Intermittant "dead zone" in pedal - NO CODES

[mgray]

This morning was the second time this happened. Started up normal other than my dying batteries giving a hard start and some blue smoke. For the next 5 or so minutes the pedal sometimes needs to be pushed further than normal to get initial response. It's intermittent when it's doing this, and once I get throttle response everything seems normal, just the pedal is pressed further than normal. I haven't noticed this any other time other then when cold.

It's been at least a few weeks since I fueled her up, and I only added my summer Power Service Grey Bottle. Temps are now around 10c/50f, wondering if it could be some gelling?

No lights on dash, and I have no code reader. I would assume the APP(pedal sensor) would throw a code and light the "Service Throttle" light if something was wrong with the sensor wouldn't it?

Any ides? Thanks guys

 

[great white]

I very infrequently get the same thing with my 98.

No codes or other indications.

I just lift and reapply the throttle (takes less than a sec) and it responds as normal.

Why does it do it?

Dunno, all I can do is guess:

Loss of redundancy in pedal assy
bit of "glitchy" code in the PCM
App doesn't respond with the correct voltage due to humidty, corrosion, etc

Or

"Anything electrical or with a wire attached to it is inheriently faulty by nature and subject to failure"

I used to worry about it, but don't anymore as long as a "reset" (lift and reapply) has it responding normal.


Trucks by Windows......

:rolleyes5:

In your case, low voltage at idle could be messing with the electronics on your truck.

Most likely not, but it's a possability. Especially if your Alt is weak too.

Plus, dropping temps and rising humidity here in BC this time of year isn't going to help any electrical "weaknessess" either...

 

[ak diesel driver]

http://www.thetruckstop.us/forum/showthread.php?11489-Hard-Cold-Start&highlight=hard+cold+start Check out this thread I had a dead pedal when cold too.

 

[bison]

I got that problem too with my 98,dead pedal first start cold.Rough below RPM (no rattle)running and lots of smoke.
Shut down and restart clears it up for me.
I'm pretty 99% sure its the stepper motor,i got plenty of these, i just need the motivation to get at it and replace it.

 

[Paveltolz]

I had the intermittent dead pedal about a week after replacing the IP. No air that I was aware of and a new D-Tech didn't solve it either. Sure was annoying. Spoke with a wiser head about it, thinking it was the APP too, and at his suggestion I ran a triple dose of 2 stroke through the next tank and double doses for the next couple of tanks there after (I'd been using the Stanadyne stuff only). Good thing it cleared up because it was suggested the IP was more than likely at fault.

The day after I replaced the Lift Pump last month it happened a couple of times. I'm certain this WAS an air bubble as it cleared up same day w/o adding additional 2 stroke.

As suggested, I would definately work over any electrical issues though (grounds, batteries etc) and you may want to get a Tech 2 Scan readout on how healthy the IP is.

 

[btfarm]

It's been at least a few weeks since I fueled her up, and I only added my summer Power Service Grey Bottle. Temps are now around 10c/50f, wondering if it could be some gelling?

I doubt that gelling is happening at those temps.

 

[HighSierra86]

I very infrequently get the same thing with my 98.

No codes or other indications.

I just lift and reapply the throttle (takes less than a sec) and it responds as normal.

Why does it do it?

Dunno, all I can do is guess:

Loss of redundancy in pedal assy
bit of "glitchy" code in the PCM
App doesn't respond with the correct voltage due to humidty, corrosion, etc

Or

"Anything electrical or with a wire attached to it is inheriently faulty by nature and subject to failure"

I used to worry about it, but don't anymore as long as a "reset" (lift and reapply) has it responding normal.

This describes exactaly what my 96 does. Ive never chased the problem due to the fact that it is only very rarely that it happens. Mine does it with a cold or warm engine.

I personaly dont think it has anything to do with the IP, pmd, fuel system etc. I think it is somewhat of a "brain fart" in the electrical system either from the fly-by-wire throttle pedal or the pcm.

Low voltage readings from weak/near dead batteries can cause some wierd electrical problems or engine codes. I would suggest some new batteries as you are going to need them soon anyways.

 

[mgray]

Well I'm somewhat happy to hear others have the same thing, and that it's not really an issue. I'm definitely one of those guys who likes to find out why everything is doing what it does, even if it's not really a problem, I'd still like to try and fix it.

It's funny how so many "conditions" always seem to be blamed on the IP. I think I have 3 things going on right now, that people blame on the IP. But I'm still rolling, so my IP must be dying a slow death!

But thanks for the ideas guys, I feel a little better about it now.

 

[THEFERMANATOR]

I believe this is an APPS problem more so than anything else. I ran my old 6.5 pedal with the DURAMAX and got the same thing where some times you have to give it more pedal to go or a blip then back to idle. Installed a new pedal assembly, and the same exact problem. The DURAMAX didn't do this with the 01+ pedal assembly, but it was too much of a hassle to swap one in so I stuck with the new 6.5 pedal.

 

[ak diesel driver]

I put another 15 to 20k on mine after I first noticed the problem.

 

[great white]

I believe this is an APPS problem more so than anything else. I ran my old 6.5 pedal with the DURAMAX and got the same thing where some times you have to give it more pedal to go or a blip then back to idle. Installed a new pedal assembly, and the same exact problem. The DURAMAX didn't do this with the 01+ pedal assembly, but it was too much of a hassle to swap one in so I stuck with the new 6.5 pedal.

Hey Ferm, question for you since you seem to have travelled this road already:

If yo uused a 6.5 pedal, then I assume the duramax also fly by wire?

If so, do you know if the 'Max pedal would retro fit into the 6.5 trucks?

I haven't had one in my hands so I couldn't even guess.

If you're using a 6.5 pedal with a 'Max PCM, I can't see why it wouldn't work the other way around.

Especially if the "max pedal doesn't exhibit the "dead pedal" response the 6.5 APP seems to infrequently cause.

Just tossing around ideas here....

 

[THEFERMANATOR]

Hey Ferm, question for you since you seem to have travelled this road already:

If yo uused a 6.5 pedal, then I assume the duramax also fly by wire?

If so, do you know if the 'Max pedal would retro fit into the 6.5 trucks?

I haven't had one in my hands so I couldn't even guess.

If you're using a 6.5 pedal with a 'Max PCM, I can't see why it wouldn't work the other way around.

Especially if the "max pedal doesn't exhibit the "dead pedal" response the 6.5 APP seems to infrequently cause.

Just tossing around ideas here....

A DURAMAX pedal cannoy be retrofitted back to work on a drive by wire 6.5. The DURAMAX uses half the voltage swing in its pedal than a 6.5 does. With the 6.5 pedal I get 100% throttle at about 55-60% pedal movement. I believe the difference in voltage swing is part of the reason that the 6.5's get this dead pedal or dead zones. There is so much swing in the 3 outputs, that at points I believe they interfere with each other and cause interference to the ECM. I know all of the new DBW use the lower volatge swing pedals, so maybe there was a reason for the change.

 

[buddy]

It also may be APP programming in the PCM. The APP is not supposed to be active until you achieve a stable idle. If on first startup the PCM is hunting for idle it wont let the APP work. This could be from cold advance and cold idle lookup.

Is this happening right after statup, or after warmup? I typically never start it up and go without setting a minute, and I have not had this issue, and its never too cold here either.

 

[great white]

A DURAMAX pedal cannoy be retrofitted back to work on a drive by wire 6.5. The DURAMAX uses half the voltage swing in its pedal than a 6.5 does. With the 6.5 pedal I get 100% throttle at about 55-60% pedal movement. I believe the difference in voltage swing is part of the reason that the 6.5's get this dead pedal or dead zones. There is so much swing in the 3 outputs, that at points I believe they interfere with each other and cause interference to the ECM. I know all of the new DBW use the lower volatge swing pedals, so maybe there was a reason for the change.

Interesting.

I have access to those tables in tunercat II.

Hmmmm.......