Intermittent accelerator problem

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Mar 6, 2015 | 07:03 AM

yert37388

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Intermittent accelerator problem

Hello all, newbie here. I have lurked and learned lots from this and other forums in the past but I seem to have a gremlin that I'm hoping someone can help with. I really appreciate any advice/guidance you folks may offer.
Thanks, Trey in TN

2002 Ford F350 Powerstroke, 7.3L, Automatic, 4 wheel drive
AFE Stage II Intake, 5" full exhaust, TS 6-position tuner chip, Swamps 140lb injectors

Intermittent accelerator problem: no response, just goes to idle. Runs perfectly with no other issues but zero response when the accelerator it pressed. There seems to be no pattern to the problem as this happens at any speed/position on the pedal. When the accelerator goes out the check engine light in the lower left corner comes on. All fuses are good.
Symptoms began a month or so ago feeling like an occasional 'hiccup' or hesitation. Symptoms occurred a few more times until a couple of weeks ago (Friday, 2/20/15) when it left my son stranded a few miles from home. He was able to limp it to a parking lot and we left it over night and went and towed it back to the house the next morning. The truck started and ran fine just no accelerator so we towed it idling so we would have power steering/brakes, etc. As we neared the house the engine light went out and the accelerator began working and he was able to drive the truck the remaining 1/2 mile home.

Most all of the research I did came back with the Throttle Position Sensor as the culprit. I was able to order one (the complete accelerator pedal assembly that is*) at a Napa store in a nearby town and picked it up on Tuesday (2/24). As soon as I installed it everything worked fine.

As an aside, I have read a lot about the mid-2001 switch from the units with the TPS (Throttle Position Sensor) and IVS (Idle Validation Switch) as separately connected units to the 'new' style where these parts are combined into one and there is a single 5-wire connector. Being a 2002 there was no question as to which one I had. Just be aware of the difference. Also, this part is simple to change. The connector has a clip that you pinch down on with your thumb and then pull off. I use my little electric impact with 1/4" extension and a 10mm socket. Zip, zip, zip an you're done. It takes me longer to get my tools out.

A few days later on Friday (2/27) it presented the sporadic accelerator symptom a couple of times again but was able to get the truck home. The next morning I unplugged, cleaned (CRC Contact Cleaner), and dabbed into the connector a small amount of dielectric grease to insure good connection. (I had read that in my research as well). That seemed to work beautifully and he said it ran fine all day and until the next afternoon (Sunday, 3/1) when it began acting up yet again.

I continued to research and could find nothing that would suggest anything other than the Throttle Position Sensor. I read that some other folks had gone through a few of the Napa/aftermarket units though so I began thinking that maybe I had just gotten a bad unit.

On Tuesday morning (3/3) I called the Napa store and explained my problem and asked if he thought I may have gotten a defective unit. They guy said he didn't know much about it but he'd would let me talk to the manager. After being on hold for a few minutes the same guy came back and said they would have a replacement the next morning. So, I guess their willingness to replace a $100 electrical part without discussion confirms that this apparently is 'a thing'.

Before I left Wednesday morning ( 3/4) I went out and removed the Napa unit from the truck for the exchange and since it's a simple plug in reattached the old one. The old one seemed to work fine when I started it but that's been the way of it - good then bad with no real rhyme or reason. Anyway, onward.

I picked up the unit and installed it as soon as I got home. It seemed to work fine although this unit felt like it didn't respond until the pedal was pressed further than the others (maybe 1/8 of travel). But it was installed so, thinking positive, I had my son come by and pick the truck up to drive. He was gone all of 15 minutes when he called me saying that it had done it again but he had been able to get it into a parking lot to park it. I went and picked him up and we left the truck to cool off (it and me as well).

Thinking that maybe our problem is effected by heat/running-time I decided to wait a few hours and then go try to get it back to the house. We headed to get it after 3 hours. On the way I also explained that I had read about the cruise being a separate signal to the PCM and that if the accelerator quit working that the cruise should still work (if in fact the pedal was our problem).

The truck acted fine when started and we headed home (about 4 miles away) with him in the lead. About half way home he called me saying that the accelerator pedal had quit working again but he had the cruise set at 30 and it was still going (one more strike against the pedal assembly). About half a mile from the house there is a curve and a hill that he had to slow for and dropped the speed below 26mph which apparently shuts off the cruise from being able to resume. We were able to back it into a pulloff on the side of the road and left it for the night. Waking up to snow and ice the next morning we went around 11AM and were able to drive it the rest of the way home with no trouble.

I have about reached the end of my rope on this. I feel like the pedal is the problem but I don't know that I can go back to the parts store and claim two in a row without some evidence.

To recap:
1. I have replaced the accelerator pedal assembly - twice (with Napa part 825-5015 which I am given to understand is possibly a reboxed Dorman part) (I have since learned that Autozone can order the Dorman part 699-203 as well)
2. I have determined that the truck will still run cruise control even after the pedal assembly quits functioning which further points to the pedal assembly as the problem
3. There are no blown fuses
4. I inspected the wiring harness to/from that unit and found no issues
5. Based on how it is acting i still feel like the problem is the TPS. I wonder if I should buy a Ford OEM pedal assembly in hopes that my problem lies with the aftermarket parts
6. I have not retrieved any codes - I have learned that my standard OBDII reader won't pick up the 'soft' codes although I understand that the problem has to be happening at the time for those to appear?
7. I cannot find any faults with the wiring/connector. I can only think to take it to a dealer to attempt to retrieve a code however I have seen numerous posts telling how dealers often seem to point to the chip as the potential problem and refuse to look further until that has been removed.

Given this detailed (albeit lengthy - sorry) history would anyone have any suggestions for my next move?
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Mar 6, 2015 | 09:25 AM

DieselDan10191202

New User

Joined: Mar 2015

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From: missouri

2004 6.0 5" diamond eye, sinister egr/coolant filteration kit, blue spring update kit,

ive had this problem before and pulled the accelerator pedal assemblie out completely and put pb blaster on the pedal position board and it fixed my problem. it is dirt and dust that gets caked on the board. Try cleaning it.

Mar 6, 2015 | 09:40 AM

kwilson1

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Joined: Jan 2013

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I had the EXACT same issue and also tried the NAPA pedal/sensor, twice. Then went and bought one from Ford and problem solved. Napa did refund my money.

Mar 6, 2015 | 10:26 AM

acf6

Post Fiend

Joined: Aug 2010

Posts: 13,710

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From: Manchester, CT

I would start with returning the napa one and go to Ford. I've never had any good luck with napa parts, especially electrical

Mar 6, 2015 | 12:35 PM

SDElwood

Beer Fridge Finder

Joined: Apr 2003

Posts: 14,988

Likes: 1,151

From: Savannah, GA

Yep - been there done that... cleaning it will work most times. If not, only get a Ford replacement potentiometer... I guess the Chinese haven't got them figured out yet.

Mar 6, 2015 | 04:17 PM

yert37388

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Thanks for the feedback. I ordered one today and my dealership says it should arrive tomorrow. Hopefully I will have a success story to post.

I appreciate your help! : )

Mar 6, 2015 | 07:17 PM

DieselDan10191202

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Joined: Mar 2015

Posts: 18

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From: missouri

Quote:

Originally Posted by SDElwood

Yep - been there done that... cleaning it will work most times. If not, only get a Ford replacement potentiometer... I guess the Chinese haven't got them figured out yet.

Ive had the most problems out of my 97 but im poor so i cleaned it 2 or 3 times and then just bought a ford replacement lol.

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Mar 13, 2015 | 05:57 PM

yert37388

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Well after a lot of back and forth we're back on the road.

Tuesday morning I picked up and installed the pedal assembly I got from Ford returned the one from Napa as defective. The truck ran great that day but left my son stranded again that evening when he went to a meeting in a nearby town 20 min. away.

At that point I had done all I was prepared for. We were able to go back over that night and get it. It seems that after sitting for a few hours it will act right.

Anyway we got 10 min. down the road and he lost accelerator again. Fortunately he had set the cruise so we were able to motor on back. Also fortunately the Ford dealership is on our way into town and we were able to idle it off the road and into their service dept. parking lot.

I called into service the next morning and gave them the history and they brought it in and started searching for the problem. After a while the tech was able to find a partial break in a wire in the engine bay. He did this by putting a tester on it at the pedal and having another tech yank on the harness from outside.

Long story short, they were able to find and fix my gremlin for about 2 1/2 hours of dealership labor. I felt bad that I couldn't come up with the answer on my own but it was worth the $200 to be done at that point.

I feel certain now that the Napa pedals were not defective however I have a new Ford pedal in the truck and have kept the one that came out of it as my backup spare.

I hope someone else can benefit from my ordeal and I really appreciate y'all's help.

Thanks, Trey