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Discussion Starter #1
1997 Ford F-350 7.3 289,000 Miles ZF

So I’ve got a slight miss in the service truck , it seems to happen when pulling up to a stop light . Power seems ok going down the road .
I ran a cylinder contribution test and found no codes . I took a infrared thermometer to each exhaust port and the rear three cylinders on both sides where a lot warmer so I attributed that to the fan blowing on the engine. I checked the external valve cover harnesses for burned pins connectors looked great .
I might pull the valve covers and look at the oil discharge when hot , I’ll also check fuel pressure.
One thing that I’ve noticed which could possibly be my imagination is ever since the last service the engine does run as smoothly as it normally does which I attribute to the choice of oil I used . I’m not going to start a oil war but I’m tempted to change the oil and see what happens. I still lack about 2000 miles before it’s due though . Fuel filter has maybe 800 miles on it .
Looking for any ideas or thoughts .


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Is it full of oil? Not a quart low, not a half quart low, but full? If not fill it and see if it stops acting up. If it IS FULL, try running it a quart over full. That's where I would start.

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Discussion Starter #3
I’m pretty certain it’s full , I’ll have to check it tomorrow when I get to a flat spot .
It’s got a sort of uneven idle to it , like it’s surging . I think the IPR is on its way out . When it’s cold it runs nice and smooth, no surge . The idle will fluctuate a 150-200 rpms. For as many miles as it has the truck runs pretty good and has good power considering it’s almost 10,000lbs .


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I had A miss but only while the cruise was set it turned out to be the cps. installed a new Ford unit and my miss was gone.
 

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My 96 is doing that same thing, and it's the IPR and/or HPOP, I'm gonna change them both shortly and I'll Let you know if it cures my problem. Mine also throughs random oil pressure codes also though, and will stall but fire right back up.
 

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Discussion Starter #6
The cps is a year old , it’s the factory ford purple unit . I was getting a shudder when the windshield wipers were on .
I’m wondering if The HPOP is getting worn out myself. Let me know what you find out heavydoc.


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Will do, gonna try and replace it this weekend, I said the same thing last week to though. Haha
 

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Sorry just re-read original post.....

Slight miss or run rough upon idle down, like at a light can be a number of things in my opinion.
With some engine oils my trucks would run rough, especially getting close to change out.
Might be CPS on the way out, but I’d say unlikely unless has had random shut downs.
Could be IRP needs a rebuild kit and or new HPOP, I’d do IRP rebuild first, prior to swapping pump.
Check the ZF5 transmission could be the dual mass flywheel going out which will make run rough in above condition. Should be under 3/4” play (rotational play) between dual mass flywheel, more and you’ll need to replace and get a single mass one... I’m betting it might be this.
You could also clean the fuel bowl regulated return fuel screen.

How long has this condition been happening?
Have you made any recent changes to the truck, different oil, fuel, not running fuel conditioner?
j
 

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Discussion Starter #11
Sorry just re-read original post.....

Slight miss or run rough upon idle down, like at a light can be a number of things in my opinion.
With some engine oils my trucks would run rough, especially getting close to change out.
Might be CPS on the way out, but I’d say unlikely unless has had random shut downs.
Could be IRP needs a rebuild kit and or new HPOP, I’d do IRP rebuild first, prior to swapping pump.
Check the ZF5 transmission could be the dual mass flywheel going out which will make run rough in above condition. Should be under 3/4” play (rotational play) between dual mass flywheel, more and you’ll need to replace and get a single mass one... I’m betting it might be this.
You could also clean the fuel bowl regulated return fuel screen.

How long has this condition been happening?
Have you made any recent changes to the truck, different oil, fuel, not running fuel conditioner?
j


The truck sat for a few years then I acquired it from some horse trading .
I rebuilt the IPR before it was put on the road .
I rebuilt the fuel bowl and cleaned the screens , replaced the fuel lines as well as the lift pump . The HPOP was removed and resealed as the “ non serviceable” plug was leaking as well as the mounting gasket .
The truck has always had the weird up and down idle sure before all of this and after . The cps is a new ford purple unit as well .
The clutch is a LUK solid conversion.
This last oil change I used different oil then I usually use and it seems to not run as well .
I’ll go back to my normal oil this next interval and see what happens .
I’ll say this , the truck does have injector siction after it sits a while and has been run . It’s annoying when you’ve got it to the floor and it won’t accelerate, but once it gets to 2900-3300 rpm it comes alive like a light switch . I think the IPR is tired .


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Ok gotcha, I’d give the oil change a try. In a number of truck I ran Delo 400 15w-40 and 10w-30 (winter) and when I neared oil change they’d idle rough, like noticeable difference. Then went to Mobile One full synthetic with a by pass oil filtration system and that engine ran smoother. Last couple trucks I’ve ran Rotella T4 15w-40 and 10w-30 (winter) with a Donaldson DB 7405 (much larger Cat filter in stock location) and trucks seem to idle good, (which might be Tuning as we run Hydra tuners).

In respect to low felt power try unplugging your MAP sensor harness, (on fire wall passenger side above heater box). If truck runs better then possibly MAP sensor is gone.
j
 

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Discussion Starter #13
Ok gotcha, I’d give the oil change a try. In a number of truck I ran Delo 400 15w-40 and 10w-30 (winter) and when I neared oil change they’d idle rough, like noticeable difference. Then went to Mobile One full synthetic with a by pass oil filtration system and that engine ran smoother. Last couple trucks I’ve ran Rotella T4 15w-40 and 10w-30 (winter) with a Donaldson DB 7405 (much larger Cat filter in stock location) and trucks seem to idle good, (which might be Tuning as we run Hydra tuners).



In respect to low felt power try unplugging your MAP sensor harness, (on fire wall passenger side above heater box). If truck runs better then possibly MAP sensor is gone.

j


I’ve thought about getting the cat oil filter but I often travel off road due to my work so I’m pretty sure I’ll get that filter torn off lol .
I typically use Walmart super tech 15w40. This last interval I used NAPA 15w40 . I’m not pleased with it , which is surprising as I’ve never had trouble in anything I’ve run it in before.
As often as I change the oil in the truck ~ 6000 mile intervals I buy cheap oil . I do however use a motorcraft oil filter .
I’m pretty sure it’s injector stiction . After that first bout of poor acceleration it’s fine and it will run great .
I’d like to find a test IPR and HPOP and try swapping them , anyone have a loaner ?


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I will once I buy my adrenaline hpop for my 02, my spare is going in my 96 then sending that in as a core for my 02
 

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I’ve thought about getting the cat oil filter but I often travel off road due to my work so I’m pretty sure I’ll get that filter torn off lol .

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Donaldson DB 7405 just sticks down flush or slightly passed the engine cross member, for the most part flush with the pan sorta. Front drive line and axle will protect filter along with the pan and cross member. If you’re dragging it on the oil pan in mud gravel... probably not recommended. Take the ATV, SxS, then you can charge that out for work too, that’s what I do.
Cheers,
j
 

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Discussion Starter #16
Donaldson DB 7405 just sticks down flush or slightly passed the engine cross member, for the most part flush with the pan sorta. Front drive line and axle will protect filter along with the pan and cross member. If you’re dragging it on the oil pan in mud gravel... probably not recommended. Take the ATV, SxS, then you can charge that out for work too, that’s what I do.

Cheers,

j


Atv sxs lol . I wish brother . I use the truck to do service and repair on machines and equipment, typically broke down in the woods or a pasture. The last off road repair was pulling the engine on a hitachi ex100 track hoe . Good times


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Discussion Starter #18
Well I finally got around to checking my oil yesterday, it was everything bit of a quart low . I topped it off and ran it . I didn’t notice the slight idle miss when pulling up to a stop light . There was some erratic shaking of the engine at times so I’m thinking it’s mostly electrical ( IPR , ICP) .
I’ll have to save some money and buy some motorcraft parts .
There is oil in the icp connector as well .
It’s a good running truck considering it’s previous life and it’s current one .


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Glad you are making progress! I've not personally messed with an icp sensor yet, but from what I've read around it or the pigtail could be contributing to the erratic running. I think to test it you just unplug it and see if it runs better.

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