPM) up and down surge when at idle...it's always done it, at least for the last 100K.

 

Exactly where I am at. I have never heard another one idle like that, and I pay attention when a PSD starts up, but it is nice to know that someone else has the same thing.

 

I agree, I own alot of 7.3's and this is my personal DD, mine is the only one that does it....if you ever figure it out, i would LOVE to know what it was!
i can attest though that it hasn't affected the reliability or performance of the truck at all so far.

 

I took a long weekend on the boat (Fri-Tuesday) and have yet to poke around anymore. The in-laws are coming on Monday, and the Wife is bound an determined to see me clean up my Tahoe project. On a positive note, she is probably going to get me an AE for my birthday next month so, hopefully, I will have some solid data to work with!

 

I have exactly the same problem here too. I have been searching the forums and I see it a lot, but never a solution. I have changed everything you could think of from IDM to all new injectors from DP, even a PCM about a year ago. UVCH on both sides when doing the injectors and glow plugs. EBP sensor and tube replaced, IPR replaced and the connector. I have tried several CPS's and even tried different weights of oil as well as synthetic and fossil. I have run it on my EA and even had a really good Diesel Tech look at it, he had no clue.
Tomorrow morning I am trying the fuel pump. I am open to any suggestion.