I'm going crazy, and broke, trying to figure out what's wrong with this thing:
2000 F250 7.3L ZF 6spd 4x4 regular cab long bed 253k
DP F6 chip, 4" exhaust, WW2, EBV delete
I run 5w40 Rotella Synthetic. Oil was changed about 1,000 miles ago. I also added a quart of Hot Shot stiction eliminator
I use Power Service and Stanadyne lubricity in every tank. Fuel filter is new.(motorcraft)

For a month or so its been acting weird. I get a stumble/miss/stutter, at random, but mostly under hard acceleration and high rpm (specifically approx 2500-2800rpm). It will also do it on decel when I lift after accellerating . Recently, I noticed it is also idling roughly. The engine is shaking and it feels like a miss. When it does its "thing" it sounds like a single "knock". Occassionally, it sort of sounds like an injector "buzzing". I've been using the "stock" tune for the last few weeks, to minimize any chance of engine damage, as I have to drive it. Turning up the chip makes the problems more noticeable and happen at a lower rpm. The truck has plenty of power, and pulls hard, except for the "stutter". If I hold my foot in it to "push through" the initial stumble at 2500 or so, it will keep going a few hundred more rpm, and then really start bucking.

There are no meaningful codes. I DO have:
EBV related soft codes - makes sense since its deleted.
Overboost related codes- from turning the chip up - won't happen in stock setting
A soft code for the back pressure SENSOR. I have a new one and will be cleaning the tube when I get a chance. I unplugged the sensor and it made no difference in the miss issue.

I have recently done the following in pursuit of a solution to all this:
New IPR (autozone) valve and pigtail
New ICP (motorcraft) and pigtail ( sensor had oil in it)
New CMP and pigtail. (2 actually. First a standard pc139 for the obs, and currently a Napa echlin correct for '00) No change. Although it initially had the dreaded Ford small head light grey sensor and failed cct for #3 & 8. After the cps change, it passed cct.

Accellerator Pedal Position Sensor. It would not read any higher then 3.95v at wot, and only 0.50v at idle, so I installed a new one. After adjusting it a little, I have 0.76v at idle, and 4.02 at wot. Didn't affect the stumble issue, but it seemed to greatly improve/eliminate my parking lot speed "bucking".

I just did the UVCH's. The passenger side was pretty much unplugged. But they all looked good. No burnt, melted,or chafed wires anywhere. I probably could have just plugged it back in, but I changed both sides with new Motorcraft parts anyway. I did the gaskets and the uvch, but not the engine side harness/pigtail, as they looked ok. I also did the 0.50 mod as a preventative measure. After seeing the unplugged harness, I really thought this would be the end of the problem, but its not. Very frustrated.
As a side note, I was surprised to see that I have 8 AD injectors, and not an AE in cyl 8.

I have an old outdated snapon scanner. Its only good up to '99, but I am able to scan my 2000 as a '99. I think I'm missing some pids though.
I can do cct and buzz test, but no PERDEL readings.

As far as ICP, it idles at about 450psi, at approx 12% IPR dc. On a brief 2nd gear wot run, it will hit (and hold as long as I have road to stay in it) a little over 2900psi, at 41-42% IPR duty cycle. I did notice, during these near instantaneous stumble events, ICP would flutter on the scanner about 75-100psi. Its almost too quick to even see it.

Please help.... This is my only vehicle at the moment, and I need it to run right. I can't just keep spending money. I need to figure out what the problem is.

 

Bucking - that can be a few things, and it's usually fuel related:

• Air in fuel (See - Hutch mod)
• Bad injector O-rings (Is your fuel filter black?)
• Loose injector (Did you check the injector bolt torque while you were in there?)

An aftermarket IPR may also be your bane, but I would look at other issues first, since the problem was there before and after the new IPR.

The knocking is consistent with air in fuel and loose sticks. That AE was a patch over the real problem (air in fuel), so it's OK to have an AD in there.

It's smart to run the truck in stock mode, but you'll be better off pulling the chip. You want to troubleshoot the truck in it's raw form, with the fewest possible variables.

I don't suppose your scan tool can log and export the log, can it?

 

Had same issue and it was a short in a wire harness.

 

Can you expand on which portion of the wire harness impacted you and how you found it for the benefit of all the readers?

 

1.) Air in fuel. I am aware of the hutch mod, and its on the list of eventual mods. However, millions of these things run just fine without it, so I shouldn' "need" to do it just to get it to run normally. Also, why would it "hiccup" or knock on decel, if its air in the fuel? Under a coast down zero throttle position, it shouldn't be injecting any fuel, aerated or not. Yet, I will get a stumble/knock under those conditions. Also, could it really be pulling that much air in to IDLE rough? Also, the truck has a filled to the brim full tank right now, and it still does it. Admittedly, its always seemed to be a little stronger with half or more in the tank, vs 1/8 of a tank that I usually run it down to before filling.

2.) O-ring leak. Hmm, the filter was, if I remember right, perhaps a little darker then I thought it ought to be, but not "black". The fuel I drained from the bowl certainly wasn't discolored. If I really had a leaking injector o-ring, wouldn't it show in the icp/ipr dc? I was under the impression that the numbers I'm seeing are pretty good. As I said, it pulls hard, including in the higher tunes, right up until its little hiccup. No smoke, black or white.

3.) Loose injector. Yes, I checked/torqued them all, to 125 in-lbs. Driver side were fine. Passenger ones, I got maybe a 1/4 turn of the wrench out of each one. I also torqued the glow plugs. One on the passngr side was loose. I torqued the rocker pedestals to 210in-lbs, as that's as high as my small torque wrench goes. They were fine.

I really don't want to "mess" with the chip, and I doubt its the problem, but I might pull it later in the week.

I have an old mt2500 red brick scanner, so no data logs. What parameters are you interested in seeing?


Honestly, I'm still leaning towards something electrical. It sort of has that kind of feel to it. I'm just not sure what/how to test from here. Could the mostly unplugged passngr uvch fried the IDM?

Just so frustrated. Its been a month plus fix fest on this thing. Started with rear springs/hangers, then front diff/suspension rebuild, then I just got done rebuilding the turbo ( a nightmare in itself- mine was trashed and it took me 4-5 days just to find a core) with a new ww2 and dorman up-pipes, now this.I would say I've spent close to $3,000 on this thing in the last month or so. My Buckzooka barrel is red hot and "shot-out". Time for a cease-fire

 

I got pissed off at it, and ran it with the 80hp DD tune on my home last night. Actually seemed a little better, but was still definitely hiccuping. It will do it at random at any rpm, and/or any throttle position ( in both stock or "tuned" modes)

OK, so I put the scanner on it again when I got home from work.
First, ICP is around 450psi, at 10%IPR DC, at idle

It definitely has a miss with a lopey idle. Not so much cold, but very noticeable after a good hard 30 miles or so of driving- basically everything fully warmed up.

Second, and much more important, I now have 2 codes:
P1670 EF feedback signal not detected
and
P0275 Cyl 5 CCT fault.

So, I'm still barking up the electrical tree. I found a few diagnostic flow charts online , to address the P1670, but they are clear as mud. They refer back to breakout box pin#'s. Ok, great but I'm not a dealer tech with access to stupid expensive proprietary test tools. Where and what do I test? Do the breakout box pin #'s equal the pin numbers on the actual plugs?

Since this P1670 indicates a communication fault between the ecm and IDM, is that covered by the engine valley harness that is often found to have chaffing and shorts? If so, would I cover any possible locations of this wiring issue by just going ahead buying a new engine harness from Ford (This goes from the 42 pin connnector, through the valley and includes all engine sensors, as well as the engine side of the uvch's. )?

Stupid question but where is the IDM, and its associated plug/connector?

Please elaborate on any electrical testing/diagnostics I can do to pinpoint this. I am thinking 1 of 3 things at this point:

1.) Bad injector - least likely (mostly because I don't want it to be the problem. I will fight tooth and nail to not pull it out, or go back under the valve covers again.)

2.) Bad IDM - maybe caused by the loose uvch connector on the passngr side? - not P1298 or 1316 codes though, so less likely.

3.) Problem in the harness ( short, etc..) - Expensive, but probably the "easiest" option to deal with. - this just feels like its the issue. The random "glitchy" nature of the problem seems to fit

 

To answer questions, but not to contradict - consider the following:

Hiccup or knock on decel - the red line is the ICP during a WOT run, and the moments following the run:



A situation like this is where logging really pays off, because it took the analysis of several PIDs during the event to sort out where things went wrong during those 10 seconds. With an array of disabled injectors, slapping them all in their collective butts with 3600 PSI just might contribute to a knock.

Millions of these trucks used to run fine with the stock fuel system, but those quick-disconnect O-rings have aged - and O-rings suck at sealing suction. Of the many people that have conducted the Hutch mod (including myself) most have commented on how their truck runs better and quieter. I have visually seen the air intrusion because I installed different variations of clear pre-pump fuel strainers. The bucking I had was completely deleted by tightening the injectors one time, and the Hutch mod at another time.

You mention the ICP/IPR looks good. I submit:

20% fluctuation in IPR at idle is not indicative of a sound seal on the injector O-rings - but I admit EOT can effect this. The last time I had a 20% jump in IPR at idle with a warm engine, I found a loose injector bolt. Tightening it up brought the number right back down where it belongs. I'm not professing you have a loose stick, but a bad injector O-ring would do the exact same thing. The fuel filter would blacken from filtering the oil out of the fuel after it has cycled through the return line, to the tank, and back in the bowl. The oil would be too diluted to discolor the fuel. This might be one of the clues you're looking for.

I'm not saying I have the answer, I suspect you may have a combination of woes, and it's confusing the situation. I have that tee shirt.

Electrical: You may find the UVCH link in my signature very useful here. As for the IDM/PCM bus connection, that does not travel through the engine valley. The IDM is lurking in the oh-so-convenient location of behind the driver-front wheel well, behind the splash guard - next to the PCM, but with a wall of steel between them.

 

As far as the IPR variation, the 12% was an approx recollection from over a week ago, and it would have been with everything "cold" less then a block from home,and prior to the new uvch's. The 10% reading was a definite number taken last night at fully warmed up, after a 30 mile drive. I'll double check cold and hot tonight.

Thanks for the tip on the pinout thread. Very good info, but would you happen to have info on the rest of the 42 pins? What/where do they go to? Oh, also, what does the EF stand for, in relation to the 1670 code.
So, I can test continuity at the engine side of the 42 pin, for each inj, and if I get approx. 3ohms, then everything is good between there and the inj., right?

So, what if I don't get 3 ohms? Higher resistance means what? (Short to GROUND?)
What about significantly less, or zero( open circuit/broken wire?)

So, if this test indicates a problem, I can further pinpoint it by doing the same test but at the external valve cover plug, to determine if the problem is in the engine harness, or under the valve cover, correct? (Obviously, with the new uvch, that would mean the inj. Solenoid most likely)

On the other end, specifically, in reference to inj.#5, I can test the male/body side of the 42pin, at pin 7(tan/black wire) to the IDM connector at pin 8, for continuity/resistance, correct? What resistance should I see there? Same or the power supply, passngr side, orange wire, 42pin #12 to IDM #24?
Am I understanding that right? What about any testing between the power supply/hv and the inj ground. Any kind of testing I can do there? I thought I saw something on Youtube about using a Powerprobe to test the circuit that way. Any thoughts there?

Do you know how to test the IDM itself, in a similar fashion, in terms of resistance/continuity on certain circuuts?

If I were going to go back in, does the failed cct on #5 make that the likely candidate for changing o-rings?

Given the high voltages involved, I'm guessing it would not be a good idea to grab the harness and do a wiggle test while its running?

What exactly do you think I should do, and in what order, as far as further diagnostics/repairs?

Thanks again for your help. I just joined, but I've been reading the forum for the 6-7 months I've had the truck, and I see you keep popping up on a lot of threads with helpful info. I was hoping you would respond when I first wrote the post.

 

42-pin connector: Your various engine sensors and controls pass through that - this is everything electrical that reaches the valley. I have wiring diagrams for the 2000 on paper, but everything else on the 42-pin won't cause a single cylinder to miss - the sensors and controls would effect the whole engine. If you really want to dive deep into this, you might want to seek out a wiring manual for the truck. I can post a specific section of the truck, but we can't wallpaper the thread with a whole manual.

The attached should be helpful enough.

After checking each injector pack for about 3 ohms, check each one in reference to ground and inspect the bottom wires for chafing. This will tell you the condition of the electrical system to/from the injectors and the 42-pin connector. I haven't yet verified your wire numbers/colors to the IDM, but if you got that from the references in the UVCH link - you're good. As for your readings - a poor connection will read infinite ohms, "OL" for Open Line, blink dashes, or whatever a no connection shows. A short (like touching the probes together) should read zero, or thereabouts - depending on the quality of the meter. Your description of the readings was inverted - an easy mistake when talking ohms but thinking voltage.

 

The IDM itself is one of the mysteries of the Ford universe to us peons. Swamps is the only entity I know of that completely reverse-engineered the IDM, and they sell an upgraded IDM - but they don't share the test points and diagrams.

 

I cleared the codes before going to work yesterday, and then checked again when I got home. The P1670 is gone, but it still fails CCT on Cyl#5. No other codes (Well, ok , the pretty much permanent 475/476 EBPV related stuff, and the overboost codes, since I played with the chip again.)

Thanks for the pdf link. Its helpful, but still missing a lot of info on the rest of the 42 pins. for instance, I was inspecting the wiring, coming off the male side of the 42-pin, and it looks like pin #23 may have had some chafing. The insulation is just about gone, but not quite showing copper. It is either light grey, or lt blue, with either a red or purple stripe. Any idea what this is?

As for the injectors wiring, I did the ohm check, at the female side of the 42-pin, and they all come back at 2.9-3.0 ohms, so that's good. What did you mean by checking each injector in reference to ground? How do I do that, and what do I look for? I get kind of confused with the electrical stuff.

How would I go about checking the integrity of the wiring between the male 42-pin and the IDM? I tried to do the same ohm check between the power supply line, and the corresponding injector wire, same as on the female side of the 42-pin, but I got nothing. Well, I guess it would "infinite" resistance? (meter displayed 1., same as probes in open air, not touching anything)

Oh, I forgot to mention in all of this, that the truck has always gotten really bad mileage. I only get around 15mpg. I assumed that fixing the leaky up-pipes and the turbo would help that, but it hasn't changed one bit. I don't know if that is a useful clue or not?

On the really bad news front, I think I see soot in the top of the degas bottle, either that or its just some sticky black gunk????? This is looking really bad..... I really can't afford new injectors (or the downtime to do it), and obviously it would be foolish to do cups and reinstall worn out old injectors. I'm also too far into this truck now to give up on it.

 

Reference each injector to ground: You know the pin for each injector, just check each of those pins with the red lead and the black lead on ground (clean engine contact).

Chafed wire: Gray with a red stripe is on pin 23. The book says that is circuit 318, and that pin is the + side of the Exhaust Pressure Regulator signal (EBPV control).

I see no IDM codes, so I'd leave the rest of the electrical tests be.

Soot in degas: I had that for two years before I understood what it was and did anything about it. I'm not saying don't worry about it, but I'll say I've seen worse - and the truck drives on. Tough bugger, eh?

That failed #5 CCT is aiming my attention at the #5 stick. A failed #8 and/or #3 is a common faux code - but #5 indicates an issue there.

To stay within budget, you can get a set of O-rings and check the hold-down bolt torque on all the sticks. When I say "check", I mean set the wrench to 50 inch/lbs and see if any of the bolts move. Every bolt that moves needs the stick pulled and new O-rings installed. Full torque should be 120 in/lbs on a warm engine.

I would pull number 5 injector. Look around in the hole for signs of water or exhaust intrusion. Inspect the O-rings and copper washer for any signs that would allow leaks in any direction. Check the solenoid plate gap for proper clearance. I've never had to do that last one, so further input will be needed. Replace the O-rings and copper washer.

Before re-installing the injector, you need to evacuate the fluids that drained into the cylinder when you popped the cup. There is a whole set of instructions for this phase.

 

When I check each injector to ground, what am I checking? What results should I expect to see, and what indicates a problem?

As I stated previously, when I had the valve covers off, I put a torque wrench on all the bolts. Every passenger side injector turned about 1/4 turn to reach 125 in/LBS. Every driver side one did not turn at all. Also, the glow plug on either cyl #3 or #5 (don't remember) was very loose. This was all with the engine cold, having sat overnight

So, are you saying this indicates that I should do o-rings on the entire passenger side (1,3,5,7)?
The thing is, at that point, my brain won't let me just do that. That level of pulling parts demands 8 new injectors, cups, and anything else I touch that might be worn out. Its just how I approach repairs, even if I know I can't afford it. I'll spend my last dollar to fix it right, and panic about it later, even though I know I shouldn't.

What you're saying all makes sense, but I swear it sounds more like its coming from the driver side, as far as the funky short/injector "slap"/knock noise. It sounds like injectors trying to "buzz", which leaves me thinking there is still something electrical happening too.

Any suggestions on where to find info on that solenoid plate thingy measuring? They do all sound pretty "quiet" when doing a buzz test. They buzz, but all but #7 sound soft and muted.

 

When checking for ground reaching an injector, you don't want an ohm reading - you want it dead-open. The way this works:

The injector solenoids always have power on one side. The signal that fires them is a ground to the pin on the solenoid connector. A short to ground here (chafed wire), can make the injector fire when it's not supposed to - bad juju. Wiggle the harness when testing for grounds to the injectors.

I suggest O-rings on #5 to verify this is the problem, or to discover if something else is going on in that hole. ICP/IPR ratios can also indicate a leaking injector O-ring. Tuners and faulty sensors confuse the math, so I typically ask for a spread of PIDs in a WOT log to compensate for creative tuning and bad hardware.

 

So, am I checking the power side of the injector, or the ground side, or both (one at a time)? Am I checking for resistance? (Ohm setting on meter.) Is the desired outcome the same reading I would get with the probes in open air (infinite?) Can I check this at the 42 pin (female/engine side), or do I need to pull the valve covers again and check at each individual injector?