Weird dead pedal issue

D-LUX

D-LUX

Just another white guy
Joined
Nov 12, 2010
Messages
234
I'm having the usual dead pedal issue at cruising speed in 4th or 5th gear during steady throttle situations. The kicker is I attributed it to a dying injection pump and replaced it, but the truck still does it.

I've done the key on/off trick to read the pcm and have hooked up my scanner but neither of them come back with anything. Ive also done the re-calibration for the apps sensor and it seems to help but only for a day or so. Now I have replaced the apps once before a few years ago with a timbo upgraded unit but idk if their any different than stock.

Anything yall would recommend to check other than the voltage at the apps? Is this a possible dying ecm? Any and all suggestions welcome


little history on the truck, one owner 2001 QCSB 4x4, 5 speed with the usual mods, intake, exhaust, clutch, airdog150, 150hp injectors, he351 & no tuner at the moment.
 
The timbo apps comes from a freightliner application if I recall correctly. Whatever they are from I have had zero issues out of the 5 or 6 I have installed for myself and others. Assuming you aren't getting any apps related codes? I had 1 truck a few years ago with dead pedal at cruising only. Ended up being the map sensor. Haven't read of anyone else replacing the map so I assume its very rare for it to contribute to dead pedal

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Do you think this could be ecm related to not throw any codes when it happens? I'll start at checking the voltage at the apps then possibly toss a map sensor in it. But I don't want to just keep throwing money at it. Between the pump/trans/steering box I've put a little over 3000 in it in the past two months


Sent from yo momma' house
 
jesnic7 said:
I would check the alternator a blown diode.
Click to expand...


How would I go about testing that?

Took a short video of the apps sensor voltage, everything seems fine. I plan on leaving my multimeter in the truck so when it starts acting up I can check it then before I reset the ecm/apps https://vimeo.com/139505689


Sent from yo momma' house
 
Apps is bad or it has slipped in the bracket. I had one do the same thing
 
I will say at the back of the alternator I'm only seeing 13.3 volts


Sent from yo momma' house
 
Ok I think the alternator may be part of this issue. With just the stereo/subs/amp it drags it down to 12.8 ish at idle and with the rpms around 1800-2000 only brings it up to 13.3ish

That sound normal? I've heard the pcm will determine voltage output based on outside temps and its roughly 90* today


Sent from yo momma' house
 
Similar issue on my 01, right around 40ish mph in 4th or 5th steady pedal pressure, it would "dead pedal". I could recover it easily be engaging the clutch and cycling the "go" peddle. I also note that it would go " dead" as soon as I tried to use cruise control. I installed a TIMBO APPS and haven't had any problems since.
 
inline said:
Similar issue on my 01, right around 40ish mph in 4th or 5th steady pedal pressure, it would "dead pedal". I could recover it easily be engaging the clutch and cycling the "go" peddle. I also note that it would go " dead" as soon as I tried to use cruise control. I installed a TIMBO APPS and haven't had any problems since.
Click to expand...


It has a timbo unit in it already just a few years old


Sent from yo momma' house
 
I had a similar issue and replaced the ecm 3 times, the map sensor, unplugged the edge box, new timbo apps, checked all grounds, new batteries. Only to find the alternator wasn't putting out the correct amps under load. Had it tested at auto zone. It took them 3 tests to determine it had a blown diode. I just replace the alternator now every year to make sure I don't have another problem. When I crank up the sound system and start blowing 200 amp fuses, I am sure the alternator starts to struggle and can't hang. At least, that's what I assuming has caused the issue on my truck.
 
Well there's a new alternator in it now. It was a warranty return deal at oreillys so I'm out nothing. Hopefully this solves the issue


Sent from yo momma' house
 
Man, I've got the same issue on a customers truck. It had an APPS code, but that didn't fix it, so I was sure it was the VP, especially since it would do it at any throttle %. VP didn't fix it either. I'm going to test AC voltage tmrw and maybe swap an ECM worst case.


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diesel_importer said:
Man, I've got the same issue on a customers truck. It had an APPS code, but that didn't fix it, so I was sure it was the VP, especially since it would do it at any throttle %. VP didn't fix it either. I'm going to test AC voltage tmrw and maybe swap an ECM worst case.


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Click to expand...


If you can let me know what the issue ends up being. I'll update this thread after a few days with this new alternator, hopefully with good news


Sent from yo momma' house
 
My alternator was reading .019 VAC. I believe that's ok. I slapped an ECM from an 01 automatic just to see and its running perfect other than being an auto ECM.


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If the APPS has a bad spot in it, and the spot returns a valid voltage to the ECM (such as it reads 7% when it should actually be at 75%) then you won't get any codes.

Replace the APPS. $.02
 
I always keep an APPS on hand, even if it's just a bad one I've swapped out. I work on too many of these trucks not to. The current truck threw me for a loop, It ran exactly like a failing VP. Started out really sporadic then got to where it would just fall on its face in any gear if you were trying to accelerate.


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Well its been a few days since the alternator replacement and it has seemed to solve my problem. Took the truck to the lease over the weekend and put a little over 400 miles on it with zero issues.
 
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