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Discussion Starter · #1 ·
Hello everyone! I've been an avid lurker for many years now however I need some more specific insight...

2002 F250 XLT EC LB 7.3 4R100 4X4 176,000 miles
Stock its whole life

I live about 2.5 miles from work and drive home for lunch. Any day above 80 degrees ambient, my truck will slightly surge and intermittently stall along the path returning to work (usually coming up to, and stopping at, the same intersection). The surging happens both driving and at idle however the stalling only happens at idle such as coming to a stop light.

I've owned the truck a while now and I can remember replacing (in the last 2-3 years):

IPR;
ICP + Pigtail;
CPS;
HPOP (Ford reman).

Most recently (of course after the generic fuel filter/ oil change) I've:

dropped the tank and cleaned the screens;
rebuilt the fuel bowl;
installed RiffRaff FRx (stock pressure);
installed fuel pressure gauge (62-64 psi WOT or idle);
50 cent mod to under valve harnesses.

The troubleshooting so far in addition to throwing parts at the thing include having a local shop scan it and run buzz and cylinder contribution tests (90*+ day, engine up to temp). The thing tests perfect - no codes, sticks clatter evenly. I've used a couple different CPS types (blue and grey) - stalls with both. ICP connections are not oily and I haven't found any wiring that is chafing.

I thought I nailed it with a RFx a few weeks ago and figured I was running too high of fuel pressure however the ambient temp came up yesterday afternoon and the darn thing stalled out again - I didn't notice a fuel pressure drop/spike but I'm not sure I looked at the gauge in time. Each and every time the truck starts back up like nothing happened. Only have to shift into neutral and turn the key.

Other noteworthy symptoms include a noticeable tick, most distinctive than your typical clatter - sounds like a single cylinder. Truck doesn't ping unless I rap it out to 3200 rpm at operating temp on a hot day - when still warming up the thing takes the whole power band just fine. Power is typical for a stock unit and the injectors are original with original o-rings.

I'm looking to buy AE but I'm not sure which parameters to look for during diagnostics. Should I simply install an HPOP gauge to see if the pressure is dropping too low? This might be a stretch but can a flaky torque converter cause similar symptoms? Trans is original - maybe it locks up accidentally when the fluid is hot? I'm just spit ballin' now. Any input would be great...

By the way, if you've taken the time to read this far THANK YOU for the years of help. You guys rock!

Brian
 

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Discussion Starter · #2 ·
Ok, so I unplugged the fuel bowl heater for a week and experienced the truck dying several times. None-the-less, I left it unplugged for good measure - the thing is soaked in fuel from all my futzin' around...

After doing some more reading, I'm leaning toward a leaking o-ring so I picked up an Insight CTS and have some data for you guys:

Went for a drive...but didn't stall yet. Lowest recorded ICP is 458 psi at EOT of 144*F (not quite up to temp). I thought the injectors wouldn't fire below 500 psi? What is the lowest ICP to keep a running engine going?

Brian
 

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The PCM won't fire the injectors when cranking until 500 psi. After its running, it isn't unusual to hover in the 450-500 range at idle. Injector O-rings are a possibility. Do you ever hear a clicking when this happens - like the PCM resetting? Anything happen on the gauges or dash lights?
 

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Discussion Starter · #4 ·
I don't hear any distinct clicking during a stumble or stall. Once the engine is warm I can hear a different click aside from the clatter of the injectors but this noise is present all the time (well in the last some thousands miles).

The dash lights are pretty consistent with only the door ajar light on. I believe I've fried my VSM some years ago and never had it fixed - I just pulled my keyless entry module and use the key now. During a stall I never see any additional lights, no check engine light. I just pop the truck in neutral and it starts right up.

It did manage to stall on me tonight with the CTS hooked up. I'll have to pull the data log and see what it says.

Brian
 

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Discussion Starter · #5 ·
I've attached a quick chart of the ICP pressures and IPR duty cycles. There are three dips in ICP pressure, one of which stalled the truck. The other two felt like a hiccup.

I'm not too sure what to make of the IPR duty cycle staying flat during the first stumble - it looks like the pressure either didn't drop low enough or wasn't low long enough for the IPR to compensate. The stall event and second stumble both show an immediate IPR response. I was surprised to see the ICP as low as 232 psi without stalling...

Thoughts? Next steps? For some reason I'm having a hard time believing a bad injector o ring would be so intermittent.
 

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I'm watching how this works out. I have a similar problem and have gone down a similar repair path. Mine seems to stall at the 40 minute to 1 hour mark and will not restart for around 20 minutes with the hood up, longer with the hood down. All stalls come when reducing speed and lifting off pedal to idle. No codes on any of the stalls. Tests good on diagnostics.

Replaced the IPR a couple of days ago and made a 3 hour drive with no problems. Previously fixed HPOP leak, new injectors (not really to fix problem, just did it while it was in the shop and they cut me a deal), CPS, and pretty much any sensor, connector, or valve that is a common failure point. Went 500 miles with no issues, until a couple of days ago and it was back, so replaced IPR.

I noticed when replacing the IPR that a did have some diesel on the top of the motor. Ran the engine while watching for any leaks, but could not find any. Got it back in the shop but the inconsistency of failure and accurate diagnosis just seems to lead to throwing more parts at it.

I guess the good news is I'll have a "freshened" up motor, if I can ever figure out the problem. Getting stuck in traffic three hours from home is not a fun experience.
 

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It looks like the IC pressure drops first and then the IPR tries to intervene. So, what would cause a precipitous drop in IC pressure? You're right - an "intermittent o-ring" is unlikely the issue. It would have to be either a real drop in pressure or a falsely reported drop in pressure. A falsely reported drop would cause the IPR to kick in, but the actual pressure would spike which you would think would cause an increase in RPM, not a stall. Based on that logic, I would venture to guess this is a real drop in pressure. The only two possibilities I see are an oil starvation issue (i.e. the pump sucks air) or the IPR drops out. Remember, the IPR duty cycle is what is being commanded, not what is actually happening. If the solenoid "lost its grip" momentarily, I could see that causing the issue. You've changed the IPR itself, but have you checked its pigtail? Sucking air would be possible, but I think you should see other symptoms manifest - like hard starts, gauges flickering, dash lights coming on, etc.
 

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Discussion Starter · #8 ·
Thanks RT - good stuff! I like hearing options other than injector related :) :) :)

After a trip to bring things up to temp, the HPOP reservoir is less than an inch from the threads of the plug, but more interesting is the IPR pigtail... I never noticed it before but the back of the plug is filled with some kind of low viscosity putty (perhaps only low due to engine valley temperature). I'm going to clean it out and see what condition the wires are in - perhaps there is an intermittent short when this putty thins enough? I'll post up a photo again once it's cleaned out.

Brian
 

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Discussion Starter · #9 ·
So I really can't clean up the IPR pigtail very well for a clear inspection of the leads. I'm still wondering what the grey putty is that was used to insulate the wires and the closest thing I can find is Duct Seal. Now I can only find one brand that has a working temp as low as 210*F and this particular brand insulated 200 volts per mil - I'm skeptical of the IPR wiring being the issue but non-the-less I ordered a fresh pigtail from Riffraff (crazy good service by the way!)

Getting a little perturbed over the weekend I decided to change the oil just to check again if there was any contaminants - no fuel or water that I can find. Upon startup, the truck idles a wee bit smoother but nothing special. Truck experiences a few drops in pressure this week but surprisingly no stall event! The IPR was able to kick on in time and pressure rebounded. I attached a graph of the most interesting event which happened last night. The pressure dropped and then steadily increased until back to normal.

Since last night the truck has been running fantastic - idle tick is gone and power/MPG (seat o'pants/Edge Insight monitored) is up?

I think the conclusion here has everything to do with my change in commute without changing service interval. I used to travel 90 miles round trip for work and changed oil every 7,500 miles - worked just fine. About two years ago I moved closer in and now my commute is 7 miles round trip, but I never changed my service habits. I'd be willing to bet some junk got into the top side high pressure oil and/or IPR which what was causing the random hot stall.

Anyways long story longer, my plan is to keep monitoring and update if there is a smoking gun. For future reference I used the following TSB regarding OBS troubleshooting to gain some more understanding of just how important oil quality is on these systems. Pretty good stuff - thanks for the help RT :)

Technical Service Bulletin: 1994-1997 Ford 7.3 L Powerstroke - DIT Engine Information - Hot Shot's Secret®‎

Brian

Have to upload the chart later... Not working at the moment...
 

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Discussion Starter · #10 ·
Well I looked up the "putty" and it seems to be Duct Seal. Some brands are good to 200 volts per mm so I want to see how it holds up. None-the-less I ordered a new pigtail to have on standby.

Well I changed the oil again and wouldn't you know it? The injection cleaned up real nice...for about a week. It's funny how the tone and pitch of the injectors change with the quality of high pressure oil. It starts to get louder and "cackle'ier" a few minutes before it dies.

So I ordered another IPR and that did the trick. Smoothed everything right out. I left the original pigtail in there just to see if it indeed is the culprit occasionally.

I think I know what the root cause is... my service interval is based on the commute I used to have (90 miles a day). A couple years ago I moved closer to work and now I'm down to about 10 miles a day. I never adjusted the frequency of oil change to accommodate the lower per month mileage. Most likely I ran the oil too long and contaminated the IPR. If I ever get around to taking the old one apart and finding the culprit, I'll post.

Thanks for all the help!

Brian
 

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Discussion Starter · #11 ·
Ok, so that wasn't the trick....it was simply fresh oil in the rails or the IPR was bad in addition to the root cause or my mind playing tricks on me...

Died again come December after Christmas and I made it a weekend warrior until I finally found the time to pull the injectors. Check this out, stick number 3 - first one I pulled. Lower O-ring is in pieces :surprise:. I basically stopped there,because I was so excited to find the smoking gun I had to celebrate by running into the house, the injector in one oily hand and a beer in the other, coating every door handle to get to the wife to provide much needed proof I wasn't crazy! Needless to say, she wasn't too fond of the diesel/oil potpourri nor the "oil" bronze hardware.

Happily nailed the root cause - 177k on the ticker. Hopefully this helps someone. By the way, I waited way too long to pull the injector. Much easier than I thought. Thanks again to all the wisdom on here.

BTW, thinking of getting FF stage 1's and PHP tunes, just can't believe the price compared to stockers. And yes I know I could swap O-rings and be good for a few thou but....

Brian
 

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