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Discussion Starter #1
I was taking my son on a road trip to see the Union Pacific Big Boy train a couple of weeks back and the check engine light came on for a second or 2 and the truck went to limp mode for that duration. It hasn't come on again since. I pulled over, checked the oil, coolant, etc, and all was in order. Temp was good, etc. I have a power steering pump that has bad bearings (loud) but I can't imagine that being the culprit. I checked for codes when we returned home and there was nothing. Is this par for the course or should I be looking somewhere for something?
 

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What did you use to try and pull the codes?

99% of the code readers out there will not read Fords codes on these trucks.
 

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Discussion Starter #3
What did you use to try and pull the codes?

99% of the code readers out there will not read Fords codes on these trucks.
Hi Bugman, I used the Superchips programmer
 

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You might need to do some checking on the Superchips programmer and see just what codes it will pull and what it won't.

If there was a CEL there should be a stored code.
 

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sounds similar to the issue that i had a month or so ago. My buddy used his high dollar Snap on to read the stored code (It was in memory but not active since the light was not on). Mine was PO221 Switch B Performance. (Throttle pedal) He cleared the memory and I have not had the issue since. No guarantees it will not come back tomorrow but so far so good. I am using this truck for light local duty at the moment because of this issue. I would be courious to see what your code is. My suggestion is find a friend with a real good scanner. A cold six pack around quitting time always works for some good scan time.
 

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Generally I agree that if the CEL comes on there should be a code stored in the PCM. There are faults on a 7.3L that can flash the CEL intermittently. The first that comes to mind is a "PCM Reset" where the power or ground to the PCM is momentarily interrupted. This could include a chaffed wire or any of the PCM outputs that pull voltage down on the ignition feed to the PCM relay or the VPWR circuits. This type of a fault is usually momentary and more likely to happen on acceleration if it's harness related. When this happens the PCM momentarily shuts off then reboots and the CEL comes on due to the normal bulb check. The second is intermittent sensor faults that occur too fast and too intermittently to set a code. Generally with Ford's, a fault has to occur for 6 seconds or longer to become a pending code and once the fault is seen three times within a time frame it sets a code and turns on the CEL depending on the code.

I recently had a 2002 Excursion 7.3L which was mis-diagnosed 2X before landing in my bay that was doing this. It took a little time and some observation to verify the concern and I was fortunate to be able to identify the accelerator peddle position sensor had an intermittent drop in one of the sensors with a data recording. I thought it was strange that I could clearly see the CEL come on for a second but the PCM did not think it was an issue but rather reacted to the skewed sensor input and erroneously set an ICP code. It made sense once I saw the data recording and it goes to show how intermittent problems can appear to be something they are not.

Isn't this fun?


Sorry for the rambling post. ;)
 

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Discussion Starter #9
Generally I agree that if the CEL comes on there should be a code stored in the PCM. There are faults on a 7.3L that can flash the CEL intermittently. The first that comes to mind is a "PCM Reset" where the power or ground to the PCM is momentarily interrupted. This could include a chaffed wire or any of the PCM outputs that pull voltage down on the ignition feed to the PCM relay or the VPWR circuits. This type of a fault is usually momentary and more likely to happen on acceleration if it's harness related. When this happens the PCM momentarily shuts off then reboots and the CEL comes on due to the normal bulb check. The second is intermittent sensor faults that occur too fast and too intermittently to set a code. Generally with Ford's, a fault has to occur for 6 seconds or longer to become a pending code and once the fault is seen three times within a time frame it sets a code and turns on the CEL depending on the code.

I recently had a 2002 Excursion 7.3L which was mis-diagnosed 2X before landing in my bay that was doing this. It took a little time and some observation to verify the concern and I was fortunate to be able to identify the accelerator peddle position sensor had an intermittent drop in one of the sensors with a data recording. I thought it was strange that I could clearly see the CEL come on for a second but the PCM did not think it was an issue but rather reacted to the skewed sensor input and erroneously set an ICP code. It made sense once I saw the data recording and it goes to show how intermittent problems can appear to be something they are not.

Isn't this fun?
Mine was upon acceleration for sure. Thanks for the great info there! Would it be worthwhile to go to an auto parts store where they do a free scan for codes, or would their scanners not be likely to retrieve the code?
 

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Were you running with a Superchip Tune?

Just curious as I have one of those and it would flash the CEL on rapid acceleration (which is what you described?).
 

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You might disconnect your battery to the vehicle for about 10 minutes or so.then reconnect just to clear your PCM. You might have to reset your radio and clock.
 

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DO NOT erase anything until you find out what it was that caused it in the first place. Yes it could be completely random and mean nothing or it could be something ready to happen. Mine was a throttle pedal code got it erased and it has not came back on in several hundred miles. If it comes back I will know where to start. Like I said find a friend with a shop and A high dollar scanner. Even if you have to pay a buck or two you will have a baseline. I do not think the box auto parts stores will be of any help, at least they are not by me. Please let us know what you find.
 

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Discussion Starter #13
Were you running with a Superchip Tune?

Just curious as I have one of those and it would flash the CEL on rapid acceleration (which is what you described?).
Yes, it has a superchip and it was in performance mode. I was going fast (for this truck) and in order to overtake a slower vehicle in front of us, I had to accelerate even further. The truck was close to full throttle when it happened.
 

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ARTICDRIVER. I do not think that your truck momentarily losses power wile at hard acceleration wile flashing the CEL does it? No one would install a Performance program that causes lack of performance. I thick the whole question is the loss of power under load with a CEL flash. Still say take it to a good scanner.
 

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In response to above.
My opinion is the Superchip Performance mode caused this issue.
I only used Superchip performance mode for 2-3 days and as soon as it flashed CEL once, I never used it again. Instead I use the milder mode and have never had a CEL issue again. My opinion Is that its an early tuner and there are much better ones on the market today. My fear was that the tune might actually be so poorly written that it could result in damage when it generated the CEL.
I don’t recall what effect it had on the accelerator the single time it occurred.
As for installing a Performance Programmer that loses performance...it improves performance all the way up to the point it loses performance and its an old tuner about 18 years old now. Many improvements have been made on tunes in the last 18 years.
 

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ArticDriver, I agree with you that the tuner could cause the light flash. Also that the older tuners may not be fully able to deal with all situations while driving. You stated that you do not recall if you had the lose of power issue. My whole point is if any vehicle I own gas or diesel car or truck ever gives me a CEL and a performance glitch even for a second or two I want to know what it is. Most of the time I have easily been able to find the root of the problem with a simple scan with my Actron. However with our trucks I have to go to a garage with the proper reader. This was the case with my truck a month ago. Without the scan I would have been chasing my tail. I do not have any experience with the Superchips program is it capable of reading ALL the codes stored in memory or just some of the main ones?
 

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Discussion Starter #17
I put that programmer in there 14 years ago, almost as soon as I bought the truck. It's always on performance mode, other than when I am towing the very occasional trailer. It's never been an issue. I'm fine to go back to stock settings as opposed to performance mode and lose the 110 hp gain ;) ;) ;) or maybe like 15 hp gain in reality...
 

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If you have not had the problem in 14 years in performance mode, and you just had one I would think your problem may have been something besides the chip. Your original post is almost the same as my post about the loss of power and CEL flash. Difference is yours is a 95 with a chip and exhaust and mine is a 97 bone stock.
 

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I put that programmer in there 14 years ago, almost as soon as I bought the truck. It's always on performance mode, other than when I am towing the very occasional trailer. It's never been an issue. I'm fine to go back to stock settings as opposed to performance mode and lose the 110 hp gain <img src="http://www.thedieselstop.com/forums/images/smilies/wink.gif" border="0" alt="" title="Wink" class="inlineimg" /> <img src="http://www.thedieselstop.com/forums/images/smilies/wink.gif" border="0" alt="" title="Wink" class="inlineimg" /> <img src="http://www.thedieselstop.com/forums/images/smilies/wink.gif" border="0" alt="" title="Wink" class="inlineimg" /> or maybe like 15 hp gain in reality...
Maybe we don’t have the same Superchips. Mine has Performance and also a mild tune option.

I guess if you get on the throttle often and have never had this occur in 14 years then I jumped to conclusions.

By all means see what codes are stored and try and see if you can get it to occur again. Maybe it was a one off.
 

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Discussion Starter #20
I stopped at an Advance Auto and had them try to read codes, and again, nothing showed up. The truck is running fine. I guess I'll wait to see if it happens again. If so, I'll bring it to a diesel repair shop and let them have a crack at decoding it.
 
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