Engine/Transmission (1998.5 - 2002) Intermittant Hot Fast Idle Problem

[CyberRanger]

Howdy y'all!



I searched the forum for an hour & cannot find anyone else who has had this problem...



We have a 2002 2500 4x4 QC w/ the HO Cummins, 6 spd, 3. 55 gears. It has approx. 11K miles on it & so far we have done only about 200 miles of towing, but it does get about 725 mi/wk of mtn driving. The truck is completely stock except for a Tekonsha Prodigy brake controller. We average about 17. 5 mpg for virtually every tank. My wife drives the truck to & from work w/ about a 2200 ft difference in altitude between our home & her work.



We drove from Colorado to KC Saturday along I-80 & then down I-29, running about 81 mph most of the way across Nebraska, w/ about 1000 lbs in the bed. About the 3rd stop (a new puppy was along requiring more frequent stops) the engine refused to idle down below 1400. Engine temp & oil pressure were normal. In fact, other than the fast idle everything was normal. Our mileage had been near normal so far & has been since this problem surfaced. The problem went away as soon as the truck was shut off & restarted. The same problem reaccurred 2 more times--the second time it didn't want to idle below 1250 & the last time it didn't want to idle below 1150. The only commonality was that the truck had been driven for more than an hour at a time at or above 55 mph. The first time it occured we'd driven for about 90 min at 81, the second time about 80 minutes at 81 & the last time at 55 or more for about 105 minutes. We stopped twice in between the 2nd & last time, w/o the problem occuring. Each time the problem would disappear as soon as the truck was shut off & restarted after several minutes. Ambiant air temp was roughly between 32ºF & 40ºF & it was dry.



I need to call Sunflower Dodge or Cummins here in KC to see if they can identify this problem, but I thought I'd see if anyone on on the forum has had a similar problem & solved it, so I can go to Dodge or Cummins a bit more informed. We have had zero problems w/ the truck & love it to no end.



It doesn't affect the driveability of the truck other than it's a bit annoying when parking or driving slow.

 

[Phil Stuart]

Fast Idle problem

Welcome aboard!



I'm gonna try at this since no one else has replied.



You say it will not return to normal idle after running at highway speed for a given amount of time.

I'm thinking maybe the APPS on the bellcrank assy. is out of range or a bad connection?Then again I would think this would have thrown you a code or something. Did it set any codes?Since it runs fine other than idle. I'm sorry, this is all I could come up with right now. myself.



Others may have better ideas.



Phil

 

[CyberRanger]

Re: Fast Idle problem

Originally posted by Phil Stuart

You say it will not return to normal idle after running at highway speed for a given amount of time.

I'm thinking maybe the APPS on the bellcrank assy. is out of range or a bad connection?Then again I would think this would have thrown you a code or something. Did it set any codes?Since it runs fine other than idle. I'm sorry, this is all I could come up with right now. myself.

Thanks Phil! Been reading for sometime & a member for a couple of years. We just bought this 2002 the end of July, but I've been investigating putting a 5. 9 in my '71 Chevy for a several years (money is the big obstacle right now). Both my father-in-law & my father have had 5. 9's.



I was thinkin' maybe somethin' like this myself, but the problem didn't occur 2 other times between the 2nd & 3rd instances. Since then, it has run fine. We haven't driven it for as long or at extended highway speeds since the last occurance.



This reeks of some kind of solenoid sticking, since it didn't stay at the same high idle each time. I figure if it was a sensor out of range, it would idle high at the same RPM each time. I used to be a diesel/4x4 mechanic, but that was long before computer control diesels. I haven't tried to pull a code yet & may, if I can't get Dodge or Cummins to look at it right away.



I was hoping someone else had run into this specific problem, but b/c I couldn't find it by searching the 24V forum, I may not be able to.

 

[1tuffram]

This probably won't help you, but I recall reading about this same problem recently. Guess you are not alone.

 

[CyberRanger]

Originally posted by 1tuffram

This probably won't help you, but I recall reading about this same problem recently. Guess you are not alone.

Do you remember where you read it? (I am trying to recall anything I've read lately in the last couple of issues?????)



Thanks. That's a starting point.

 

[1tuffram]

Originally posted by CyberRanger

Do you remember where you read it? (I am trying to recall anything I've read lately in the last couple of issues?????)



Thanks. That's a starting point.

I think it was either here (TDR) or over at Dodge-Diesel.org site. I'll do a little browsing to see what I find. I could be thinking about a thread I read on a 2003 truck with a bad TPS (Cummins rep told owner they have been having problems with moisture getting inside the sensor) giving idle problems.

 

[Phil Stuart]

maybe we're getting somewhere

Hey guys,

I'd like to know also what it is when you find out.



That's the only thing I don't like about electronic controlled engines



Got me thinking here.



Phil

 

[draymorris]

High Idle problem

I was looking at your post because my brother drives a 92 that has been acting up - but yours is different.



There is a procedure for resetting the APPS on here somewhere, if you wanted to try it. Do you know how to find the error codes? If you do, you might want to see if it has an error and if it does post the error as a topic on this site. -- I you don't, write back and I will find both of these procedures for you.



By the way, my 02 has normally only gets 16. 3 MPG. How does yours get over 20 MPG?



It seems that the more I read and the more I talk to Cummins owners - the more it seems that every engine gets different milage from the factory.



Being a mechanic - do you have any thoughts on my brother's problem? It "lopes" when idling , sometimes. No pattern to his problem either.

 

[Phil Stuart]

recalibrating the APPS

draymorris,



If'n I'm not mistaken here I thought I saw something in the 2002 FSM on resetting the APPS calibration. It requires the ignition to be turned on but not to start the engine,then press the accelerator pedal to the floor and release slowly all the way. This should do it.

Apparently it tells the FPCM and or ECM what position the pedal is at via the APPS. Hope this helps.



Phil

 

[CyberRanger]

Well, I talked to Dodge (2 dealerships) today & Cummins. None had a specific answer, but none thought it was a major problem. Cummins & 1 dealership seemed to think it might have to do w/ a sticky solenoid that is tied into the cruise control, since the cruise had been on prior to all 3 occurances.



They also believed it had nothing to do w/ the APPS b/c it didn't activate the "Check Engine". B/c the "Check Engine" light didn't come on there would also be no trouble code for me to retrieve.



It hasn't given us any more trouble since, so we'll just have to wait & see. B/c of the holidays, I couldn't get it in to a dealership until Thursday, so we may have to wait until we get home to get it repaired.



A lope at idle is usually indicative of unequal injection into one or two cylinders. A quick way to check this would be to take a temperature reading at the exhaust port at the exhaust manifold w/ an infrared gun. A major temperature variation in one cylinder may indicate a malfunctioning injector. This used to more prevalent w/ the old Cummins PT fuel system, but can still indicate a sticky or dribbling injector.



Fuel mileage on our 2002 seems to vary greatly depending on the driving conditions. We do a lot of driving on steep grades & almost no interstate or freeway driving. We are also finding that driving 5 or 10 mph faster vastly decreases mileage.

 

[Shelby Griggs]

I may have a related problem

I have of late been finding a similar thing, but usually only 50-100 RPM's higher. Not really enough to notice EXCEPT my Jacobs E-Brake won't activate. After shutting down and restarting everything works fine. I have to drive 1-2 hours first, which is usually done using the cruise control. On the newer trucks 2001. 5 and up, the cruise is supposedly all done by computer control, should be no solenoids or servos, etc. involved. I suspect this may be an ECM problem.



Mine goes to the dealer for this, a new lift pump, and the bogus tamper alert from the alarm the day after Christmas.



Stay Tuned.



Shelby

 

[CyberRanger]

Re: I may have a related problem

Originally posted by Shelby Griggs

I have of late been finding a similar thing, but usually only 50-100 RPM's higher. Not really enough to notice EXCEPT my Jacobs E-Brake won't activate. After shutting down and restarting everything works fine. I have to drive 1-2 hours first, which is usually done using the cruise control. On the newer trucks 2001. 5 and up, the cruise is supposedly all done by computer control, should be no solenoids or servos, etc. involved. I suspect this may be an ECM problem.



Mine goes to the dealer for this, a new lift pump, and the bogus tamper alert from the alarm the day after Christmas.

Even if its done by computer control, something mechanical or electromechanical must actuate the throttle whether it be a computer controlled solenoid or stepper motor. Even the hard drives in our computers have to use a stepper motor to actuate the read/write heads & a drive motor must spin the platters. (These & the logic boards on the drive are usually what fails). Something physically must do the work, even if its inside the fuel pump.



I'll be very interested to see what they find on yours.

 

[Shelby Griggs]

I don't think there is a mechanical connection. What I think happens (just a guess) is that the ECM sends out the request for more or less fuel to maintain road speed, and then the VP44 acts accordingly. There is no movement of the accelerator pedal in the new trucks as the cruise maintains speed.



Shelby

 

[kaffine krazed]

There is no mechanical connection between the throttle cable and the fuel pump the fuel pump adjust timing and amount of fuel using solenoids. I don't know why Dodge insistes on using a throttle cable they should just mount the TPS on the pedal. Cruise control on the 6sp I know is not mechanical it is all electronic. Just because the check engine light isn't on doesn't mean there are no codes not all codes will turn the light on. You can cylcle the ignition key from off to on 3 times ending up in the on postion and the codes will be displayed in the odometer window.

 

[CyberRanger]

OK, I ran that sequence & pulled a P 0500 trouble code. Now I just need to find out what that means. That was the only code I got.



[10 minutes later... ]



OK, P 0500 means the truck isn't moving. Duh! I should've known. Guess that's the trouble code you get when the engine off & your sittin' in the driveway.



So, essentially I have gotten no trouble codes.

 

[draymorris]

P0500

Every one check the codes sitting still. It would be very dangerous otherwise. I know my truck does not default to that code. Try listing that code on this site as a topic. maybe you will get some new hits. Thanks for input about my brothers truck - it seems to have gone away - bad fuel?

 

[CyberRanger]

Actually I did a search on the forum & that's how I found out what it meant.

 

[Shelby Griggs]

Had my truck to the dealer for the intermittent no e-brake malfunction which I believe is related to a high idle condition. No clue, but of course they couldn't duplicate the problem either. Hopefully this will fail during business hours when I am close to the dealer so I can show them. Otherwise I don't anticipate them offering a solution, and actually I don't blame them if they can't actually see what is happening.



Shelby

 

[SandDemon]

Just got the same problem last night. Twice after 1-2 hours towing on cruise the idle was well over 1000rpm when I stopped for fuel. No Codes were thrown. After towing with the cruise off, no idle problem.



First time it happend I tried unplugging my EZ. No change. Cycling ignition fixes it.



Wierd. TPS comes to mind.

 

[CyberRanger]

Well, we drove all the way back (700 miles) w/o any troubles. The problem seems to have cured itself. I ran the cruise most of the way back, as well. The weather conditions were somewhat similar.



This may be a new truck bug that just disappears over time. Oh, well.