Hey folks, thanks for taking the time to read. I have a late 97 f250, California truck with splitshots and an MME03 PCM--all stock gear. Only upgrades I have is a DP, straight pipe, and DIY Tymar. I took my chip out to eliminate that as a cause. So I am having this INTERMITTENT issue, which after reading extensively through the forums, I thought was either the bad CPS or APP/IVS. So I replaced both of those and am still having the problem--so those have been ruled out. I am also not getting any codes or CES light, and the truck passed the NGS buzz test and cylinder contribution tests.

What's happening:

the following symptoms happen when it is cold or hot outside, engine is cold or hot, hasn't been run in weeks or was just run 10 minutes ago. After several test drive cycles, I can't nail down anything associated that would cause the problem--and remember, these issues all happen at the same time when they do happen, but the poor performance is intermittent.

1)rough idle--The truck idles as if maybe one cylinder misses intermittently. No codes, no idea why, doesn't happen all the time. Sometimes it will idle rough right from start, sometimes it takes a while driving around and the idle gets progressively worse until when it "misses", it shakes the truck.

2)while driving, for a split second, the truck will fall on its face as if the engine shut off. Similar to the "bucking" that people describe with a bad Accelerator pedal assembly, so I replaced that with a brand new factory piece, still happening.

3)occasionally, more rarely than the other issues, the truck will have a complete loss of power under acceleration. I'll be going down the road, running ok, and when I put my foot in it, nothing really happens. Even when I put the pedal to the floor, the truck will speed up really slowly and do the missing/bucking thing described above. Also, not blowing smoke when I put my foot in it, so I'm 98% sure whatever this is, is a fuel issue.

What I've done:

I haven't spend the coin on AE, but what I do have is Torque with a bluetooth OBD adapter. So I hooked that up and live scanned HPOPressure, IPR duty cycle, EBP, Boost, engine oil temp (to make sure I was operating the truck at temp), and then compared that to throttle input and RPM. When the truck is running normally, everything looks fine. When this intermittent issue is happening, everything looks to be operating as it should in reference to one another, but when I input over 90% throttle, it's as if I barely stepped on the pedal at all. All of the aforementioned sensors read properly in reference to one another, even when the "missing" thing happens.

I have also pulled the PCM and looked very carefully over the entire board for burn marks or bubbled resistors/capacitors and what-not, all looks well, just like it's brand new.

What I'm thinking:

If it were an injector issue, it wouldn't be intermittent. If it were a bad PCM, the truck wouldn't run. If it were a bad IDM, I don't think it would be intermittent, right?

Could an intermittent issue like this be a bad ICP or IPR?

Final question, largely unrelated, but hopefully someone will know. When operating at idle, the Torque App scanner sees proper 450-500 PSI in the HPOP system. When running at or near WOT, I max out about 25-2600 psi. Considering this is a split-shot injected truck, is that unreasonably low? I know the splits use more oil, which would explain not running in excess of 3k psi. But I also think it's a stock HPOP (far as I know), and I've never heard of a properly running HPOP operating under 2600 psi at WOT--but nobody really talks about what these things do with the split shot injectors... So any input you guys have would be greatly appreciated. I'm newly freed from all of my obligations in life, so I will have time to test and poke and prod for whatever yall come up with. My brain is racked, and so is my friendly neighborhood Ford heavyline lead tech. Thanks everyone, I look forward to your help.

 

Hi Brian, It sound to me that you have a come and go electrical problem, but I'm no expert by a long ways. A couple of questions, first where did the CPS come from. It is recommended to use a Ford or IH CPS only, as the parts house ones don't seem to work on these trucks. Secondly, have you checked the valve cover gasket and it's harnesses, both engine side and under valve cover for burned pins/melted connectors? Have the pigtails to the valve cover gasket ever been replaced, and if so were they soldered in place or were but connecters used? I had a come and go miss on the 97, until it came up with a dead bank. Some time ago I had a melted connector on the engine side, and I was in a hurry and used butt connectors to connect the wires. Long story short the connectors corroded, and caused the shut down of that bank. I removed the connectors and soldered the wires, and all is good. It has been reported that the main wiring harness to the engine can fatigue and short out where it drapes over the drivers side valve cover. A removal of the loom and a close check of the wires might be in order. Just a couple of places to check and a bump to the top until some of the other guys check in.

 

Thanks for your input farmert . The CPS I bought from Ford directly, it's a gray one, I have three of them now, same problem with any one of them installed. I am relatively certain that it's an electrical issue too. The motor has 176k on it, and all the stock parts are now 18 years old... So it's not beyond the scope of reason that fatigue might just be the factor here. What I am thinking is, if nobody can give me a relatively definite cause based on hearing past experience from others, like say some intermittent issue with injectors or something, then I might just to a top end overhaul of all the electronics; glow plugs, UVCHs, valve cover gaskets, inspect all the cable ends and replace as necessary, IPR, ICP, EBP and tube cleaning, etc... If I can stay away from injectors, then I should be able to do all the other stuff for under a grand and have the piece of mind of having all new goodies under there. But I'm only going to do that if nobody has some definitive answer as to what it might be... I don't want to go through all those parts and labor only to find out I had a bad IDM or something and nothing that I replaced needed it.

I'm going to get out there today and poke around the wiring connections, check the ICP socket for oil, and have a look-see. I haven't found anything thus far that might be the culprit, but maybe it's hiding!!

 

I would check the uvch's for burnt pins, the tin nut on the back of the ipr, and oil in the icp. Another thing just for piece of mind woul be fuel pressure.

 

My dad's truck had a similar issue. When he brought it to me I started digging around and I found the valve cover gasket on the drivers side had some burnt pins. I replaced the gasket and replaced the wiring to it and all is well. I am not the best solder guy so I used some pass through crimp connectors and used heat shrink to help prevent corrosion. I would check them closely.

 

I'd pop the IDM off and shake it, listening for water. It might have shorted out inside.

 

The very first thing, and simplest thing I would do is, check the oil. Just had a case with the same symptoms, and the engine was over 2 gallon low on oil. Turns out one of the injector o-rings went bad and in the course of 3000 miles it used that much oil. If the oil level is good, then I would look at the UVCHs and gaskets next. If you do replace those, go with the Motorcraft '99-'03 Super Duty ones from Riffraff. They are an upgrade, and cheaper!

 

Good advice, Bill. It's always best to check the cheap and easy stuff first.

 

I had almost the same problem with my truck. I assumed it was the CPS, but that didnt fix it, and then one day it just died and wouldnt restart. I didnt have a fuel pressure tester so I could not test for that, but did make sure it was flowing by cracking the banjo.

To make a long story short after I looked at everything I could from my end I had to assume the IDM was bad. I took it to a shop just to verify, and I found out three issues with my truck.

My fuel pump was weak (Mech said he didnt know how on the earth it was running before with such weak pressure)

The IDM as I assumed was bad.

My diode shorted out. We think the IDM finally completely went out, and caused a power surge enough to fry the diode.

 

hey guys, thanks for the attention. So I did some rooting around and think that I may have found a culprit. The valve cover wiring harness connector on the driver side looks to be oily. I can't find any other source for the oil, so I think I may have a gasket failure there that's causing this intermittent issue. I would think that would case a fault code of some sort, maybe a injector or glow plug bank fault or misfire detection or something... I don't know. But I also just picked up the AE SP-03 Ford bundle last week so I'll be plugging in and tinkering with that this week too.

What it looks like for now is valve cover gaskets and harness pigtails, and UVHCs, glowplugs, and injector o-rings while I'm in the valve covers (as there are 176k miles on all that stuff), and an ICP and possible IPR. It's a couple hundred bucks worth of parts, but it's also piece of mind and a good time to replace all that stuff anyway with that many miles on them all.

Any guidance on glow plug brand pros and cons? Bosch, Wellman, Motorcraft, Platinum Performance... Valve cover gasket brands?

Finally, with the HPOP/ICP issue I talked about above... I shot an email off to Joey over at Terminator. I am topping out at about 2550psi at WOT. While that sounds low to me, I am also nearly positive I have split shot injectors, which use way more oil out of this stock 15* pump. Does anybody know if that's normal for a split shot truck, or should I look at replacing the HPOP with a new IPR while I'm on this maintenance kick...? This is looking more and more expensive. At least the injectors are passing buzz and contribution tests for the time being so I don't need to replace those. Thanks a bunch fellas!

 

Motorcraft or International on the valve cover gasket, and Motorcraft/Beru on the glow plugs, if you want to do the job only once. Clay at Riff Raff Diesel can fix you up. 1994-1997 'OBS' 7.3L Powerstroke

 

I know all to well how the expenses pile up but with that many miles I would have Rosewood go thru the injectors. It will act like a new truck if you did.

 

I personally think you are going a bit overboard with replacing the sensors but I do understand that peace of mind.

Since the IPR and ICP can be replaced independently of the components under the covers I’d hold on them. To be honest every time I have had issues similar to what you are describing it has been the UVCH being toasted. I rarely see the VCs cause the bucking, but more so GP failure. Regarding parts go with OEM components from RiffRaff… best prices on the net! And usually better than the crap doorman prices from your local parts from china/mexico in a box. NEVER USE AUTOLITE GLOW PLUGS....THEY SHOULD BE DISCONTINUED!!!!

Here are links for the components under the valve covers

1. VC Gaskets x 2 Valve Cover Gasket 94.5-97 - Riffraff Diesel Performance
2. UVCH X 4 Under Valve Cover Harness 94.5-97 - Riffraff Diesel Performance
3. Rarely ever are reusable - DOG HOUSE ORINGS CCV Vent Cover Orings - Riffraff Diesel Performance
4. ZD-11 glowplugs x 8 Motorcraft Glowplugs ZD-11 - Riffraff Diesel Performance
5. Alliant Injector Orings Alliant Injector O-rings - Riffraff Diesel Performance
6. If you want POM a new GPR Glow Plug Relay / GPR - Riffraff Diesel Performance

That all being said you can always upgrade to a stancore relay which will provide significantly more amperage to the glow plugs, but I have seen them eat pins on the VCG before too. I have had one for a few years and love it.

Considering all these parts are about as much as a new ICP and new IPR. I personally have never had to replace an IPR, I have had to rebuild them, but never have seen a failed sensor. I have heard of them going bad though, its just not as common as people make it out to be in my experience. The rebuild kit with orings, new nut, and split ring are a few bucks vs near 200$ for a new sensor. I'd do that prior to buying a sensor/

Make sure your tin nut is tight too. This can cause issues, but to be honest I have had mine fall off for thousands of miles and the truck didn't run one bit different IMO(Sure to catch hell for that statement)

RiffRaffs Alliant injectors Orings are as good as you can get, they are factory original equipment and the same stuff you will get from the FORD dealership.... for 4x the cost.

 

Um, it's not exactly "overboard with the sensors"; the only sensor mentioned is the ICP. But indeed, it can be tested, for a lot less than the cost of replacing it, esp. now that the OP has AutoEnginuity.

 

I guess I missed the obtaining AE part...test them for sure. I was just the opposition of throwing parts at it not knowing if they were bad. That was all