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  #1  
Old 06-06-2019, 02:19 PM
blackseven blackseven is offline
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Default Dead throttle, no codes.

I've intermittantly been having an issue where I have to hold the accelerator to the floor for 3-5 seconds before the truck responds to the thottle input. It only happens when my truck is hooked up to my trailer via 7pin, and it started happening after driving through about 5-6 inches of water during a storm in New Mexico. I've had zero other issues with the truck, once it gets going it runs like an absolute beast. Doesn't do it when the trailer isn't connected, and it doesn't happen all the time. Sometimes the delay is just a fraction of a second and sometimes it's a solid 5 seconds.

I've noticed when I come to a stop if I pedal the truck and hold the brake I can keep it from returning to idle and going into that weird no-response state.

Forscan shows no stored codes, and the throttle input as expected, it shows an increase in commanded and actual fuel rail pressure, but no increase in RPM. Sometimes the idle dips 50-100 rpm when the issue is occurring. It can free rev just fine in Neutral and park. The problem only happens in gear.

Truck is on a diet with tunes and has been for about 40k miles.

My next step is to reset the trans learning via forscan and check for water/corrosion/wire issues around the TCM and ground wires under the truck and in the wheel well.

Any thing else I should check? It seems like the trailer wiring grounds might be part of the problem. It was hooked up when I went through the high water.
  #2  
Old 06-08-2019, 08:51 AM
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lincolnlocker lincolnlocker is offline
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A grounding issue may have back fed something and fried it. Can you monitor throttle percentage input through forscan and see if it is responding at all or see when it spikes?

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  #3  
Old 06-08-2019, 06:38 PM
blackseven blackseven is offline
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Throttle percentage is reading zero. The maf is reading 100% load at idle when the truck is in gear, and its idling like garbage. I think the turbo might be taking a dump. But it's not making any noise yet.
  #4  
Old 06-09-2019, 01:52 PM
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Quote:
Originally Posted by blackseven View Post
Throttle percentage is reading zero. The maf is reading 100% load at idle when the truck is in gear, and its idling like garbage. I think the turbo might be taking a dump. But it's not making any noise yet.


So when you press the throttle it doesn’t read 0-100% on the scanner? Sounds like a TPS to me.


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  #5  
Old 06-09-2019, 05:05 PM
blackseven blackseven is offline
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Where is the tps on a 6.7?
  #6  
Old 06-10-2019, 06:27 AM
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Quote:
Originally Posted by blackseven View Post
Where is the tps on a 6.7?
Its the black box thingy on top of the pedal. Has a 2 wire connector coming out of the top.


Thats odd about the maf sensor at the same time. Almost like it is in default. Wonder if they did short out.

live life full throttle
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00,f350,4x4,cc,drw. Sold... good bye ole girl. I will miss you
15,f350,4x4,cclb, not stock
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  #7  
Old 06-10-2019, 07:16 AM
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Quote:
Originally Posted by lincolnlocker View Post
Its the black box thingy on top of the pedal. Has a 2 wire connector coming out of the top.


Thats odd about the maf sensor at the same time. Almost like it is in default. Wonder if they did short out.

live life full throttle


I wonder if the MAF is reading that because of the TPS though.

Does your scanner read hertz?


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  #8  
Old 06-10-2019, 07:21 AM
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Quote:
Originally Posted by Motostroker View Post
I wonder if the MAF is reading that because of the TPS though.

Does your scanner read hertz?


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I haven't looked or used it to diagnose anything like that. I change features with forscan, pull codes and use it as a monitor with a cheap tablet.

live life full throttle
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00,f350,4x4,cc,drw. Sold... good bye ole girl. I will miss you
15,f350,4x4,cclb, not stock
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  #9  
Old 06-10-2019, 03:34 PM
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Good news, I got an updated tune for the elevation. I'm not sure what he did, I just described the issue and the fact that if I go from 8800 to 4000 feet the problem was no where near as bad. The new tune completely fixed the problem.
  #10  
Old 06-10-2019, 04:45 PM
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Quote:
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Good news, I got an updated tune for the elevation. I'm not sure what he did, I just described the issue and the fact that if I go from 8800 to 4000 feet the problem was no where near as bad. The new tune completely fixed the problem.


Sounds like MAF scaling.


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