Troubleshooting dead end on dead pedal. Apologize for a long thread in advance

[1ngenro]

Hello all, I am new to this site and wanted to kick something around maybe get some feedback and troubleshooting help.

When i would turn on the truck, i would usually let it idle for awhile. I would put it in “D”, push on the gas, the truck would start to travel, than it will suddenly get the case of the "dead pedal" and then kick into gear. This started in a sporadic fashion. It then led to a daily ritual to get to work having to rev-up the engine in order for the truck to move. I have briefly explained below how I got to this point.

The beginning of this story is as follows:

I initially replaced the fuel lift pump when I first got the signs of white smoke coming out of the tailpipe and the engine stalling out with my check gages notification on the dash (5 years ago). I replaced the lift pump, the problem went away for about 2 years (no codes). The white smoke eventually came back, so I replaced the lift pump again and the white smoke went away again and lasted for 2 years (no codes). I replaced it with a third and changed out the filter (1 year)(no codes). I finally got the case of the dead pedal and replaced my VP44 at 189,000 miles (figured it was time since I did not get any codes and read bluechip diesels overview). I installed the VP44 and finally got a companion code P1693 when i tried to start it up. I finally pulled the codes from the PCM and got the P0122 low voltage APPS code. I replaced the original APPS with a TIMBO and I now I have intermittent dead pedal. I also have the loss of power like if I am towing something at take-off. I punch the gas violently than the truck finally starts to sputter and then go away and begin to function properly and picks up speed. On the interstate, the truck runs fine once I start traveling at a constant speed. This behavior only occurs initially at rest or when I slow down and then punch the gas.

I have questions that may or may not relate to my problems, which are as follows:

[*]When i replaced the VP44, did i somehow take it off its timing?

[*]Does this mean my ECM is the culprit and not the VP44?

[*]Can i rule out the transmission due to not pulling any load?

[*]Did i purchase a bad OEM VP44?

When I installed the TIMBO Apps, I smelled burnt plastic that eventually went away. I am attributing it to that new plastic smell. I also noticed that when I hooked up the voltmeter, I got a reading of .510. I followed the instructions and when I turned back to ½ a turn as instructed, I ended up at .510 again, is this right? (the original apps has .521 VDC) Do I need to set it at .521, .498, or leave it at .510?

I have recently replaced one of the batteries (drivers side), but still have the original battery on passenger side. Can it be related to the problem that I have? Do I need to replace that battery as well?

Any and all comments are welcome. I thank you for your feedback in advance.

[Mopar1973Man]

On the Timbo APPS there is technically no voltage adjustment. Just keep twisting the stop screw till the voltage rises the back off till its at the orignal voltage and add a 1/2 turn. Basically at the APPS signal rises the ECM is triggered to THROTTLING mode. Then when the throttle is released it should be at IDLE MODE. So be sure your voltage is at its lowest point plus a half turn...

As for the dead pedal there is only 2 causes...

1. Bad APPS sensor which ALWAYS throws a code P0121, P0122, P0123...

2. Bad VP44 which doesn't have to toss a code but could... P0215, P0216, P0251, P0252, P0253, P1688, P01689... But like I said not all the time will it throw a code...

Now you mention you replaced the lift pump a few times... But didn't mention the fact of what your fuel pressure is. This is critical to know! Remember the only thing that lubes and cools the VP44 is the fuel. So if you short fuel pressure the VP44 can and will take on damage either mechanical (white smoke - failing advancement cam) or electronic (dead pedal). When the fuel pressure start falling below 14 PSI the overflow valve starts to close and reduce the cooling and lubing of the VP44... So since there is no extra fuel leaving the pump because the overflow valve is closed then that means the only fuel to cool and lube the pump is what going to the injections which typical doesn't flow enough.

Lack of fuel pressure is like a lack of oil pressure on the engine... Do you expect the engine to survive very long at 10 PSI running 2,500 rpms? Well the VP44 has to live on a very small margin for fuel pressure...

Keep it in the green at all time and the VP44 will live a very long and happy live normally...

[ISX]

As for the battery thing you mentioned, you should change them out in pairs. Batteries equalize so if one is bad, then the other will be drained as well. Try and get identical batteries too. Don't worry about it being a long thread, the longer it is the more details we got and the less time we have to spend getting more info out of you

[Terry C]

A way to check the APPS is to use an analog (needle type) ohm meter. The needle SHOULD sweep nice and steady when you open the throttle. You will be able to see any dips or jumps. Do you by chance have any sort of programming box on your truck? I saw one that would get a dead pedal after about 30 seconds of run time and would not even shut the truck off with the key. Turned out to be the box was screwy.

[cajflynn]

I had the dead pedal for the longest time. I replaced everything and no help. I bought a $20 bd ground isolator and now I have no problems. I highly suggest you try this.

[1ngenro]

Sorry about the delay! mopar1973man, thanks for the response. I did not check the pressure of the lift pump when i initially replaced them, my bad. I did check the lift pump pressure this weekend and it was above 10 psi. Ini regards to the TIMBO Apps, i started from scratch and re-installed it as instructed. The Initial voltage was fluctuating between .604-.605 volts and never stopped. I turned the idle stop screw until it changed to .606. I proceeded to 1/2 a turn and got back to .605, than added an additional 1/2 turn and ended up at .604-.605( fluctuating). Please explain why there is fluctuation or do i need to turn till it get a solid .604? ISX, thanks for your response. I had the battery on the passenger side checked and i am still at 12V. Terry C, thanks for your response. I did check to see if my voltage would fluctuate using a digital voltmeter and did not observe any numbers jumping around. I did notice that i started at .604/.605V (fluctuating) and ended up at 3.09 volts. Is this correct? I read another thread that said they started at .5V and ended up at 5V. Is this why i am getting a P0122? cajflynn, thanks for the response. I will look into this further by reading other threads pertaining to the ground isolator. I thank you all for you patience in advance.

[Mopar1973Man]

Sorry about the delay! mopar1973man, thanks for the response. I did not check the pressure of the lift pump when i initially replaced them, my bad. I did check the lift pump pressure this weekend and it was above 10 psi. Ini regards to the TIMBO Apps, i started from scratch and re-installed it as instructed. The Initial voltage was fluctuating between .604-.605 volts and never stopped. I turned the idle stop screw until it changed to .606. I proceeded to 1/2 a turn and got back to .605, than added an additional 1/2 turn and ended up at .604-.605( fluctuating). Please explain why there is fluctuation or do i need to turn till it get a solid .604?

I wouldn't worry about the slight voltage wander... When you start worrying is when you have +/- 0.1 volt changes... But a +/- 0.001 nothing to worry about...

[white01]

I had the dead pedal for the longest time. I replaced everything and no help. I bought a $20 bd ground isolator and now I have no problems. I highly suggest you try this.

CAJ...you are saying that the bd noise filter works..i have heared yes and no?

[1ngenro]

i still get dead pedal. I am back to square one. One of the things i am noticing now is that when i initially start the truck and i am idling in "D" at a stop light, it seems like it gets out of gear and then gets back into gear as the truck is switching back and forth, do you know what i am talking about? it is when the truck is initially turned on and during warm up, there is this loud click that changes the rpm of the motor to really high, then clicks back really loud to low rpm. can someone please explain?

[dripley]

i still get dead pedal. I am back to square one. One of the things i am noticing now is that when i initially start the truck and i am idling in "D" at a stop light, it seems like it gets out of gear and then gets back into gear as the truck is switching back and forth, do you know what i am talking about? it is when the truck is initially turned on and during warm up, there is this loud click that changes the rpm of the motor to really high, then clicks back really loud to low rpm. can someone please explain?

that sounds like your grid heaters in your intake. they will cycle on and off when you first start your truck. mine has always done this especially in cold weather, though i experience no rpm change only the sound of the engine going form load to no load due to the amp draw on the alternater. they draw alot of electrical power. ISX is right about your batteries they should be changed in matched pairs. when you checked the voltage, were both batteries still connected to the truck? by the welcome to the site. you will get alot of good info here.

[Terry C]

Terry C, thanks for your response. I did check to see if my voltage would fluctuate using a digital voltmeter and did not observe any numbers jumping around. I did notice that i started at .604/.605V (fluctuating) and ended up at 3.09 volts. Is this correct? I read another thread that said they started at .5V and ended up at 5V. Is this why i am getting a P0122?

Sounds to me like you didn't use an ANALOG meter. The reason I said analog was because of the needle on the display. If there were any 'flaky' spots in the APPS you would see them with the needle a lot easier than with a DMM. From what you say about what you end up with it does sound like the 3.09 is giving you the P0122. Do you just by chance have any fueling/timing box on your truck? If you do unhook it completely and put the truck back to stock and let us know what happens.

[1ngenro]

dripley, thanks for your response and greetings. i stand corrected. there is no rpm change. your description is accurate. I am going to assume that since these heaters have a very large amp draw, than it is possible that my apps sensor(TIMBO or stock) is seeing low voltage at the time, therefore resulting in the gear-out of gear feeling. Is this correct? Are these heaters on all the time or are they only on at initial start-up? At the time i took the measurement using a DMM, the batteries were not connected. Should i re-connect and take a reading? TerryC, thanks for your response. No, i did not use an ANALOG meter. I used a DMM. No, I do not have any fueling/ timing box on my truck. It is a stock assembly, with exceptions to lift pump, VP44, and TIMBO Apps. Thanks again!

[Mopar1973Man]

Grid heater draw 195 Amps the alternator produces 120 Amps... So yes the voltage will fall some while cold starting... But typically doesn't drop below 12 volts...

As for the grid heater they typically come on for the length of the Then once the light goes out and you start the truck then the grid heater cycle on and off as the engine is idling to mantain good manifold temp. Now once your rolling 20-25 MPH the grid heater are cancelled completely.

If you disconnecting your batteries make sure to do the APPS Reset and re-calibrate it for the ECM.

[dripley]

dripley, thanks for your response and greetings. i stand corrected. there is no rpm change. your description is accurate. I am going to assume that since these heaters have a very large amp draw, than it is possible that my apps sensor(TIMBO or stock) is seeing low voltage at the time, therefore resulting in the gear-out of gear feeling. Is this correct? Are these heaters on all the time or are they only on at initial start-up? At the time i took the measurement using a DMM, the batteries were not connected. Should i re-connect and take a reading?

TerryC, thanks for your response. No, i did not use an ANALOG meter. I used a DMM. No, I do not have any fueling/ timing box on my truck. It is a stock assembly, with exceptions to lift pump, VP44, and TIMBO Apps.

Thanks again!

you are welcome sir.

my truck is a manual and i get gear in and out feeling, just something that loads the engine. might feel that way in an auto, dont know. it should not affect your apps though since it operates on 5 volts(someone correct me if i am wrong abotu that). as far as your batteries if you test them while they are connected you will only be as good as your worst battery. testing them disconnecte is the right way, and if you did have them both disconnected you do need to resest your apps. just connect the batteries, turn the switch the on position, truck not running, slowly depress and release the throttle and turn it off. it is reset:hyper:.

sorry it took so long to get back with you.

--- Update to the previous post...

Grid heater draw 195 Amps the alternator produces 120 Amps... So yes the voltage will fall some while cold starting... But typically doesn't drop below 12 volts...

As for the grid heater they typically come on for the length of the Then once the light goes out and you start the truck then the grid heater cycle on and off as the engine is idling to mantain good manifold temp. Now once your rolling 20-25 MPH the grid heater are cancelled completely.

If you disconnecting your batteries make sure to do the APPS Reset and re-calibrate it for the ECM.

mike, for the first 8 years i had my truck the heaters would pull my voltage down as low as 9 volts and dimthe heck out of the lights:stuned:. i just thought that was normal after it was explained to me what it was. did that until my ecm took a crap. with the rebuilt one it might pull it down to 11 and they cycle quickly and turn off quickly. totally different behavior now.

does that first description sound like yours 1?

[cajflynn]

CAJ...you are saying that the bd noise filter works..i have heared yes and no?

It works great for me and my brother. Before I got it I had to reset my apps every 1000 miles. I haven't had any problems now since I installed it.

--- Update to the previous post...

Sorry about the delay!

mopar1973man, thanks for the response. I did not check the pressure of the lift pump when i initially replaced them, my bad. I did check the lift pump pressure this weekend and it was above 10 psi. Ini regards to the TIMBO Apps, i started from scratch and re-installed it as instructed. The Initial voltage was fluctuating between .604-.605 volts and never stopped. I turned the idle stop screw until it changed to .606. I proceeded to 1/2 a turn and got back to .605, than added an additional 1/2 turn and ended up at .604-.605( fluctuating). Please explain why there is fluctuation or do i need to turn till it get a solid .604?

ISX, thanks for your response. I had the battery on the passenger side checked and i am still at 12V.

Terry C, thanks for your response. I did check to see if my voltage would fluctuate using a digital voltmeter and did not observe any numbers jumping around. I did notice that i started at .604/.605V (fluctuating) and ended up at 3.09 volts. Is this correct? I read another thread that said they started at .5V and ended up at 5V. Is this why i am getting a P0122?

cajflynn, thanks for the response. I will look into this further by reading other threads pertaining to the ground isolator.

I thank you all for you patience in advance.

I called Tim and he walked me through the setup as I did it. I told him the values and he told me which way to adjust. Have you callled him about it? The way he had me do it was not the same as the instuctions said.

[Mopar1973Man]

mike, for the first 8 years i had my truck the heaters would pull my voltage down as low as 9 volts and dimthe heck out of the lights:stuned:. i just thought that was normal after it was explained to me what it was. did that until my ecm took a crap. with the rebuilt one it might pull it down to 11 and they cycle quickly and turn off quickly. totally different behavior now. does that first description sound like yours 1?

Hmmm... even with my old batteries (factory 9 years old) I rarely see below 11.0 volts with just turning on the key... Even with the engine running I never get below 12.0... Yeah mine dim but not that bad...

[1ngenro]

cajflynn, i called him but kept getting his voicemail. I will try again this weekend to troubleshoot my problem further. okay, so i reset my apps. i checked the old battery and it was at 12V disconnected and 13 V connected while the truck was running. I think i can rule out the battery. I also cleared the codes yesterday due to obtaining the P0122 code. This morning i turned the truck on and it was having a hard time trying to start up as if it was being starved of fuel. The truck eventually strated running fine. I let it sit idle for about 10 minutes. On my way to work, i was still experiencing dead pedal and now the truck felt like it wanted to turn-off on me like if it was running out of fuel (i still have about 1/4 tank of fuel left). I was about a couple of blocks from my work when the truck finally died:ahhh:. I tried turning it on, but no luck. Any ideas?

[dripley]

lift pump maybe. earlier you said you had replaced a few. how old is the one you have now? is it the oem style? do you have any fuel pressure to the vp44?

[1ngenro]

Dripley, the liftt pump is no more than two years old I had some help in getting it started with carb cleaner. The guy told me it happens to him alot when he doesn't let the truck warm up. Any ideas?

[dripley]

my original lasted 145k. the dealer fixed it with aan intank unit, oh joy. i think its worse than the stock one. had to install a booster pump just to get enogh pressure to run the vp. lot of folks here have seen them go alot quicker, less than a year. check your fuel pressure to the pump. there is a schrader valve on theinlet to the vp that you can attach a test gauge to. at least you can eliminate that as a problem. when you say you got it started with carb cleaner, did you use it like starter fluid? if so be aware that those intake heaters we talked about can ignite the fluid in your air intake system and cause all kind of problems:ahhh: