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Discussion Starter #1
My truck has been running great for the last year or so with no issues. I just happen to be 14 hours away from home this week with my family and our camper. Yesterday when we were just driving the truck around town, I came to a stop and noticed that the idle seemed a little higher than it should be.... strange. Took off from the light, and as I was cruising down the road and let off the gas the motor started idling super rough....chug, chug, chug. I got back on th gas....th motor smoothed out.....and no other issues all the way back to the camp site.

Unfortunately I didn't have my monitor hooked up at the time, but I did hook it up as soon as I got back to the campsite. Everything looks fine....IPR volts, hpop pressures, ficm voltage etc, etc. I scanned the ECU for codes... nothing, everything showing good.

I've put a few more miles on the truck since the funky rough idle incident...and haven't had any problems, but with a 14 hour drive home coming up this weekend with the camper....I'm nervous as hell.

Could it have just been some random fluke? Anything else I need to check??

Thanks for the help!!
 

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I've always heard that an ICP sensor is usually the culprit for this sort of thing, and that it could be the sensor going out or could just be a bad connection to it. I'd at least check your connection for loose wires, oil in the connector, loose pins, etc. Other than that, I don't really have anything for you. Sorry.
 

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Discussion Starter #3
Thanks for the info. Yes, the that sensor was my first thought also. It's an OEM Ford sensor...and it's only a year old. I've put 20 miles on the truck since the funky idle thing....no issues as of yet. If it acts up again I guess I will see what my icp readings are. Thanks!
 

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Discussion Starter #4
Well, I'm 10 hours into my 14 hour drive pulling my camper. It did the weird chug chug idle thing to me as I was pulling out of the campground and stopped before getting on the road. The IRP rate (icp voltage) on my torque pro monitor setup was jumping around between 25 and 33%...usually it idles right at 22.8% once it's warmed up.

After that one time....it never acted up the rest of the day....all 10 hours of highway driving and getting off the interstate for fuel.

The ICP sensor is pretty new, and the plug is new with no oil on it (indicating a bad sensor). Could it be a problem with the IRP? Maybe it's sticking at the lower oil pressures?? I've had a bad ICP sensor before.....but when it went bad, it was bad....this is random.

ICP sensor? IPR? Could it be anything else??
 

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Discussion Starter #5
I've always heard that an ICP sensor is usually the culprit for this sort of thing, and that it could be the sensor going out or could just be a bad connection to it. I'd at least check your connection for loose wires, oil in the connector, loose pins, etc. Other than that, I don't really have anything for you. Sorry.
Are the ICP sensors more prone to give issues at idle, that an part and heavy throttle? The only time I had issues, was when off the gas...and rolling up to a stop light. The 14 hours drive home went fine...no issues at all. I haven't been able to duplicate the issue again....even after moving the wiring all around, and tapping on the sensor a little bit.

Everything seems fine now.....I don't like problems like that, it makes me nervous to drive the truck for any long distance not knowing if it could act up again.
 

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Could be an injector going, mine was doing the same thing and then #6 went, showed short in wiring but turned out to be failed coils.
It was a BWD injector swapped out awhile ago, at least it was under warranty, the new injector was a BWD but a Sure Power reman.
 

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Discussion Starter #7
Well....the truck has been running fine, until today. I was driving along, and let off the gas as I was coming over a hill on the way to to my house. I was going around 35mph....with the windows down so I could here the motor pretty well. All of a sudden when I had my foot off of the gas pedal, it was like I quickly tapped the throttle with my foot, just a quick little rev......all on it's own. Very odd........

At this point...should I just go a spend $125 on a new ICP sensor and swap it out? It's such a random issue, I have no way of really tracking it down, or troubleshooting it.
 

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Discussion Starter #8
**UPDATE**

Well, I put in a new ICP sensor just for the heck of it. It's been a few weeks, and several hundred miles....and more more random "funky idle for a couple of seconds" type issues.......until today.

So, same as before.....I'm on the highway driving along. I let off the gas as I get off at the exit and start slowing down. And the motor does that "chug,chug,chug" type idle for 2-3 seconds.......and then it goes away and idles smoothly. It happened to fast, I couldn't catch any of the readings on the HPOP, ICP, IPR off of my Torque PRO app. Scanned the truck again with both Torque pro and Forscan...nothing. All it good.

It's frustrating tracking down stuff like this. I wish it would happen all the time, or do it when I'm at home and can spend some time looking at all the PID's.....but it only goes it when I'm out on the road, and just for a couple of seconds . Very odd.
 

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My 96 is doing kinda this but it will die but restart. But doesn't die all the time just whenever I'm not watching the gauges
 

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Wish I had an answer! I mean I REALLY wish, because then I might be able to fix mine. lol I had a random lope quite some time ago. Thought I had fixed it. Came back the other day for about 20 minutes and is gone now, with no data to show WHY....everything looked normal. Only thing that was odd, but made sense since the RPMs were jumping a couple hundred RPM, was the ICP would rise a little bit when the engine revved. So yeah, these engines can be a real PITA at times. I've resigned to the fact that some things we just have to live with unless we want to bring it to a pro or spend ridiculous amounts of money chasing sparks. lol
 

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Discussion Starter #11
Wish I had an answer! I mean I REALLY wish, because then I might be able to fix mine. lol I had a random lope quite some time ago. Thought I had fixed it. Came back the other day for about 20 minutes and is gone now, with no data to show WHY....everything looked normal. Only thing that was odd, but made sense since the RPMs were jumping a couple hundred RPM, was the ICP would rise a little bit when the engine revved. So yeah, these engines can be a real PITA at times. I've resigned to the fact that some things we just have to live with unless we want to bring it to a pro or spend ridiculous amounts of money chasing sparks. lol
Yeah, I think at this point I'm just going to keep driving the truck.....and hopefully the problem will just go away, or it will get bad and consistent enough so that I can troubleshoot it.
 

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Discussion Starter #12
**UPDATE**

Well, the problem happened again today on the way home from work. And it did for a pretty long period of time, so I was able to get some numbers on the PID's and more info.

So as I was driving around 55mph, the truck felt like someone had just quickly pressed the gas pedal for a spit second...just a quick jerk. It did it a few more times after that. The Throttle Position PID reading stayed steady when this happened, right around 20%. So the ECU wasn't sensing that I was calling for more throttle.

Then after a few miles, I let off the gas to make a turn....and I noticed that as I let off the gas the injectors sounded a little funny, and the truck wanted to idle fast. It held the idle at around 920rpms (usually it's around 650), my IPR rate was at 34.0% (usually it's at 22.8 during idle), and my HPOP pressure was 640psi (usually it's around 580 at idle). FICM voltage was 49.0, and battery voltage was around 14.2v. Even after getting on the gas several times, every time I let off.....it would fast idle. But, the idle was smooth...not rough an erratic. Just a higher than normal idle. Could the IPR be sticking? Not sure why that would explain the weird injector sound though while I was off the gas and coasting.

I drove for a mile or so, and the truck just felt weird. Every time I would let off the gas and coast the injectors would sound weird (like every other one was off or something), and it would idle fast. When I would get on the gas, everything would sound normal......but it just felt odd.

Jut as I pulled in the driveway thinking I could finally do some troubleshooting......I feel the idle drop back down to normal, and everything is fine. I couldn't get it to duplicate it no matter what I tried. Like before, I scanned the ECU...no error codes.

With this new info, any ideas???

Thanks so much for the help guys!!
 

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Well, the IPR numbers are what the computer is commanding, not what it is actually doing. So, the computer commanded a 34% duty cycle vs the 22.8% you expected. As for why.....ya got me! lol
 

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Discussion Starter #14
So it's not a ficm issue.....it's a ECU issue? Why would the ECU command a higher than normal IPR rate if there was no input from the throttle?

This truck is driving me nuts.....
 

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The variables are many. The computer uses dozens of factors to determine what to command the IPR to do. It's got to take into account the outside temp, temp in the intake, the flow of air, current boost level, and on and on before it can determine what the IPR should do. I would imagine a sensor wire being a little loose or even a little dirty might have an impact. Short of an all-out war against your wiring harness, and a mass replacement of all sensors, I don't think you're going to find the culprit soon. However, at least take the time to check the easy ones to make sure you don't have gunk in em, or a loose connection.
 

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IQ,

You made the following observation "The Throttle Position PID reading stayed steady when this happened, right around 20%. So the ECU wasn't sensing that I was calling for more throttle". Were you maintaining a steady position on the gas pedal? Is the TPS sensor on the gas pedal acting erratically? I believe the TPS in the pedal is just a simple potentiometer. I know with old audio equipment that the volume potentiometers can dry out and cause the sound to crackle or drop out all together.

Cj
 

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Discussion Starter #17
Yes, I was maintaining steady pressure on the pedal, the PID for throttle position was showing a steady 20%......but the truck was surging a little bit with the ICP and IPR PIDs jumping around........

If the throttle PID was jumping around while my foot was steady on the pedal....then yes, I would say you were right and the potentiometer in the pedal was bad......but it wasn't doing that.

The strangest part is that when I let off the pedal, for some reason the ECU (computer) was commanding a higher IPR rate (33 vs a standard idle IPR of 22) and making the truck idle faster than it should.

Like others have said.....at this point, I'm leaning towards a wiring/harness/connector issue. I would say that it might be a bad IPR.....but if that was the case, it wouldn't make sense why the ECU would command more IPR to make the idle higher.

With so many sensors, harnesses, connectors on these trucks......it could be damn near anything. I know it sounds odd ...but at this point, I'm just hoping it's going to get worse and more consistent so I can actually make it home in order to start testing stuff.
 

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And don't forget that the pedal is actually a triple redundant system, with a failure making the pedal go dead. Any anomalous readings are supposed to be corrected by using best 2 of 3, or something like that....I really can't remember the exacts right now, but something like that. lol And yeah, I get the desire to wish it would just get worse. You know, another thing that worked for me once when it was surging a LOT no matter what I did was a hard reset....like disconnect batteries for 20 minutes reset. Sometimes that good ol' ON/OFF sequence helps!
 

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Discussion Starter #19
I saw that with Forscan I can reset the PCM and delete all of the adaptations. I haven't done it because I wasn't sure if it was a good idea.....but at this point, I'm not sure what it would hurt.

I had the problem on the way back from work today. Came to a stop, noticed the high idle, hpop at 950-ish, IPR rate at 28%......started driving again, let it idle... everything back to normal.

What the hell....just crap out all ready!!
 

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Discussion Starter #20
Well...it did it again this morning. Driving down the road, let off the gas...and the motor revved up on it's own like I mashed the gas for a split second. It sure does act like an ICP sensor issue.

I wonder if there could be an issues with the pigtail or connector?? If I completely disconnect the ICP connector, it throws a code.........would a quick bad connection throw a code? That's the strangest part.......even after this thing does the high idle for a minute or two, and rough idle...and the "auto-rev" like this morning....no codes.

Maybe I will go back to the stock tune........I'm pretty sure that some of the "custom" tunes out there will suppress some of the codes the ECU tries to throw. Back when my turbo was sticking.....I would get a low boost code when running the stock tune, but no codes when running my IDP tunes.

I think I might go back to the stock tune....see if I get any codes that might help me out?
 
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